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                                                   PHILOSOPHY OF KNOWLEDGE



                                                                                      Paul Gerard Horrigan



                                                COPYRIGHT © 2005 By Paul Gerard Horrigan, Ph.D, All Rights Reserved.

                                      This HTML edition is provided free for noncommercial and educational use.


                                        (INTRODUCTION AND CHAPTERS 1-7)      





Other e-books by Dr. Paul Gerard Horrigan:

Introduction to Philosophy:  

A Short History of Philosophy:    

Philosophical Anthropology:

Introduction to Metaphysics:                           

Modern Philosophy: Descartes to Kant:

The Existence of God: 












1. Ancient Greek and Roman Philosophy of Knowledge


2. Medieval Philosophy of Knowledge


3. Modern Philosophy of Knowledge: Descartes to Kant


4. Nineteenth Century Philosophy of Knowledge: Absolute Idealism to Pragmatism


5. Contemporary Philosophy of Knowledge: Neo-Positivism to Husserl’s Phenomenology




6. The Nature of Knowledge


7. Sense Knowledge 


8. Intellectual Knowledge   FOR 8-12 AND BIBLIO:


9. Consciousness


10. Truth


11. The Ultimate Criterion of Truth


12. States of the Mind in Confrontation With Truth










Definition of Philosophy of Knowledge


A branch of the theoretical or speculative science[1] of philosophy,[2] philosophy of knowledge or gnoseology (from the Greek gnosis = knowledge, and logos = study) is defined as the science of knowledge studied from the philosophical point of view, or the science of knowledge in its ultimate causes and first principles. With this definition there is indicated both the material and formal objects[3] of this philosophical discipline, the material object (or the subject matter) being knowledge and the formal object (or the particular point of view or aspect in which the subject matter is viewed) being knowledge studied from the philosophical point of view or knowledge in its ultimate causes and first principles. 


Philosophy of Knowledge a Branch of Metaphysics


Since knowledge is a rapport between thought and reality, and that the end of this rapport is the truth, one can describe philosophy of knowledge as a metaphysical inquiry into truth. Why should we say specifically a metaphysical inquiry and not just a philosophical inquiry? It is because philosophy of knowledge’s sphere of inquiry is, in a certain sense, coextensive with metaphysics since, if the latter is concerned with the philosophical study of being, the former deals with our knowledge of being, that is, being inasmuch as it is knowable by the human mind.


Philosophy of Knowledge is Founded Upon General Metaphysics or Ontology


Though philosophy of knowledge is an essential part of metaphysics (metaphysics understood in the broad sense as the philosophical study of being), it is not the foundation of metaphysics proper or ontology (which is the philosophical study of being as being). Metaphysics is the foundation of knowledge since knowledge is not the foundation of being but rather being the foundation of knowledge.


Names Given to Our Subject Matter Throughout History


Various names have been given to our philosophical study of knowledge. Major logic, material logic, critical logic, and applied logic have all been used, but these terms detract from the fact that philosophy of knowledge is a branch of metaphysics, not logic (which is propaedeutic, that is, introductory, to philosophy). Therefore these terms should be avoided. Criteriology is etymologically derived from two Greek words, namely, kriterion (criteria, tests) and logos (science) and is traditionally defined as the science of the criteria or tests of truth.  But “criteriology” is too restrictive a term for our subject matter. It is really only a part of philosophy of knowledge or epistemology, the part dealing with the norms, tests or standards by which we distinguish truth from error (the ultimate crtierion of truth, as we will see later on in this book, is objective evidence). But there are many other problems to be dealt with as regards our subject matter, namely, what is knowledge in the first place, the origin and process of knowledge, what is truth, the various states of the mind in confrontation with truth, etc. Other terms used to designate our subject matter are critics and criticism, but rather than express a philosophical inquiry into the processes of human knowledge, such names instead invoke Cartesian and Kantian immanentism and doubt when confronted with common sense certainties and the first principles of human knowledge, and therefore these terms should be avoided. Epistemology etymologically means “study or science of knowledge” and is sufficiently broad enough as to include all the problems dealt with in our subject matter; however, there is a strong tendency nowadays to refer this term exclusively to philosophy of science or theory of science. The terms philosophy of knowledge or gnoseology are the best names to describe the philosophical study of knowledge since they are broad enough to embrace the whole sphere of questions that regard the possibility for the human mind to grasp being in the knowledge process. “Gnoseology” was made popular by the Italian philosophers Giuseppe Zamboni[4] and Sofia Vanni Rovighi.[5] However, since few persons these days are familiar with the term gnoseology, it was decided that the term philosophy of knowledge would be the title of this book.   


Presuppositions of Philosophy of Knowledge


The presuppositions of a science are certain truths or enunciations not proved by the science in question but are presupposed by it. They are by no means unwarranted assumptions but rather truths borrowed from other sciences whose province it is to investigate and establish them. The presuppositions of philosophy of knowledge include a certain knowledge of the principles of philosophical psychology, formal logic and general metaphysics.       


The Method of Philosophy of Knowledge


Induction and Deduction Both Utilized. The third operation of the mind,[6] reasoning can either be inductive or deductive. Induction is defined as the reasoning process whereby we conclude from individual cases to the existence and establishment of general principles or laws (in short, it goes from the particular to the general or universal),[7] while deduction is defined as the reasoning process whereby we conclude from a general principle or law to a particular instance falling under the general principle or law (in sum, it goes from the general or universal to the particular).[8] Philosophy of knowledge is both an inductive and deductive science. It is neither exclusively inductive nor exclusively deductive; rather, it utilizes both induction and deduction in varying proportions.

Cartesian Universal Doubt an Erroneous Method. The method[9] to be utilized in our study should not adopt the universal doubt posited by Descartes, which works from the data of pure consciousness, bracketing out the extra-mental, extra-subjective world, and, with a subsequent methodical mathematical deduction, seeks to justify and reconstruct it, as it makes something that is self-evident (reality) radically problematical. Cartesian universal doubt, in short, makes a non-problem a problem. One does not demonstrate something that is self-evident (e.g., the existence of the world); only something not immediately self-evident requires demonstration. It will also be explained in detail later on in this work why universal doubt is an impossibility. One who doubts everything is already certain of something, namely, that he doubts all things. 

What method, therefore, should be adopt for philosophy of knowledge? Rather than the Cartesian universal doubt one should undertake a systematic examination of human knowing, utilizing reflective judgment in the quest to determine human cognition’s true value, limitations and deficiencies, as well as to give an adequate response to the manifold objections. In short, not a real universal methodic doubt but rather an aporetic inquiry and examination of human knowledge and its relationship with the extra-mental world of beings. For the realist “the critical problem emerges and develops itself in the sphere of certain knowledge, and is posed not primarily to acquire a certainty, but rather to recognize in an explicit and systematic way the certainty that we have.”[10] “The problematic side of knowledge is produced in a context of the contemplation of truth, wherein the problems can appear precisely because the contemplation is not perfect, a fact that justifies gnoseological science.”[11] The method of philosophy of knowledge is not a “radical criticism” in its rationalist and transcendental idealist meanings, the a priori requisite for metaphysics, but an adequate reflective discernment concerning the issues involved in human cognition and its rapport with reality. Millan-Puelles explains that “the intellectual faculty is capable of understanding sense knowledge and, above all, (…) is capable of reflecting on its own acts and deficiencies of fact; in this sense we use terms like ‘to rethink,’ ‘to reconsider one’s opinions,’ ‘to revise our judgments,’ etc. However, all of this presupposes that even if – in fact, and in an accidental way – it is susceptible to error and deviation, our understanding is essentially apt to attain its proper end. If this were not the case, it would be meaningless to attempt to remedy its mistakes, because an understanding incapable of grasping the truth would never get out of error no matter how many times it went over the same ground. In the final analysis, all of the methods and precautions of science imply the fundamental certitude that truth is in some way accessible. In consequence, to present the auto-criticism of knowledge as the problem of whether or not truth and certitude can be attained is supreme naïveté no matter what attempts are made to disguise it with a spectacular critical apparatus. If we really do doubt that our knowing faculty is truly effective, it is senseless to try to use it to measure its own value. All the subtlety of those who adopt the critical posture comes up against this inevitable obstacle: how can we possibly find out if our faculty of knowledge is ‘valid’ if, in any case, we have to use it to ‘validate’ itself in order to carry out our investigation?”[12]   


Division of the Study


This work will be divided into two parts, namely, the historical part (where we shall present the various theories of knowledge of the major philosophers throughout history) and the systematic part (where we shall examine the nature of knowledge, sense knowledge and intellectual knowledge, consciousness, the nature of truth, the ultimate criterion of truth, and the various states of the mind in confrontation with truth).












The Pre-Socratic Milesians like Thales, Anaximander and Anaximenes concentrated their philosophical efforts on cosmological issues and did not give particular attention to epistemological problems. These “naturalists” assumed that man was able to know Nature. Later on, Heraclitus of Ephesus (the forerunner of modern empiricism and phenomenalism) would stress the pre-eminence of sense knowledge, while the Eleatic Parmenides would emphasize the role of intellective knowledge in the apprehension of the truly real.

Skepticism and relativism would come to the foreground with the Sophists (i.e., Protagoras, Gorgias), providing fertile ground for the investigation of various epistemological questions. However, the real inventor of the science of epistemology would be Plato. It was this Athenian, one of the greatest philosophers of all time, who would deal extensively with the basic questions tackled by epistemology, namely, the nature of knowledge, the validity of sense knowledge and intellectual knowledge, and the relations between opinion, knowledge and belief. However, Plato’s doctrine of knowledge was not without many errors. Aristotle would later correct his teacher’s exaggerated realism (the universals ideas exist as universals in reality) with his own moderate realism (universals exist in the mind and the things which they represent exist in reality as particular and individual. Moderate realism was later to be adopted and fully developed by St. Thomas Aquinas). With the death of Aristotle and the rise of Hellenistic philosophies we see the return to sensism, phenomenalism and relativism, as seen in the philosophies of Epicureanism and Skepticism. Though their rival philosophy during this age was Stoicism, this latter philosophy was in large part also empiricist in inspiration.           

Ancient Greek philosophy ends with Neo-Platonism, founded by Ammonius Saccas, but whose greatest exponent was Plotinus. Plotinus stressed the pre-eminence of the soul over the body and emphasized perception and knowledge as functions proper to the soul. Activities like perception and memory are functions of the soul. The goal of the intellect is the contemplation of the Forms (at the summit of the hierarchy of Forms being the One) and union with the One by means of the ascetical path, terminating in ecstasy.




A sensist phenomenalist, Heraclitus of Ephesus (c. 540- c. 480 B.C.) was the first thinker to delve into the nature of change and becoming in the world. He is known as the philosopher of change for what exists for him is not being but becoming; change is the only reality. This is the result of his over-reliance on sense knowledge (which senses the changing accidents) and his serious undermining of the proper role of intellectual knowledge in the knowledge of reality (against sensism, realism holds that the intellect is able to reach the nature of the substance which remains stable throughout the mutability of its accidents; i.e., a dog is a dog even though the year before it was five pounds less and today it is five pounds more in weight). In keeping with the materialistic orientation of pre-Socratic philosophy, Heraclitus states that the first principle of universal becoming, of universal change, is fire, since it is at once the most elusive and the most active of elements and is perpetually in movement. Change or becoming have their proper cause and law which he calls the logos (or universal reason), which he identifies with fire. Maintaining that all reality is pure change or becoming, that nothing is and everything changes, that whatever is, insofar as it is, is not, since it is subject to change, he denied what was later to be called the principle of non-contradiction (which states that it is impossible to be and not to be at the same time and in the same respect). Heraclitus’ philosophy of pure flux says that “we go down, and we do not go down into the same river; we are, and we are not; sea water is at once the purest and the most tainted; good and evil are one and the same thing.”[13] Because of his philosophy of pure change, which denied the essential stability of things (their stable essences and their substances, something Hegel and Bergson would later subscribe to thousands of years later), everything would dissolve into a single reality, the One (which, for him, is divine). Thus, Heraclitus’ philosophy of change is also a radical philosophy of monism and pantheism.    




Though Aristotle was the first systematizer of the science of metaphysics, Parmenides (c. 520-c. 440 B.C.) is considered to be the first metaphysician, for it was he who first placed being on philosophy’s center stage. A decided intellectualist and despiser of sense knowledge,[14] Parmenides discovered that betweeen being and non-being there existed a radical distinction: being is and non-being is not ; being is thinkable and non-being cannot be thought of. He was the first formulator of the principle of non-contradiction, holding that being is and non-being is not (a principle which Aristotle would later perfect).

Though he affirms that being is the true object of the intellect (in this he is credited for establishing, at the birth birth of Greek philosophy, the correspondence between being and intellect), Parmenides went to excess, holding that this being (which is One) is the only reality, thus denying all multiplicity in the world. Change, motion, becoming, and multiplicity are all illusory for him. There exists only Being, which is one, perfect, absolute, immutable, infinite and eternal. Thus, he ends up a monist and a pantheist, attributing that which is proper to the Supreme Being, God, to the being of the world. Jacques Maritain explains that “as he contemplated pure being, he (Parmenides) perceived that this being is completely one, absolute, immutable, eternal, without becoming, incorruptible, indivisible, whole and entire in its unity, in everything equal to itself, infinite, and containing in itself every perfection. But while he thus discovered the attributes of him who is, he refused to admit that any other being could exist, and rejected as a scandal to the reason the being mingled with non-entity, because produced from nothingness, of every creature. He was thus led so far astray that he ascribed to the being of the world that which belongs only to uncreated being.”[15]

Parmenides wanted to re-establish the truth of being in opposition to the philosophy of pure becoming. But he understood his principle “Being is, non-being is not” in a rigid, inflexible manner and rejected every non-being, including every relative non-being. Thus, he concluded all limitation, multiplicity and change to be impossible and, therefore, all reality was but a single, homogeneous, immobile being. “Parmenides, reaching the opposite pole to Heraclitus, fixed, as he did, once for all one of the extreme limits of speculation and error, and proved that every philosophy of pure being, for the very reason that it denies that kind of non-being which Aristotle termed potentiality and which necessarily belongs to everything created, is obliged to absorb all being in absolute being, and leads therefore to monism or pantheism no less inevitably than the philosophy of pure becoming.”[16]

Parmenides’ notion of being was not analogical but univocal. He failed to draw a distinction between the infinite and the finite. A correct solution to the problem of Parmenides’ monism lies in the doctrine of act and potency later developed by Aristotle and in the teaching that being is not univocal but analogical: “Thus all the difficulties raised by Parmenides could easily be solved by dividing Being into two kinds, two realities, two essentially different realizations (rationes simpliciter diversae secundum quid eaedem) of the same analogical idea of Being: 1. Being realized in a supreme and infinite degree, i.e. the essentially existent, the purely actual – ipsum esse subsistens – to which are applicable all Parmenides’ metaphysical inferences, provided all material elements be excluded ; and 2. Being realized in varyingly limited degrees, in things affected more or less with potentiality, the objects of sense experience. In regard to beings of this kind, the Eleatic arguments have no validity.”[17]


The Sophists


Originally, the term “Sophist” meant simply “wiseman,” or “possessor of wisdom,” but it later came to have a negative, derogatory connotation: “‘Sophist’ is said of those who make use of reason captiously in order to try to weaken and hide the truth, and others in order to attempt to strengthen false reasoning giving it the appearance of the truth.”[18] Those who described Sophism in this negative sense were the three great defenders of objective truth and the three greatest enemies of the Sophists, namely, Socrates, Plato, and Aristotle. Plato gives us a description of the Sophist in his dialogue by that name: “First, I believe, he was found to be a paid hunter after the young and wealthy…secondly a kind of merchant in articles of knowledge …third did he not turn up as a retailer of these same articles of knowledge?…and in the fourth place we found he was a seller of his own productions of knowledge…and fifth he was an athelete in contests of words, who had taken for his own the art of disputation…”[19] The author of the Memorable Words of Socrates, Xenophon, also writes of the Sophists in a negative way: “For to offer one’s beauty for money to all comers is called prostitution…So it is with wisdom. Those who offer it to all comers for money are known as sophists, prostitutors of wisdom.”[20] “The sophists speak in order to deceive, and they write for their own gain, and in no way to be of use to anyone…”[21] Aristotle likewise speaks of the pseudo-wisdom of the Sophists, writing: “The art of the sophist is the semblance of wisdom without the reality, and the sophist is one who makes money from an apparent but unreal wisdom.”[22]

The Sophists were characterized by their great mistrust of metaphysics. They considered ontological speculation illusory, a “show” (a term also employed by the empiricist Francis Bacon at the beginning of the seventeenth century A.D., whose famous phrase “knowledge is power” would have appealed very much to the Sophists). Like Bacon, the Sophists pragmatically affirmed the primacy of praxis over theory, action over contemplation, the horizontal over the vertical outlook in life. In his book Leisure the Basis of Culture, the German Thomist philosopher Josef Pieper (1904-1997) points out that “there is a direct path from Francis Bacon, who said, ‘Knowledge is power,’ that the value of all knowing lies in the provision of human life with new discoveries and helps, to Descartes, who in his Discourse on Method explicitly formulated the polemical program to replace the old ‘theoretical’ philosophy with a new ‘practical’ one, through which we make ourselves ‘the Lords and Masters of nature’[23] – from there the road leads directly into the well-known saying of Karl Marx, that up until his time philosophy saw its task as one of interpreting the world, but that now its task was to change the world. This is the path along which the self-destruction of philosophy has travelled: through the destruction of its theoretical character, a destruction which in turn rests upon habitually seeing the world as the raw material of human activity. When the world is no longer looked upon as creation, there can no longer be theoria in the full sense. And with the fall of theoria, the freedom of philosophy falls as well, and what comes in its place is the functionalizing, the making it into something ‘practical,’ oriented toward a legitimation by its social function; what comes to the fore is the working character of philosophy, or of philosophy so-called. Meanwhile, our thesis (which can now be more clearly formulated), maintains that it is of the nature of the philosophical act, to transcend the world of work (in fact, it expressly presumes it as something necessary), but it maintains that true philosophy rests upon the belief that the real wealth of man lies not in the satisfaction of his necessities, nor, again, in ‘becoming lords and masters of nature,’ but rather in being able to understand what is – the whole of what is. Ancient philosophy says that this is the utmost fulfillment to which we can attain: that the whole order of real things be registered in our soul[24] – a conception which in Christian tradition was taken up into the concept of the beatific vision: ‘What do they not see, who look upon Him, Who sees all?’[25][26]

Instead of seeking wisdom and loving truth, as the true philosopher ought to do, the Sophists concentrated their efforts on dialectics, rhetoric, and eloquence in order to possess power, wealth and honors. Maritain describes them: “They did not seek truth. Since the sole aim of their intellectual activity was to convince themselves and others of their own superiority, they inevitably came to consider as the most desirable form of knowledge the art of refuting and disproving by skillful arguments, for with men and children alike destruction is the easiest method of displaying their strength, and the art of arguing with equal probability the pros and cons of every question, another proof of acumen and skill. That is to say, in their hands knowledge altogether lost sight of its true purpose, and what with their predecessors was simply a lack of intellectual discipline became with them the deliberate intention to employ concepts without the least regard for that delicate precision which they demand, but for the pure pleasure of playing them off one against the other – an intellectual game of conceptual counters devoid of solid significance. Hence their sophisms or quibbles. Their ethics were of a piece. Every law imposed upon man they declared to be an arbitrary convention, and the virtue they taught was in the last resort either the art of success, or what our modern Nietzscheans call the will to power. Thus, of the spirit which had inspired the lofty intellectual ambitions of the preceding age, the Sophists retained only the pride of knowledge; the love of truth they had lost. More ardently than their predecessors they desired to achieve greatness through knowledge, but they no longer sought reality. If we may use the expression, they believed in knowledge without believing in truth. A similar phenomenon has recurred since in the history of thought and on a far greater scale. Under these conditions the sole conclusion which Sophism could reach was what is termed relativism or scepticism.”[27]

Sophism’s main exponents were Protagoras and Gorgias. Protagoras (c. 481–c. 411 B.C.) elaborated an essentially relativistic and anthropocentric gnoseology and ethical system. He is famous for the axiom that has become the cornerstone of Western relativism, namely, that “man is the measure of all things, of the things that are that they are, and of the things that are not, that they are not,”[28] by which he meant that all was relative to the dispositions of the individual human subject (and not relative to ‘universal man’ as Kantian transcendental idealism would have it), the “truth” being that which appears true to him. “By ‘measure’ Protagoras must have meant the norm of judgment, while by ‘the things’ he must have meant all facts in general. The axiom has very quickly become famous and it is considered and is actually almost the magna charta of western relativism. Protagoras undoubtedly intended, by using the principle of man-measure, to deny that an absolute criterion exists by which to discriminate between being and not being, truth and falsity, and in general every value. The criterion is only relative, it is the man, the individual man.”[29] Giovanni Reale’s interpretation – that the individual man, and not the generic or universal man, is what Protagoras means when he says that “man is the measure of all things” – finds confirmation in the writings of the Stagirite[30] as well as in the works of Sextus Empiricus, who writes that “Protagoras only admits that which appears to single individuals, and in that way he introduces the principle of relativity.”[31]         

Taking his cue from the philosopher of change Heraclitus, Protagoras maintained that all things are in perpetual flux and becoming; there are no fixed natures. Protagoras’ own sensism could only lead him to skepticism: nothing can be known with certainty, he holds; it is the individual man who is the final arbiter of the truth of the object, determining it according to his mode of knowing it. His moral sytem is decidedly pragmatic and utilitarian: good and evil are determined by crass utility and convenience for oneself. Though Protagoras certainly believed that truth and falsity are entirely relative and subjectivistic, he did maintain a certain utilitarian objectivity, that is, that man is measured by utility (in an objective though not absolute way). As regards religious belief Protagoras was an agnostic: “As for the gods, it is impossible for me to affirm whether they exist or not.”[32] His agnosticism was a consequence of his sensism.     

Gorgias (c. 484–c. 375 B.C.) rejected the anthropocentric relativism of Protagoras for an even more radically skeptical and nihilist view of reality, negating the existence of being as well as the correspondence between being and thought. His three fundamental theses are: “First: nothing exists; Second: if anything existed, it cannot be known by man; Third: if it can be known, it cannot be transmitted and explained to others.”[33] Not having any faith whatsoever in philosophy as a legitimate science, Gorgias concentrated his efforts on rhetoric; although words, for him, have no truth content they can be utilized in order to control and manipulate the minds of others.      

Critique of Sophistic Relativism. The anthropocentric relativism of the Sophists should be rejected as being contrary to the first principles of knowledge (i.e., the principle of non-contradiction, identity, sufficient reason) and thus illogical and unsound, being fundamentally contrary to right reason, as Paul Glenn explains: “Relativism is wholly inadmissible, and this upon three counts: it is self-contradictory; it stands in conflict with reason; its arguments are not sound. 1. Relativism is self-contradictory. Relativism is offered as a true philosophical doctrine. But relativism is a doctrine that maintains that all truth changes. Hence, relativism itself must change. It may cease to be true; it may have long since ceased to be true; certainly some day it will cease to be true. Hence, relativism is a theory that destroys itself. If the relativist insists that his doctrine is constant and absolute, then he is no longer a relativist, for he has admitted the unchanging character of at least one truth – something that relativism will not allow him to do. We, therefore, reject relativism as self-contradictory in teaching as an unchangingly true doctrine that all truth changes.

“2. Relativism conflicts with reason. Indeed, reasoning becomes impossible if relativism is admitted. For reasoning depends upon the constant and unchanging value of ideas, of mental terms. Unless I know what ‘truth’ means, and must always mean, how can I discuss the relativity of truth? How can I even assert that truth changes, if I have no constant and unchanging idea of what it is that changes? And how can I talk of ‘change,’ unless I know the absolute meaning of the verb ‘to change’? How can I say that what was false may become true, if I have no unchanging concept of what is meant by false and true? And if I do not know the absolute and unchanging meaning of good and evil, how can I speak of one changing into the other?

“Again, there are truths which the mind recognizes and expresses in judgments that are absolute, necessary, unchanging. In the ideal order, we have judgments such as, ‘The whole is greater than its part’; ‘A thing cannot be at once existent and non-existent’; ‘An effect demands an adequate cause or sum of causes.’ In these judgments reason apprehends the predicate as something demanded by the very nature of the subject, and hence as something always predicable of that subject, and of unchanging necessity predicable of that subject. Yet this manifest requirement of reason is contradicted by relativism. In the order of concrete fact there are judgments such as ‘This is a hot day,’ or ‘The fire burns brightly,’ in which the predicate is exacted by the subject by necessity of fact. That the day grows cooler towards evening, that the fire presently burns low, does not give the lie to the fact that, at the moment of actual and justifiable predication, the fire does burn brightly, and the day is hot. Such judgments, if true at all, are hypothetically changeless, that is, they are changeless in the actual circumstances of the predication. Thus, if today is hot, it will be forever and forever true that today was hot. A short time ago I could have said with truth, ‘Herbert Hoover is President of the United States.’ At the present time I cannot make the same statement with truth. Does this mean that truth changes? Not at all. It only means that concrete facts – and Presidents – change. The statement was true when made, and it will be forever true, given the conditions at the time of its utterance. The statement really means: ‘At a point of time (which is now for the speaker, to come for ages past, and then for subsequent times) Herbert Hoover is President.’ No one denies that there is change in things; indeed, there is nothing in this world of concrete contingent realities that does not change; all things in our bodily universe have their origin, their cessation; their time of waxing and of waning; their exits and their entrances. But there is no change, there can be no change, in truth. Once true, forever true. Relativism stands in contradiction to this doctrine; this doctrine is a requirement of reason; therefore, relativism stands in opposition to reason, and is inadmissible.

“3. Relativism rests upon unsound arguments. Relativists aver that such a judgment as ‘This is a hot day’ is true for the speaker at the moment it is uttered, but is not true for him very long, for the day grows cooler; nor is it true for all men, for some men live in cold regions. We have seen the invalid character of this argument. The statement is true by necessity of fact, and the fact is determined by the circumstances and material conditions of the moment the judgment is uttered. The change in these circumstances, and the contemporaneous existence of different circumstances, make no difference at all in the changeless truth that ‘here and now, it is a hot day.’”[34]    




One of the most influential philosophers of all time, the Athenian Plato (427-347 B.C.) is most known for his theory of Ideas (also called the doctrine of Forms). He was an ultra-realist (exaggerated realist), believing that Ideas really exist in reality as universal. Plato taught, for example, that if we are able to talk about sacrifice and explain its timeless demands on persons in a way that transcends the individuals who ought to live by this admirable virtue, it is because sacrifice really exists in itself as an eternal, absolute and immutable form, perceivable not by the senses but by the intellect.

The things in the world that our senses behold, Plato teaches, are copies or replicas of their exemplars, the Ideas, which are eternal, immutable, and absolute. The world of the Ideas, and not the world that we see around us by means of the senses, constitutes the true world. Our senses can only give us opinion (doxa), whereas our intellect, contemplating the Ideas, gives us true knowledge or science (epistème).

The Theory of Ideas or Forms. Plato’s philosophy is centered round and dominated by his Doctrine of Ideas or Forms, which may be summed up in the following principle: The specific object of human knowledge is the real world of Ideas, of which the world of the senses is but the shadow or the copy. Real being, according to our philosopher, is not to be found in the particular sensible objects that make up what we call Nature, but rather in the universal essences which are the objects, not of sense, but of the conceptions of the intellect. Particular beautiful persons or things, for example, are not real beauty; only the universal essence or Idea Beauty is. Particular sensible things only imitate reality insofar as they imitate the Ideas; particular horses are only imitations of the one, eternal, universal Horse, or the Idea Horse. The very essence of Plato’s Doctrine of Ideas is that the universals are the true realities and the particulars, the individual things that we experience in Nature, are only half-real imitations of these true realities. Plato’s Ideas or Forms are not something in our mind but are primarily objective realities in themselves. They are objective universal essences existing apart from the phenomena of the sense world and apart from our conceptual representations. How did he arrive at such a false conclusion, namely, that universal Ideas really exist as universals in a world of Forms, apart from the human mind? Maritain notes that “failing to analyze with sufficient accuracy the nature of our ideas and the process of abstraction, and applying too hastily his guiding principle, that whatever exists in things by participation must somewhere exist in the pure state, Plato arrived at the conclusion that there exists in a supra-sensible world a host of models or archetypes, immaterial, immutable, eternal, man in general or man in himself, triangle in itself, virtue in itself, etc. These he termed ideas, which are the object apprehended by the intellect, the faculty which attains truth – that is to say, they are reality.”[35] Plato’s system can be classified as an exaggerated realism which retains that universals are real things existing by themselves. Universal concepts would exist independently of the individuals they are predicated of.
To correct Plato’s error of exaggerated realism we have the position of moderate realism espoused by the likes of Aristotle and St. Thomas. “Our words and universal concepts no doubt signify certain natures, but these natures do not exist in themselves but are individualized in things. Only individual beings exist in reality, for the things that exist cannot be predicated of another. Universality is a property only of our abstract concepts; it is by virtue of their universality that they are predicable of many. ‘Something is a universal not only because it can be predicated of many, but also because what is signified by its name can be found in many.’[36] For example, justice is a virtue proper to human nature; hence, the foundation of its demands is found in every individual subject who possesses that nature. The common nature that is possessed by many individual beings is common not numerically but formally. If I write ‘A’ twice – ‘A’ and ‘A’ –, I reproduce the same form in two numerically distinct letters; in the same way, human nature is actualized in John, Frederick, and Timothy, in such a way that numerically, each one has his own individual nature. For a nature to be multiplied in several individuals, the form must be capable of being received in several material subjects. The answer to the problem of the universals is, therefore, linked to the hylemorphic composition (the union of matter and form) of material beings (John and Peter are both men because they share the same nature; but they are distinct individual men because the formal principle of that nature has been received in different matters). As regards accidental properties, the answer of moderate realism involves the distinction between substance and accident (the property ‘yellow’ can be multiplied if there are many substances capable of receiving it).”[37]     

A thing exists intentionally in the intellect as a universal, but exists really in the extra-mental world as an individual. That which we apprehend by our ideas as a universal really exists, but only in the extra-mental objects themselves and therefore individuated – not as a universal. To give an example: the human nature found alike in Paul, Billy, Edward and Bobby really exists, but it has no existence outside the mind except in these individual subjects and as identical with them. Human nature has no separate existence, does not exist in itself in reality as a universal Idea.

To summarize Plato’s error, he believed that that which our ideas present to us as a universal really exists extra-mentally as a universal. To correct this, moderate realism holds that that which our ideas present to us as a universal does not exist outside the mind as a universal but rather individuated.

Knowledge as Remembrance. Unlike the Aristotelian theory of knowledge which derives universal concepts from sense images by means of abstraction, Plato instead believes that knowledge is basically reminiscence (remembrance or anamnesis). He teaches that the soul, going back many reincarnations ago, at one point beheld the Ideas in the world of the Forms. But because of some sin or crime done in a previous life the soul was punished by being trapped in the prison of the body where the knowledge of the Ideas became dormant. The soul recalls this knowledge when it encounters material things, which are faint replicas of the unchanging world of the Ideas.

Bittle remarks that Aristotle opposes Plato’s theory of reminiscence “on the grounds that it is poetic and fantastic and contrary to the testimony of consciousness. If we actually had a former existence, the awakening of the innate universal ideas should also revive the memory of this previous existence itself. But we have no such memory. The theory is pure assumption on the part of Plato.”[38]   

Degrees of Knowledge. For Plato, there are two grades of sense knowledge, namely, eikasía and pístis, and two grades of intellectual knowledge: diánoia and nóesis. Eikasía consists in the apprehension of images in the world which our senses behold for us. Pístis consists in the perception of sensible things, accompanied by a faith in the reality (albeit inferior) of the objects apprehended by the senses. In diánoia we have a knowledge of mathematical entities by means of reason. Lastly, in nóesis we have a direct and intuitive knowledge of the Ideas. It is the task of philosophy to lead one from eikasía to the highest degree of knolwedge in nóesis where one has a true knowledge of reality. Unfortunately, the majority of men languish in the state of eikasía, whereas only the few commited lovers of wisdom (the philosophers) manage to reach a knowledge of the truth in nóesis, the contemplation of the intelligible world of the Ideas.      




If Plato was gnoseologically an ultra-realist, Aristotle (384-322 B.C., also known as the Stagirite) maintained the epistemological position of moderate realism (he held that ideas were universal in the mind, their “reality” stopping there, while the things that these ideas represent are individual and concrete in reality). If the former’s method was above all deductive (as in mathematics), the latter’s was primarily, but not exclusively, inductive (as in chemistry, biology, etc). While Plato’s gnoseology is otherworldly (the true world contemplated by the intellect being the world of the Ideas, while the material world grasped by our senses is deemed an inferior “reality,” lying midway between being and non-being), Aristotle’s philosophy of knowledge is solidly rooted in empirical reality, and thus, his realism is more conducive to the development of the empirical sciences than the whole Platonic and Neo-Platonic ultra-realist tradition, which plays down on the role of the senses and empirical knowledge.

For the Stagirite, human knowledge is not essentially anamnesis (the reminiscence or remembrance of things past when the soul once beheld the Ideas), but rather the result of the harmonious interworking of the senses (the five external senses of sight, hearing, taste, touch and smell, and the four interior senses of common sense, imagination, memory and the cogitative) and intellect in their grasping of extra-mental reality. All knowledge, for Aristotle, is gotten initially through the senses. There are no innate ideas (as is the case with Plato, and later on with the rationalist Descartes, the father of modern philosophy). A newly born baby is born with a blank slate, a tabula rasa (not having previous knowledge from a former life); the infant begins to know initially through his or her senses.

A man’s sense knowledge is the material for his intellectual knowledge. He is able to abstract from his sense images (by the power of his agent intellect), to eventually produce universal ideas (concepts, the fruit of his potential or passive intellect), which are mental signs of the essences of things. In abstraction the mind, in particular the agent intellect (which is capacity to abstract) works on the sense image (which is the expressed species of a sensible order) denuding it of all its individuating characteristics, to produce the abstracted nature (which is the impressed species of an intelligible order). The abstracted nature, in turn, activates the potential intellect (which is the power of the mind to understand) which expresses itself with the universal concept (the expressed species of an intelligible order). Undoubtedly, the central doctrine in Aristotle’s gnoseology is that of abstraction and upon this he bases his three level partition of the sciences. In the first degree of abstraction (the abstraction from sensible matter) one finds the particular science of physics; in the second degree of abstraction (the abstraction from intelligible matter – space and time) one finds the science of mathematics; and in the third degree of abstraction (where there is the abstraction from all genera of matter) one finds the science of metaphysics (which he calls ‘first philosophy’).   

The Principle of Non-Contradiction. Aristotle also defended the first of all principles, namely, the principle of non-contradiction,[39] from all manner of skeptical attacks. As being is the first notion that our intelligence grasps, and which is implied in any consequent notion, there is also an intellectual judgment which comes naturally first and which is presupposed by all other consequent judgments. This intellectual judgment is this:“It is impossible to be and not be at the same time and in the same respect.” This first judgment is called the principle of non-contradiction for it expresses the most basic condition of things, namely, that they cannot be self-contradictory. Such a principle is founded upon being and expresses the consistency of being and its opposition to non-being. 

There are different ways of expressing this first principle. It is above all a judgment that concerns reality itself. Hence, the more profound formulations of the principle of non-contradiction are metaphysical in nature. For example, the Stagirite states in the fourth book of his Metaphysics that “it is impossible for one and the same thing to be and not to be,”[40] and further on, that “it is impossible for a thing to be and at the same time not to be.”[41]

The principle of non-contradiction is the supreme law of reality and not just a simple postulate or axiom of our mind. But, since the mind of man is geared to know reality as such, the principle of non-contradiction is, in a derivative way, the first and supreme law of logic. Violate this supreme law and one collapses into a state of mental anarchy. Since the first principle of reality is also the first principle of thought we are able to say that “we cannot both affirm and deny something of the same subject at the same time and in the same sense,” as well as to state that “contradictory propositions about the same subject cannot be simultaneously true.” The human mind is subject to the principle of non-contradiction: it cannot know being as self-contradictory precisely because being cannot be self-contradictory. If our mind attempts to deny the principle of non-contradiction our reasoning falls into absurdities.

In the Metaphysics, Aristotle replies to those who would be so foolish as to negate the principle of non-contradiction, writing that “in order to deny this principle, one has to reject all meaning in language. If ‘man’ were the same as ‘non-man’, it would not, in fact, mean anything at all. Any word would signify all things and would not, therefore, denote anything; everything would be the same. Consequently, all communication or understanding between persons would be impossible. Thus, whenever anyone says a word, he is already acknowledging the principle of non-contradiction, since he undoubtedly wants the word to mean something definite and distinct from its opposite. Otherwise, he would not even speak…Anyone who rejects this first principle should behave like a plant, since even animals move in order to attain an objective which they prefer over others, as when they seek food.”[42] “Besides, denying this principle in fact implies accepting it, since in rejecting it, a person acknowledges that affirming and denying are not the same. If a person maintains that the principle of non-contradiction is false, he already admits that being true and being false are not the same, thereby accepting the very principle he wishes to eliminate.”[43] 

The principle of non-contradiction is naturally and spontaneously known by all men through experience and is self-evident to all. Since it is the first judgment, this first principle cannot be demonstrated by means of other truths prior to it. When a truth is self-evident, it is neither necessary nor possible to prove it; only something which is not immediately evident requires proof. That the principle of non-contradiction is not demonstrable because of its self-evidence is not a sign of its imperfection; rather, it is a sign of its perfection.

Garrigou-Lagrange summarizes for us Aristotle’s eight principal reasons for defending the necessity and objective validity of the principle of non-contradiction: “(1) to deny this necessity and this validity would be to deprive words of their fixed meaning and to render speech useless; (2) all idea of the reality of an essence, or thing or substance as such, would have to be abandoned; there would be only a becoming without anything which is on the way of becoming; it would be like saying that there can be a flux without a fluid, a flight without a bird, a dream without a dreamer; (3) there would no longer be any distinction between things, between a galley, a wall, and a man; (4) it would mean the destruction of all truth, for truth follows being; (5) it would destroy all thought, even all opinion ; for its very affirmation would be a negation. It would not be an opinion which Heraclitus had when he affirmed that contradictories were true at the same time; (6) it would mean the destruction of all desire and all hatred ; there would be only absolute indifference, for there would be no distinction between good and evil ; there would be no reason why we should act; (7) it would no longer be possible to distinguish degrees of error, everything would be equally false and true at the same time; (8) it would put an end to the very notion of becoming; for there would be no distinction between the beginning and the end of a movement; the first would already be the second, and any transition from one state to another would be impossible. Moreover, ‘becoming’ could not be explained by any of the four causes. There would be no subject of becoming; the process would be without any efficient or final cause, and without specification, and it would be both attraction and repulsion, concretion as well as fusion.”[44]




In general, the fundamental thesis of philosophical skepticism is that man can never know the truth. He cannot affirm anything with certainty and must rest content with the position of epoké, that is, a suspension of judgment. Ancient skepticism’s principal exponents are Pyrrho (generally held to be the founder of the skeptic school), Carneades and Sextus Empiricus. Skepticism attained a large diffusion during the Hellenistic period and was, ironically, even the official doctrine of the Platonic Academy for some time.

Pyrrho (360–270 B.C.) hailed from Elis and was said to have accompanied Alexander the Great on his military expedition to India. He was greatly influenced by three previous philosophies: Democritean materialism and sensism, Sophistic relativism and Cyrenaic gnoseology. Though Diogenes Laertius writes that Pyrrho left no writings, his philosophical views are preserved for us by his pupil Timon of Phlius (c. 320-230 B.C.).   

Pyrrho taught a radical brand of skepticism, holding that man must suspend his judgment on all things and that such a suspension is the foundation of peace of soul (ataraxia). The only legitimate attitude that man can take in front of reality is the suspension of all judgment (epoké). One can never affirm if something is true or false, good or bad, just and unjust, and so forth. 

Carneades (219–129 B.C.) was born in Cyrene, went to Athens where he studied the various philosophical schools then in vogue (especially the thought of Chrysippus), and eventually found his way into the Platonic Academy. When Hegesius died, Carneades became scholarch of the Academy and eventually founder of the Third Platonic Academy (also called the New Academy). He was sent to Rome as ambassador in 156/5 B.C., together with the scholarchs Critolaus of the Lyceaum and Diogenes of Babylonia. Carneades died at the old age of ninety.  

Carneades moderated Pyrrho’s radical skepticism, proposing a skepticism which acknowledges the possibility for man to know what is probable, even though he is, in the end, incapable of attaining any truth whatsoever. The wise man, for him, would be the person who, although knowing that truth is unattainable, nevertheless eagerly seeks ever closer approximations to it. In the practical sphere of action, Carneades taught that the good man was he who lived closer to the truth and that in his actions probability is to be the practical criterion for action: “Such was Carneades’ reasoning against the other philosophers, demonstrating that no criterion of truth was available. But faced with the need to give some criterion for the conduct of human life and the acquisition of happiness, he was obliged in a way to state his position on this question. He took probable representations as the criterion for such conduct, representations that involve no contradiction and which have been studied from all points of view.”[45]     

Sextus Empiricus (180–220 A.D.), philosopher as well as medical doctor, was the last major exponent of skepticism. He developed quite a complete system of skepticism. He believed that there was no possibility whatsoever for absolutely certain knowledge: one cannot pronounce upon precise assertions regarding the nature of “exterior” things. Sextus Empiricus denied the validity of the Aristotelian syllogism, the principle of causality, and all the dogmatic doctrines of the preceding philosophers. However, if absolutely certain knowledge must be combatted as dogmatism, the research that our minds conduct in the knowledge of phenomena is useful for experience always gives us the possibility of bettering our knowing powers.

Critique of Skepticism. The skeptical professor can deny the certainty that reality exists, but the minute he steps out of the classroom he acts like a realist (i.e., he holds as certain that the floor he is walking on really exists, that the car he is driving really exists, and that the fourteen-wheeler truck speeding towards him really exists, and so forth. If he denied these facts he would be dead). Therefore, skepticism is a practical impossibility (unworkable in action), as Bittle explains: “Skepticism is a practical impossibility. No sane human being can live without certitude of a practical kind. Even the most confirmed skeptic, no matter how many reasons of a theoretical and speculative nature he may have for doubting the possibility of genuine certitude, cannot lead a human life without denying his skeptical theory all day long in his conduct. His life shows that he is certain of very many things: the physical world, with its seasons and changes of weather, with its periods of day and night, with its differences of time and space relations; his own body, in all its concrete reality, in its conditions of health and sickness, in its physical needs of food, drink, and sleep; the existence and knowability of other people and other minds, some of whom agree with him while others disagree, and whom he communicates by means of conversation and writing, and whom he tries to convince of the truth of universal doubt. The story is told of Pyrrho the Skeptic that, when chased one day by a rabid dog, he ran for safety without allowing his skepticism to exercise its doubt about the existence and viciousness of the brute. When the bystanders laughed at him and ridiculed him for the inconsistency of his action, he is said to have made the sage remark (completely out of keeping with his theory): ‘It is difficult to get away entirely from human nature.’ After all, he could not doubt, in an untheoretical moment, that his body and the dog were real objects. This discrepancy between fact and theory, between life and philosophic system, between practical certitude and speculative doubt, is an incontrovertible proof that universal doubt is an impossibility except as a mere formulation of the mind. When facts and theories clash and contradict each other in such a transparent fashion, the sane man will not deny the facts and cling to his theories, but will realize that something is radically wrong with his views. Facts cannot be denied. To persist in universal skepticism in the face of a million contradicting facts of life bespeaks either insanity or stubbornness of mind. When the inconsistency between life and theory cannot be harmonized, it will not do to deny life, because that would be ridiculous; the theory must be abandoned as essentially faulty. Universal skepticism, therefore, must be rejected as a practical impossibility.”[46]

Skepticism is not only a practical impossibility but also a theoretical or speculative absurdity. If our skeptical professor maintains that he cannot be certain about anything, the very judgment that he pronounces is already a certainty. He is certain that there cannot be any certainty about anything. Even though his certainty is erroneous, it, nevertheless, is a certainty. Bittle states: “One simply cannot doubt all things and principles, not even in a speculative way. The skeptics prove this by their own intellectual inconsistencies; and inconsistencies are the stigma of every false theory. Any normal person will realize the inherent contradiction of universal skepticism, if it is real and genuine, upon considering the following points:

“Skeptics contend that real certitude in knowledge is impossible, so that we must always suspend our judgment because of a real doubt as to the truth of our judgment. This, in their view, is the only logical and rational thing to do. But then, they have at least arrived at this truth that we cannot be certain; and there is at least no doubt that we must doubt. Therefore, even skeptics possess certitude about something, and their fundamental tenet of universal doubt is involved in a contradiction.

“Skeptics claim we must suspend our judgment regarding any question, because we might fall into error. But error is the opposite of truth. Consequently, they acknowledge that there is a difference between ‘truth’ and ‘error,’ and the two are not the same. Similarly, they must admit that ‘certitude’ and ‘doubt’ are not the same; otherwise, why should we doubt rather than be certain? Their very insistence on this difference shows plainly that they recognize the fact that something cannot be true and erroneous, certain and doubtful, at the same time. But thereby they surreptitiously admit the certainty of the truth of the principle of non-contradiction.

“Skeptics either have valid reasons for their universal doubting, or they have no valid reasons for it. If they have valid reasons, they surely know something that is valid, and they no longer are real skeptics. If they have no valid reasons, they have no reason to doubt. In the first case their position is inconsistent, and in the second case their position is irrational. Whichever way they turn, their position is untenable.

“Skeptics, in defending the necessity of universal doubt, must naturally be conscious of their doubt and its necessity; for, if they were not conscious of this, they could neither be aware of their doubt nor speak of it. Consequently, they rely upon the testimony of their consciousness as a source of valid knowledge. But that involves certitude regarding their own existence and person and regarding the trustworthiness of consciousness. They cannot, in consistency, cast a doubt upon the testimony of consciousness, because the argument of St. Augustine, in speaking to the skeptics, would apply to them: ‘If I err, I exist. For one, who does not exist, cannot err; and by the very fact that I err, I exist. Since, therefore, I exist, if I err, how can I err about my existence, when it is certain that I exist if I err?’[47] That the skeptic must admit and acknowledge the certain existence of various states of his own consciousness, has been pointed out by St. Augustine in another passage, marked by a keen appreciation of the facts in the case: ‘If he doubts, he lives; if he doubts, he remembers why he doubts; if he doubts, he understands that he doubts; if he doubts, he wants to be certain; if he doubts, he thinks; if he doubts, he knows that he does not know; if he doubts, he judges that he must not give a hasty consent.’[48] Notwithstanding their claim to universal doubt, therefore, the skeptics by their doubting actually, though inconsistently, express certitude concerning a great number of facts and principles. Universal skepticism collapses under the weight of its own folly. And thus we see that universal skepticism is a philosophic absurdity.”[49]








Saint Augustine


Refutation of Skepticism. At first a Manichean and then an academic skeptic for a brief period while in Rome, Augustine of Hippo (354-430) later on became, as a Catholic Christian and proponent of a modified Neo-Platonist philosophy, a fierce critic of skepticism, holding against the academic skeptics that we can in fact know objective truths. We can know, for example, the first of all principles (the principle of non-contradiction) with certainty.[50] He notes that even the sceptics are certain of a number of truths, such as, for example, the fact that of two disjunctive propositions one must be true and the other false. One is also certain of one’s existence, for even if one doubts his own existence, the doubt itself is a proof of existence. He notes that even if one falls into error, one’s being mistaken shows that one exists. Si fallor, sum (if I am mistaken, I exist). “If you did not exist, you could not be deceived in anything.”[51] He states that “I am most certain of my being, knowing and loving; nor do I fear the arguments against these truths by the academics who say, ‘and what if you deceive yourself?’ If I deceive myself, that means that I am, that I exist. Certainly, he who does not exist cannot deceive himself; if I deceive myself, then through this very fact I am. Since I exist, from the moment in which I deceive myself, how can I deceive myself about my being when I am certain that I am, through the fact itself that I deceive myself? Therefore, if I would exist, I who deceive myself, even given the hypothesis that I deceive myself, I still undoubtedly do not deceive myself in knowing myself.”[52] Even doubts of the senses cannot make us doubt our existence and our being alive: “In reference to this, we must not have any fear unless we are deceived by some plausible probability, since it is certain that the man who is deceived is alive. Nor does knowledge depend on visual images which are presented from without, so that the eye is deceived in these images; for example, when an oar immersed in water seems broken and the keel seems in movement to those who navigate, or in a thousand other cases where things are not what they seem. The truth of which I am speaking is not perceptible through the eyes of the flesh. It is in virtue of internal cognition that we know we are alive…As a result, the man who asserts that he knows he is alive does not have the possibility to err or to deceive himself. Thousands of illusions of the senses may present themselves; he will not fear any of them from the moment when the man who is deceived must be alive in order to be deceived.”[53]   

Sense Knowledge. The lowest level of knowledge for Augustine, sensation consists in a spiritual act of the soul, very different from the Aristotelian doctrine of the passive reception of images from the external world initially by means of the external senses. It is an act of the soul using the organs of sense as its instruments. Sensory images are caused, he says, by the soul. “When we see a body and its image begins to exist in our soul, it is not the body that impresses the image in our soul. It is the soul itself that produces it with wonderful swiftness within itself.”[54]

Divine Illumination. As for the knowledge of the eternal truths, which is the apex of intellective knowledge, this takes place through divine illumination (a doctrine which replaces the Platonic theory of reminiscence or anamnesis). Augustine holds that we can indeed make necessary and immutable judgments and the doctrine of illumination is meant to explain such a fact. Through the divine illumination from God, when man makes a true judgment the mind is in contact with the immutable and necessary truths in the Divine Mind. Though this contact does not enable us to see the Ideas in God’s Mind, it does account for the immutability and necessity of our knowledge. Why does St. Augustine propose ‘illumination’? Because he emphasizes that truth formally considered is eternal and unchangeable, while the knowing subject, who is man, is a mutable, temporal and imperfect finite being. 

Explaining Augustine’s theory of divine illumination as entailing the showing of the truth of judgments, Gilson writes: “I listen to a man speak and tell me his ideas; I understand him, form concepts as a result and even believe him; But I do not know if he tells me the truth because I have no means of verifying what he says. Divine illumination has no role to play in this type of knowledge where the truth cannot be seen. But then my friend begins to talk about the ideas of men in general, and at once my point of view changes; I know that what he says is true and agree, or I know that it is false and disagree. It is precisely at this point that divine illumination intervenes, because here truth is at stake. It is no longer merely a question of believing the fact that so-and-so has this or that idea; we must know what men in general ought to think. Now what is the source of our certitude as to what men ought to think? It cannot be experience, because we have not seen with our eyes a certain number of minds in order to form our idea of what the mind ought to be; and besides, experience, whether external or internal, can account for the formation of the idea, but it cannot account for the necessity of the idea.[55]

“Let us take another example. I recall the walls of Carthage which I have seen, and I picture those of Alexandria which I have not seen; my mind can do this without the help of divine illumination. But then I think that the memories which recall Carthage to mind are superior to the images which represent Alexandria; this judgment of truth is based on rules at once incorruptible and inviolable, and comes from something higher than my mind: viget et claret desuper judicium veritatis (the judgment of truth shines from above strong and clear); with the necessary truth of the judgment, divine illumination had to intervene.[56] Thus there is an essential difference between the image of an object perceived, or the remembrance of it preserved in the memory, or in short any fiction of the mind conceived in the likeness of this object and the judgment I make as to what the corresponding object ought to be. If I have seen a certain arch in Carthage, it is perfectly natural that I should have an idea of it; but the fact that I like the sweep of this arch and consider it beautiful is something that cannot be explained by experience alone. In order to form a judgment as to what things ought to be, our rational mind had to be subject to the action of their ideas,[57] and this, once again, is what is called illumination.”[58]

Avoiding an “ontologistic” interpretation of the Augustinian doctrine of divine illumination (reminiscent of Malebranche and Gioberti in modern times) as presented by thinkers like Ubaghs and Hessen, as well as both the “innate idea” interpretation of it (reminiscent of the rationalist Descartes) and the “agent intellect” interpretation of it (given by Zigliara, Lepidi, Boyer, and Cayré, which would make Augustine’s doctrine essentially the same as Aristotle’s active intellect abstracting from the phantasm),[59] Carmin Mascia, instead, puts forward the following interpretation: “The human soul has the faculty of making judgments, and, in doing so, it affirms that the things perceived are beautiful or ugly, that human actions are good or evil, just or unjust. Making these judgments, we are aware that we do not do so arbitrarily, but we compare the ‘mutable things’ to an absolute and unchangeable norm. There exists, therefore, in ourselves the authoritative standard of an absolute truth, absolute beauty, absolute good. How can we explain the presence of this standard of truth and good? It cannot come from ourselves. For if the truth ‘were equal to our mind,’ truth also would be mutable, ‘since our minds see the truth now more and now less.’ Moreover, we perform many actions which are wrong and evil. The standard that is within us does not come from surrounding things, either, for they are contingent and changing all the time. We know that this is the problem with which Plato was faced and that he resolved the question by admitting an invisible world which is separated from visible things, i.e., the world of Ideas. St. Augustine does not follow Plato in this. He explains the presence of the authoritative standard of beauty, truth and justice on the basis of there being a ‘Teacher’ who suggests them to our soul. This Teacher, who does not speak Greek or Latin, but speaks any language and is understood by everyone, whether free or slave, is God. We know what truth, good and justice mean, because ‘the Word of God’ is teaching us. This relationship of God with the human soul was called by St. Augustine ‘illumination.’ God is the sun of our minds. As our corporeal eyes need the light of the visible sun to see material things, so our soul needs the divine light to see what is absolutely true and good.”[60]

Copleston’s interpretation of the Augustinian doctrine of divine illumination is summed up by him as follows: “St. Augustine asks himself the question, How is it that we attain knowledge of truths which are necessary, immutable and eternal? That we do attain such knowledge is clear to him from experience. We cannot gain such knowledge simply from sense-experience, since corporeal objects are contingent, changeable and temporal. Nor can we produce the truths from our minds, which are also contingent are changeable. Moreover, such truths rule and dominate our minds, impose themselves upon our minds, and they would not do this if they depended on us. It follows that we are enabled to perceive such truths under the action of the Being who alone is necessary, changeless and eternal, God. God is like a sun which illumines our minds or a master who teaches us. At this point the difficulty in interpretation begins. The present writer inclines to the interpretation that, while the content of our concepts of corporeal objects is derived from sense-experience and reflection thereon, the regulative influence of the divine ideas (which means the influence of God) enables man to see the relation of created things to eternal supersensible realities, of which there is no direct vision in this life, and that God’s light enables the mind to discern the elements of necessity, immutability and eternity in that relation between concepts which is expressed in the necessary judgment. Owing, however, to St. Augustine’s use of metaphor and to the fact that he was not primarily interested in giving a systematic and carefully defined ‘scholastic’ account of the process of knowledge, it does not seem possible to obtain a definitive interpretation of his thought which would adequately explain all the statements he made.”[61]    


Saint Thomas Aquinas


Unlike Saint Augustine, the great Dominican philosopher and theologian Saint Thomas Aquinas (1224/5-1274, also known as the “Aquinate” and the “Angelic Doctor”) got much of his doctrine of knowledge from Aristotle, such as the doctrine of abstraction and the process of ideogenesis (the “birth of the idea”) in general. Knowledge, for the Aquinate, consists in the intentional grasping of the forms of things in an immaterial way. The natural form of a thing becomes present in an intentional way (called the intentional species), first as a form particularized (or individualized) in sense knowledge, and later, through abstraction, as a form universalized, first as an impressed species of an intelligible order (the abstracted nature) and ultimately as an expressed species of an intelligible order (the concept). In the process of knowledge, the form individualized is received without matter but with the concrete conditions of matter, and it informs a material power, namely the senses. In the form universalized in intellectual knowledge the form is received without matter and without the concrete conditions of matter, and informs an immaterial power, namely the intellect. Since the essence of the systematic gnoseology presented in the second part of this book is Thomistic and moderate realist in inspiration, instead of repeating ourselves, let us now proceed to the next thinker, the founder of the via moderna, namely, the nominalist William of Ockham.     


The Nominalism of Ockham


The father of nominalism (though his epistemology is somewhat conceptualistic) William of Ockham (1290-1349) affirmed that universals exist only in the mind and do not have any relation to real things. They are but pure concepts. He denied that we could know the real common essences of things. Ockham rejected common natures in things, species, and in general every universal ante rem and in re. He taught that the universal could only be an object of thought, without any metaphysical grounding: “The universal is only in the soul and therefore it is not in things.”[62] For Ockham, there does not exist a common nature in things; essence can be only individual. He writes: “A man can be annihilated by God without any other man being annihilated or destroyed. Therefore, there is nothing in common between them, because otherwise this common element would be annihilated, and no other man would preserve his essential nature.”[63] What principle, then, does Ockham’s nominalist mental and nominal universality ground itself in? Sanguineti explains that “For Ockham the universal is a classification of things, insofar as they are reciprocally similar; Socrates and Plato are more similar to one another than either one of them is similar to a donkey; it is not that Socrates and Plato have something in common: it suffices to say that they are similar to one another according to something. The significative value of the concept is thus reduced to a form of confused knowledge: thinking man, I refer myself confusedly to a quantity of objects, without being able to distinguish the true proper concepts. To conceive Socrates as man is to conceive him in confuse, while to conceive him distinctly is to think of him as Socrates. Consequently Ockham reconsiders the discourse of Scotus on intuitive and abstractive knowledge. Working from his philosophy, the interest now reverses itself onto the intuitive notice, the only one that presents existent reality to us. Abstract knowledge works away from concrete existence; by means of it one cannot know with evidence whether a contingent thing exists or does not exist. On the contrary, the intuitive notice is the apprehension of a thing as existent, an apprehension that allows the formation of a contingent proposition on the existence of things. ‘In general, every simple knowledge of a term or of more terms, of a thing or of more things, in virtue of which one can know with evidence a contingent truth, especially regarding a present fact, is an intuitive knowledge.’[64] The way is cleared to the knowledge of facts by means of experience, which rests at the base of the new scientific direction of modern times.”[65]

Sanguineti, however, does not agree that Ockham’s nominalism can provide a philosophically secure foundation for the experimental sciences: “The new science will not develop itself with only the attestation of facts, but rather with the discovery of causal laws and with the use of mathematics, which is extraneous to the Ockhamist conception. We conclude rather that the nomination of the fourteenth century represents, beginning with the indicated principles, a movement of criticism, revision and finally of general abandonment of the metaphysical certainties of the preceding centuries (rational demonstration of the existence of God, of the immortality of the soul, etc.). Strongly accentuating divine Omnipotence, which can do things different from those that we in reality see, nominalism cancels every form of necessity of the world, leaving it in the hands of the pure contingency of facts. Hence the crisis of philosophy as a science (but also the virtual crisis of every science).”[66]        

What about the famous “Ockham’s razor”? Abstraction, says Ockham, is a fount of error which conjures up hidden and unnecessary entities like essences and substantial forms. Consequently, it is necessary that one eliminate uselessly multiplied abstract entities (Ockham’s razor: non sunt multiplicanda entia sine necessitate). So how do we know? Ockham postulates that we know only what is known intuitively, either by sense intuition or by an intellectual intuition. Centuries later rationalism was to adopt the latter type of intuition (in its direct knowledge of essences) and empiricism the former. Ockham also held the antinomy between faith and reason, which was to become a cardinal tenet of modern philosophy from Cartesian rationalism onwards.










Unlike the phenomenalism of Hume and the transcendental idealism of Kant, the rationalist philosophy of René Descartes (1595-1650) attempted to recuperate an extra-mental reality initially doubted at the outset by his universal methodical doubt. But the tragedy of Cartesian immanentism is that, for Descartes, things are not really intelligible in themselves and in the ultimate account do not really count because what he in the end arrives at is not true reality as it is in itself, but rather a thought-of reality.             

Cartesian Universal Doubt. Descartes doubts our cognitive powers. The senses are not to be trusted. All reality is placed in a state of critical doubt. The first stage of the Cartesian method is the universal methodic doubt: “In order to seek truth, it is necessary once in the course of our life, to doubt, as far as possible, of all things.”[67] “We will also doubt of the other things we have before held as most certain, even of the demonstrations of mathematics, and of their principles which we have hitherto deemed self-evident.”[68]     

From this radical doubt emerges the certainty of the thinking subject. When all has been placed in doubt there remains one thing that cannot be doubted, he says, namely, that I am thinking and that it is by thinking that I exist. Hence the famous line of Descartes: “I think, therefore I am” (cogito, ergo sum). He writes in his Discourse on Method: “I noticed that whilst I thus wished to think all things false, it was absolutely essential that the ‘I’ who thought this should be somewhat, and remarking that this truth ‘I think, therefore I am’ was so certain and so assured that all the most extravagant suppositions brought forward by the sceptics were incapable of shaking it, I came to the conclusion that I could receive it without scruple as the first principle of the philosophy for which I was seeking.”[69] “While we thus reject all of which we can entertain the smallest doubt, and even imagine that it is false, we easily indeed suppose that there is neither God, nor sky, nor bodies, and that we ourselves have neither hands nor feet, nor, finally, a body; but we cannot in the same way suppose that we are not while we doubt of the truth of these things; for there is a repugnance in conceiving that what thinks does not exist at the very moment when it thinks. Accordingly, the knowledge, ‘I think, therefore, I am,’ is the first and most certain that occurs to one who philosophizes orderly.”[70] This is, undoubtedly, immanentism’s making human thought prior to real being. The Cartesian first principle is not a syllogistic conclusion, a product of a demonstrative process; rather, it is an immediate intuition of fact. By intuition Descartes understands “not the fluctuating testimony of the senses, nor the misleading judgment that proceeds from the blundering construction of the imagination, but the conception which an unclouded and attentive mind gives us so readily and distinctly that we are wholly freed from doubt about that which we understand, or, what comes to the same thing, intuition is the undoubting conception of an unclouded and attentive mind, and springs from the light of reason alone.”[71] 

Descartes’ universal methodic doubt endeavors to make us doubt of all things: the whole of the corporeal world, our own body, our sense-perceptions, our internal states of consciousness, the very trustworthiness of our knowing powers (both of sense knowing and intellectual knowing), the first principles of reality such as the principle of non-contradiction and causality, and the very laws of thought founded upon these objective first principles. It is a real, genuine, not simulated (or faked), doubt, as he himself relates: “As I desired to give my attention solely to the search after truth, I thought…that I ought to reject as absolutely false all in regard to which I could suppose the least ground for doubt, in order to ascertain whether after that there remained aught in my belief that was wholly indubitable.”[72] Note the words “to reject as absolutely false” which refers not just to a suspension of judgment but to a conviction that he must reject them as absolutely false, rejecting everything until he reaches the one indubitable fact: “Cogito, ergo sum. Bittle observes that “This is more than mere doubt, because a doubt presupposes a suspended judgement due to the absence of all reasons for and against a proposition (negative doubt) or reasons of more or less equal value for and against it (positive doubt). Descartes ‘supposes for a time, that all these opinions are entirely false and imaginary,’[73] and he ‘will continue always in this track until he shall find something that is certain, or at least, if he can do nothing more, until he shall know with certainty that there is nothing certain.’[74] He assumes the attitude that all spontaneous convictions and laws of thought are errors.”[75] 

From the first certainty (cogito, ergo sum) one obtains further certainties. He deduces the existence of God from his idea of Him (an illicit transfer from the logical order to the ontological order or order of reality). He arrives at the fact that God, being infinite veracity, cannot deceive, and thus, He could only have given man trustworthy sense and intellectual knowing faculties. Having proven in this manner that man’s knowing powers are trustworthy, man can now engage in the acquisition of true and valid knowledge. 

Inconsistencies and Errors of the Cartesian Method. There are many glaring inconsistencies and errors in the Cartesian method. Is Descartes’ universal doubt in fact possible? No, for there are certain gnoseological points which are indubitable, from which we cannot escape even if we are determined to doubt everything: “Anyone who affirms that absolutely everything must be doubted is already making a judgment – which represents his own thesis – and which, therefore, is an exception to what he is affirming: since if everything is to be doubted, nothing can be affirmed, not even the thesis which maintains that everything must be doubted. Nor can one have recourse to maintaining the thesis as merely probable, because even probability has to have some sort of foundation in certainty. And, it is meaningless to affirm that it is doubtful that everything is doubtful, since this affirmation, and all others which are added to it in indefinite regress in order to increase doubt, simply become so many more exceptions to the universality of doubt. He who says he is in doubt already knows something: he knows that he doubts; if he did not know it, how could he possibly affirm it? The awareness of doubt is itself certain knowledge.”[76]  

Descartes attempts to prove the trustworthiness of our sense and reasoning powers by this path: the universal doubt, the first certainty (cogito, ergo sum), the existence and infinite perfection of God departing from the innate idea of Him, God’s absolute veracity, man’s creation by God, God’s veracity as the guarantor of the trustworthiness of the faculties of human knowing, and finally, the truth and validity of all the spontaneous convictions of man’s mind which are ‘clear and distinct.’ What is the problem with this procedure? He presupposes the validity of his reasoning powers and the first principles, such as the principles of non-contradiction and causality, in his demonstrations of God’s existence, before he has proven their trustworthiness, as he has cast them all in doubt in the first place at the beginning with his universal doubt. The Cartesian method assumes beforehand what it intends to prove afterwards. Bittle writes: “When he (Descartes) proposed to approach the problem in an attitude of universal real doubt, discarding even the capability of the human mind to know truth and refusing to accept such essential principles as the principle of non-contradiction and the principle of sufficient reason, he made the solution of the problem impossible for himself. Here are a few considerations which compel us to reject his system: Descartes began his inquiry by doubting all  knowledge without exception; he was even willing to accept it as ‘entirely false.’ But what about the idea of God as an all-perfect Being, since he admits that he discovered this idea in his own mind? According to his own principle of universal doubt, he simply cannot know whether this idea of God is correct or incorrect; as a matter of fact, according to this principle, he should consider it as ‘entirely false,’ until proved otherwise. But if his idea of God as an all-perfect Being may be incorrect, he cannot logically deduce from this idea God’s existence and veracity. Since the very idea of God is doubtful, these other things must remain doubtful, and the trustworthiness of man’s faculties must also remain doubtful. Descartes cannot escape his own real doubt.      

“Irrespective of the intrinsic value of the proofs with which Descartes attempts to demonstrate God’s existence, we must not overlook the fact that he uses a process of reasoning to make this demonstration. Since his very reason and the process of reasoning is as yet of doubtful validity, how can he validly demonstrate God’s existence and veracity? The trustworthiness of Descartes’ reasoning powers is supposed to flow as a necessary consequence from the infinite perfection of God; and God’s infinite perfection is made certain to him by means of a proof developed by these very reasoning powers, before he has proved that these reasoning powers are valid and trustworthy: he thereby gratuitously assumes the very thing beforehand which he intends to prove afterwards. He unconsciously accepts the trustworthiness of his faculties in attempting to demonstrate the existence and infinite perfection of God, and that is an illegitimate procedure; because a doubtfully valid faculty can produce only a doubtfully valid argument, and a doubtfully valid argument can only lead to a doubtfully valid conclusion. The whole argument for God’s existence and veracity is thus nullified by his doubtful reason and reasoning process; and, since he proves the reliability of his reason and reasoning process by means of God’s veracity, which (according to his supposition) must be doubtful, the proof of the trustworthiness of his own powers is nullified and can never be established beyond doubt. His attempt, therefore, to vindicate the validity of human knowledge failed essentially, because, by rejecting the reliability of his own powers to discover and know truth, he made it impossible for himself to extricate himself from the net of his own universal doubt.”[77]

“Descartes,” Bittle observes, “claims to reject everything, even the principle of non-contradiction and the principle of sufficient reason. But he does not. He surreptitiously assumes the truth of these principles and uses them continually. As obvious a fact as the ‘Cogito, ergo sum’ is really based on the validity and truth of the principle of non-contradiction. This principle asserts that it is impossible for something to be and not to be at the same time. Descartes becomes certain of his own existence by the very fact of his ‘thinking’ or ‘doubting.’ True. But why? Because he perceives clearly that it is impossible to ‘think and not think,’ to ‘exist and not exist’ at the same time. If Descartes were consistent and really doubted the principle of non-contradiction, he would have to affirm that it could be possible for a being to ‘think and not think,’ to ‘exist and not exist’ at the same time. But then, according to his own supposition, he could not be sure after all that the ultimate fact of his existence is certain, and his famous ‘Cogito, ergo sum’ has no real objective value. Only by granting the validity and truth of the principle of non-contradiction beforehand, can his existence be established as an objective fact; and that is exactly, though inconsistently, what Descartes does.

“The same line of reasoning applies to his proofs for God’s existence and infinite perfection. Notwithstanding his proofs, his rejection of the principle of non-contradiction will forever invalidate his arguments, because, as long as this principle is not established and accepted, he could never be sure whether it would not be possible for God to ‘exist and not exist,’ to ‘be infinitely perfect and not infinitely perfect’ at the same time. Similarly, he would always be compelled to remain in doubt whether God could not be ‘veracious and not veracious,’ ‘deceiving and not deceiving,’ unless the principle of non-contradiction were taken as granted before he begins to prove God’s existence. Unwittingly Descartes does accept this principle of non-contradiction throughout his demonstrations, but that is an inexcusable inconsistency.

“So too, Descartes conducts his inquiry under the supposition that he has doubted the principle of sufficient reason and the principle of causality. But he does not hesitate to use these principles before he has established their validity. Consider this a posteriori argument for the existence and infinite perfection of God. He contends that the idea of God as an all-perfect Being could not have originated in our mind, because such an idea would exceed the causality of the human mind, the latter being less perfect than the contents of the idea itself; consequently, this idea had to be produced in us by God Himself (and this proves that God exists as an infinitely perfect Being), otherwise there would be no sufficient reason for the presence of such an idea in our mind. This line of reasoning shows plainly that Descartes uses the principles of sufficient reason and causality in demonstrating God’s existence, although he doubts their validity. Now, if he lets these principles stand as doubtful, his entire demonstration is vitiated and nullified by doubt; and if he accepts them as valid prior to establishing their validity, he acts contrary to his fundamental doubt and is inconsistent: in either case he makes the demonstration of God’s existence impossible. His actual procedure in all the arguments he makes is such, however, that he presupposes the validity of these laws of thought; and that is for him a glaring inconsistency, since his universal methodic doubt will not permit him to accept their validity before he has proved the existence and veracity of God. Descartes’ universal methodic doubt leads logically to universal skepticism. No certitude can ever be attained in a system where the very foundations of human reason are completely destroyed. When he rejects as doubtful and even as ‘absolutely false’ all in regard to which he could imagine the least ground for doubt he saws off the very limb upon which he is seated. If the nature of his mind and the laws of thought are called into real doubt (not to speak of considering them to be ‘absolutely false’), then all acts and facts of consciousness, all ideas, judgments and inferences, can no longer be trusted. But how can the mind attempt to validate its own trustworthiness except by means of these things? If Descartes mistrusts the simple judgments ‘2 + 3 = 5’ and ‘A square has four sides,’ how can he trust his faculties in making the far more complicated arguments with which he tries to prove God’s existence and infinite perfections?…Descartes, if he had been consistent, should have embraced universal skepticism, because his universal doubt left him no other choice: he had no way of retracing his course…it is in reality only a variation of universal skepticism.”[78]




The English empiricist John Locke (1632-1704) continued the nominalism initiated by Ockham, as well as the Cartesian immanentist thesis that what we know in the first instance are our representations, but adds to it the specifically empiricist tenet that intellectual knowledge is reduced to sense perception, or at least is in a total function of it. If rationalists like Descartes were above all influenced in their philosophy by mathematics (which is primarily deductive in character), the empiricists were inspired by the experimental sciences like biology and chemistry (which is primarily inductive in character, based on the experience of concrete facts and on experimentation).      

A convinced empiricist, Locke believes that all knowledge has its origin in experience, of which there are two types: sensation and reflection. These latter are, for him, the sole founts of ideas. He rejects Cartesian innatism: there are no innate ideas; man begins his cognitive journey with a blank slate (tabula rasa), which is destined to receive the imprint of simple ideas which come from two sources, namely, sensation and reflection.   

An Essay Concerning Human Understanding. Locke’s theory of knowledge is contained in An Essay Concerning Human Understanding, which is divided into four books: in the first book he criticizes the innate ideas of Descartes; in book two he inquires into the origin of ideas, establishes his system of gnoseological empiricism, and explains his division of concepts into simple ideas and complex ideas; the third book deals with the relationship between words and ideas, while the last book delves into certainty, extension, and the various degrees of knowledge.

Simple and Complex Ideas. “Ideas” are, for Locke, either simple or complex. Simple ideas are those which come through experience and are divided into four classes: 1. those which come to us through one sense (e.g., color); 2. those which come to us through more than one sense (e.g., extension, coming from sight and touch); 3. those which come to us by reflection only (e.g., perception, belief, doubt and volition); and 4. those which are derived from sensation and reflection together (e.g., pleasure, pain, power, existence, unity and succession). Complex ideas, on the other hand, are those which the human mind forms by combining simple ideas derived from experience and are classified into modes (ideas representing that which has no proper and independent existence, and is dependent in being on a substance which it modifies), substances (which, in the logical order, are the mind’s postulate of some subject or substrate underlying and supporting sense qualities; in the ontological order or the order of reality substance is that unknown and unknowable something which supports qualities; man knows that it exists, but does not know what it is), and relations (which are ideas arising from the mind’s perception of an order existing between objects, the chief relation being that of cause and effect).    

Locke’s Confusion of Ideas and Images. Central to Locke’s whole empiricist philosophy is his theory of the idea. For him the idea is the object of our understanding in the first instance (whereas for the realist what is known in the first instance is the extra-mental thing, the object). Locke writes: “Since the mind, in all its thoughts and reasonings, hath no other immediate object but its own ideas, which it alone does or can contemplate, it is evident that our knowledge is only conversant about them. Knowledge, then, seems to me to be nothing but the perception of the connection of and agreement, or disagreement and repugnancy of any of our ideas. In this alone it consists.”[79] This position is, of course, manifestly immanentist: one does not really know extra-mental things objects or noumena but rather ideas or conscious states of the mind. Locke is trapped within the subjectivist prison of his mind.   

Locke again, in the Introduction to his Essay, writes on the idea: “It being that term which, I think, serves best to stand for whatever is the object of the understanding when a man thinks, I have used it to express whatever is meant by phantasm, notion, species, or whatever it is which the mind can be employed about in thinking.”[80] Bittle comments: “In this superficial definition Locke unfortunately lumps together as ‘ideas’ things which might conceivably be radically different in nature, namely ‘phantasm, notion, species, or whatever it is which can be employed about in thinking.’ By thus arbitrarily blurring the nature of the ‘idea’ so as to include the images of sense-perception (‘phantasm, species’), he laid the foundation for sensism, in which all ‘thinking’ is nothing but a form of ‘sensation.’ Descartes placed all sense-perception in the spiritual mind, thus identifying sense-perception with spiritual activity; Locke here does the reverse, by reducing ideas, at least in part, to the level of sense-perception. This confusion of ideas and images is present in all his philosophy.”[81] Further criticizing Lockean empiricist sensism, Bittle writes: “For one thing, Locke simply assumes without proof that ‘ideas’ and ‘images’ are identical. This identification of ideas and images wipes out the distinction between sensory and intellectual knowledge simply by definition. Again, according to his definition of the ‘idea’ the idea is the object of our understanding, instead of the reality of things being the object of our intellectual knowledge. All we can know, then, are ‘ideas,’ internal states of mind; in that case, however, we can acquire no knowledge of the material world as it is in itself. If carried out to its logical conclusion, such a theory must inevitably end in subjective idealism.”[82]




George Berkeley (1685-1753) believed his mission to be the vigorous defense of theism and the affirmation of the primacy of the spirit over matter against the growing materialist trend among British intellectuals. He described his philosophical system as an immaterialism since it is aimed at responding to the errors of materialism. What exactly is immaterialism? Berkeley retains that matter does not exist in itself. When we say that something exists we mean that such a thing is perceived by us, that is, its entire being consists in its being perceived (esse est percipi). The being of things is resolved into thought-of-being. Primary sensible qualities are judged to be merely subjective as they are known through secondary sensible qualities. Thus, bodies are, for Berkeley, nothing but sensible qualities and so one should not suppose that there be some sort of ‘substance’ holding up these qualities. “Their esse consists in their percipi (to be perceived), and it is not possible for them to have any existence outside the minds which perceives them.”[83] We should not suppose a ‘substance’ underlying our ideas of the accidents of bodies since the true support of these ideas is, namely, our very own mind.

For Berkeley, “things exist therefore only as objects of our senses, as phenomena (from the Greek, ‘what appears before me’). It may be that Berkeley did not want to deny the existence of the world of bodies but just to combat materialism by means of the immateriality of knowledge. Nevertheless, by virtue of the principle of immanence, which he follows, he turns the in-itself into a for-myself. There is no matter in itself: it exists only in my consciousness. And my consciousness consists in perceiving ideas (in the Lockean sense) and in perceiving itself intuitively. (…) Kant would dismiss Berkeley’s philosophy as dogmatic idealism.”[84]

Berkeleyan gnoseology dictates that the material world exists only as a cognitive act, produced and existing in a mental act; consequently this world is merely subjective, not objective. For Berkeley, there is no extra-mental world of matter, only spirits (finite spirits and the Infinite Spirit) and ideas and experiences. Finite spirits are capable of forming ideas and experiences of their own (i.e., the idea of a centaur or an elf), but what about the objects that we see, for example, when we gaze at a landscape outside our window, which we are unable to modify or change? Berkeley teaches that these objects are caused by the Infinite Spirit, God, who imparts them to passive finite spirits in their process of knowledge. The passivity of our finite spirit, says Berkeley, is, in fact, a proof of the existence of the Infinite Spirit, who causes the ideas imposed on one’s finite spirit of which one is not the origin (i.e., the various objects that we see when we look outside our window, like the trees, mountains, clouds, etc.). “While denying the existence of a material world and reducing it to a phenomenon of knowledge,” explains Mascia, “Berkeley believed that he had proved the existence of the subjective spirit from the very presence of ideas, for ideas can be produced only by a spirit. Having thus assured himself of the existence of his own spirit, Berkeley devoted himself to determining its nature: the spirit is both active, a producer of ideas, and passive, a receptacle for ideas. Its activity is revealed in the imagination and in the memory, with which we produce or recall ideas, but more still in the coordination of ideas. Passivity, as we have said, is revealed in the fact that the spirit receives ideas that it has not produced. For example, it is not within my power to see or not to see the objects that are in my room. The passivity of the spirit gave Berkeley the means of proving the existence of other finite spirits, independent of his own, and the existence of God. In fact, he asked, what is the origin of these ideas that are imposed on my spirit and of which I am not the origin – for instance, the objects I mentioned before as being present in my room? They are produced by the will of other spirits, since I perceive, besides my own spirit, other particular agents like myself, who participate with me in the production of many ideas. Besides, there are ideas that I perceive which are not only not produced by my spirit, but are not produced by any finite spirit – for instance, the regularity of natural phenomena. Fire always burns, independently of any will. Such ideas presuppose a cause superior to all finite spirits – God, who exists, whose infinite will produces the order and harmony and constancy of natural phenomena.

“Having thus demonstrated the existence of God, Berkeley believed that he had solved all the difficulties that could be raised against his idealistic phenomenalism. If, for example, one asks whether the objects in my room exist when I am outside and there is no one in my house, Berkeley answers in the affirmative; because if the objects are not perceived by a finite spirit they are perceived by God. If one should inquire about the difference between real fire and painted fire, why one burns and the other does not, Berkeley would have answered that God, the producer and supreme ruler of all ideas, unites to the first (real fire) the idea of burning, and denies it to the second (fire depicted in a painting). In a word, the phenomenal world of Berkeley is not unlike the phenomenal world that everyone knows, with this difference: While commonly it is believed that natural phenomena are the product of a physical, material world, for Berkeley this material world does not exist. That which we attribute to matter, he says, must be referred to God, the exciter and revealer of ideas corresponding to material things. We are on the ground of the occasionalism of Malebranche: God presents to our souls – produces in them – the ideas that impress us. The constant relationship with which God determines the ideas of our spirits are the so-called laws of nature. They are the language with which God reveals Himself and speaks to us. Thus Berkeley believed that he had carried out the work he had set for himself: to justify theism against the attacks of incredulity; and to point out the emptiness of materialism by proving that the world as conceived by the materialist does not exist.”[85]  




With the empiricist gnoseology of David Hume (1711-1776) we find human knowledge restricted to the level of the senses. For Hume, all man’s knowledge consists of perceptions, which can either be strong (impressions) or weak (“ideas”).[86] All these impressions and ideas have their origin in sense experience. Impressions, for him, are very vivid and immediate, the first products of the mind. Ideas, on the other hand, would be of a derivative and inferred character, mere reproductions or copies of those original impressions or elaborations of them, and can be manipulated and ordered among themselves by the imagination, according to the “law of association” (resemblance, contiguity in time and place, and causality). These laws of association of ideas are purely psychological laws.

For Hume there are no universal concepts, only general ideas, “ideas” being simply blurred images expressing a resemblance common to a collection of particular sense perceptions. Therefore, all the contents of our experience must be particular and contingent, the consequence being that we would be unable to have a basis at all for any universal and necessary knowledge.

The core of Humean empiricist epistemology is that what we know are our perceptions, not external, extra-mental reality. What the human mind knows is not something existing outside consciousness, but merely facts of consciousness. What is known are not real things but only our perceptions which are subjective modifications produced in us by sensible experience. Hume writes: “Now since nothing is ever present to the mind but perceptions, and since all ideas are derived from something antecedently present to the mind, it follows that it is impossible for us so much as to conceive or form an idea of anything specifically different from ideas and impressions. Let us fix our attention out of ourselves as much as possible; let us chase our imagination to the heavens, or to the utmost limits of the universe; we never really advance a step beyond ourselves, nor can we conceive any kind of existence, but those perceptions which have appeared in that narrow compass. This is the universe of the imagination, nor have we any idea but what is there produced.”[87]

Then comes the attack on the objective validity of the principle of causality[88]: Hume denies the objective, universal and necessary validity of this principle. It is simply not objectively, universally, and necessarily true, he argues, that every effect has a cause, since in human perception cause and effect are in fact two phenomena with two separate existences, one following after the other. We cannot therefore conclude that the latter phenomena is due to the causality of the former just because it comes after it. The only conclusion that we can come up with is that, owing to the laws of the association of ideas,[89] it is believed (felt) that a certain phenomenon is caused by another, because, by habit, we have grown accustomed to believe it. For him, causality does not truly occur in extra-mental reality but is rather a subjective phenomenal complex idea, a creation of the human mind. With this doctrine Hume dismisses the traditional a posteriori demonstrations of the existence of God as being devoid of demonstrative capacity.[90]    

So, in Hume’s system we simply do not have a perception of a cause. All that is perceived, experienced, are successive sensations. There is no intrinsic connection between these sensations nor any necessity for such a connection. So, what is this principle of causality that the scholastics boast about? Simply a subjective product of habit. We have gotten so used to seeing fire burn that, by habit, we say that fire causes the burning; but since Hume states that we cannot sense this causing, this causing can be but a subjective product of the imagination.

There is nothing we can know beyond our sense perceptions, says Hume, whether noumena in the world or God. All we can do is believe as our imagination fancies. We are unable to prove the existence of God by means of the metaphysical principle of causality for causality has no objective value. With the empiricist doctrine of the inability of the mind to ascend from the level of experience to the establishment of the existence of a cause that exists and operates on a level of reality above the level of the senses, Hume has wiped out (from his own skeptical mind) metaphysics and, with it, philosophy of God, the highest branch of metaphysics. For Hume, one cannot rationally demonstrate the existence of God for there is no power of insight and understanding in man different in kind from the bodily senses. Such is Humean skeptical empiricist agnosticism.

How then does he explain the fact that so many people have a notion of a Supreme Being, whom they do not hesitate to call God? His answer: that too is a product of the imagination, something concocted out of many varied sense impressions. He does not deny its psychological value and use, as does the psychological utility of many of our other products of the imagination. But the simple fact is that the real existence or non-existence of God is outside the mind’s power to know.

Hume did not want to be branded an atheist and, at times, admitted religion’s utility and practical value for society. Nevertheless, his writings reveal his philosophical views that describes supernatural Christian religion as nothing but a creation of man’s fertile imagination, and that even a deistic “illuminist” religion founded on the rational metaphysical principles of philosophy of God had no experiential or rational foundation. All religions are of equal value for they all lack any empirical basis. Religious beliefs and their habits of association are explained through instinct and in the habits of association which arise from it. A religion may be permitted if it has practical utility: as a source of consolation, altruism, fraternity, etc. Naturally, the permitted religions should be devoid of all unreasonable fictions of the imagination, such as belief in mysteries and miracles; the only useful “religion,” according to Hume, would be a purely earth-bound social work and philanthropy wholly devoid of the supernatural.[91] 

Hume’s skepticism regarding extra-mental reality must also be addressed. Humean philosophy cannot admit that there is anything real, anything objectively existing outside the states of human consciousness. The verdict of Hume’s radical empiricism is that the real existence of things can be but a hypothesis incapable of verification, a postulate that can neither be proved nor disproved. Now, contrary to Hume’s radical empiricism, the existence of things is not an hypothesis or a postulate, that is, something that we must assume since we cannot prove it, but, rather, an evident fact. An hypothesis or assumption is something that we cannot, at the moment, prove or disprove; for example, that the cure for cancer will be discovered in 2089. One can assume that the cure for cancer will be discovered at that point in time, but we simply cannot prove it. We can neither prove that it will not occur at that point in time. But if the cure for cancer is discovered in 2095, then we are no longer dealing with an assumption but with an accomplished fact. Now the existence of things in the world that we see around us is not an hypothesis but a fact. They are not assumed but given. Naturally, the existence of the things of the world cannot be proved because they need no proof; they are self-evident. We start with the things of the world; we say that these things are, for these things are there to begin with. They are thus judged to exist for they simply do exist.  

Hume’s main problem lies with his reduction of human knowledge to the level of the senses, thus denying that man has the power of abstraction. For Hume, sense experience was the ultimate source of valid human knowledge. Thrown out together with metaphysics are substance and causality. Having done this he remained agnostic concerning God’s existence, a natural consequence of his sensism. Criticizing Hume’s radical empiricism, Celestine Bittle notes a number of things: “First, Hume’s explanation of ideas as faint images of sense-impressions is totally inadequate. Since both are of a sensory character, they are concrete and individualized. Our ideas, however, are abstract and universal. There is, as we have shown, a radical difference between ‘sensations’ and ‘images’ on the one hand and ‘intellectual ideas’ on the other. To ignore or deny these differences is a serious error. Second, Hume’s explanation of universal ideas is totally inadequate.[92] The process of forming universal ideas is not at all the way Hume pictures it. We acquire them by a process of abstraction, taking the objective features common to a number of individuals and then generalizing the resultant idea so that it applies to the whole class and to every member of the class. It is not a question of merely labeling objects with a common name. Intellectual insight into the nature of these objective features, not ‘custom’ or habit, enables us to group them together into a class. Third, Hume’s explanation of the origin and nature of the necessarily and universally true axioms and principles, such as the principle of causality and the principle of non-contradiction, is totally inadequate. He explains their necessity and universality through association. Now, the laws of association are purely subjective laws with a purely subjective result. Consequently, the ‘necessity’ which we experience relative to the logical connection between subject and predicate in these principles would not be due to anything coming from the reality represented in these judgments, but solely to the associative force existing in the mind. It is a subjective and psychological, not an objective and ontological, necessity. The mind does not judge these principles to be true because it sees they cannot be otherwise; it cannot see them to be otherwise because the mind in its present constitution must judge them to be true. So far as objective reality is concerned, 2 + 2 might equal 3 or 5 or any other number; and there might be a cause without an effect, or an effect without a cause. If Hume’s contention were correct, that our observation of ‘invariable sequence’ is the reason for assuming an antecedent event to be the ‘cause’ of the subsequent event, then we should perforce experience the same psychological necessity of judgment in all cases where we notice an invariable sequence in successive events. Experience, however, contradicts this view. For instance, day follows night in an invariable sequence; but nobody would dream of asserting that the night is the ‘cause’ of the day. In an automobile factory one car follows the other on the belt line in invariable sequence; but this association does not compel us to think that the preceding car is the ‘cause’ of the one following. Reversely, when an explosion occurs but once in our experience, we search for the ‘cause’ of this ‘effect’ and are convinced there must be a cause present; here, however, there can be no question of an ‘invariable sequence’ of events. Fourth, Hume’s theory, if accepted as true, must destroy all scientific knowledge. The very foundation of science lies in the principles of non-contradiction, sufficient reason, and causality. If these principles are valid only for our mind and do not apply with inviolable necessity to physical objects in nature, the scientist has no means of knowing whether his conclusions are objectively valid. His knowledge is nothing but a purely mental construction which may or may not agree with extra-mental reality. But science treats of physical systems and their operations, not of mental constructions. Since, according to Hume, we can know nothing but our internal states of consciousness, we could never discover whether the external world and other minds exist at all; driven to its logical conclusions, such a theory can end only in solipsism or in skepticism.”[93]




The Critique of Pure Reason. In his Critique of Pure Reason, the German transcendental idealist philosopher Immanuel Kant (1724-1804) sought out the value of the human sciences, especially that of metaphysics. In order to do so he believed that it was necessary to inquire into the origins of scientific knowledge, searching the reason why such knowledge is formed in us. The point of departure of his inquiry would be the scientific judgments of mathematics, physics, and first principles such as the principle of causality, foundation of scientific knowledge. He asks: How are such universal and necessary judgments possible? There were two historical solutions: the first was the rationalist claim that science has a totally a priori origin in us through a pure analysis of one or more primitive concepts. Such scientific judgments were called analytic judgments. The second solution was the empiricist claim that science has its absolute origin from sensible experience through a posteriori synthetic judgments. But Kant was unconvinced by these explanations since he observed that scientific judgments had the following essential characteristics: universality-necessity and increment of new knowledge. In the case of the rationalist claim, yes, universality and necessity were explained but not increment of new knowledge. As to the empiricist claim, yes, increment of new knowledge was explained but not universality and necessity since all that comes from sense experience can only be particular and contingent. What was needed was a union between the necessity and universality of the analytic judgments of the rationalists and the increase of new knowledge provided by the synthetic a posteriori judgments of the empiricists. So, Kant’s solution was that man obtains scientific knowledge through synthetic a priori judgments. Scientific judgments have their origin by way of synthesis between something caused in us by something external to us and subjective elements which the mind possesses by force of its very constitution. He believed that the ultimate root of the errors of the rationalists and the empiricists was the erroneous concept of human knowledge. The rationalists claimed that all knowledge comes from the subject, while the empiricists held that all knowledge is derived from the object. Because of these errors, Kant claimed that scientific knowledge would be impossible because the object would only supply an increment of new knowledge and the subject would give only universality-necessity. Knowledge, for him, is not the fruit of the subject solely or of the object solely, but rather, it is a synthesis of the combined action of subject and object: the subject procures the form and the object the matter. Knowledge would be the result of an a priori element (the subject) and an a posteriori element (the object). The resulting judgments would not just be only analytic or only synthetic but would be synthetic a priori. Synthetic a priori judgments would be a sufficient guarantee for the validity of the sciences which acquires increment of new knowledge from the object and universality-necessity from the subject.   

This new relationship between subject and object in the knowing process is Kant’s Copernican Revolution. Realism claims that man can really know extra-mental things, obtaining immaterial ideas (which are universal) by abstraction from sense experience. It believes that it is the mind that revolves around things in the extra-mental universe. Truth would mean the conformity (adequation) of our minds or judgments to real things. Kant rejects this realism as illusory and ingenuous. His claim is that it is not the mind that revolves around the thing but rather the thing that revolves around the mind. “It has hitherto been assumed that our cognition must conform to the objects; but all attempts to ascertain anything about these objects a priori, by means of conceptions, and thus to extend the range of our knowledge, have been rendered abortive by this assumption. Let us then make the experiment whether we may not be more successful in metaphysics, if we assume that the objects must conform to our cognition. This appears, at all events, to accord better with the possibility of our gaining the end we have in view, that is to say, of arriving at the cognition of objects a priori, of determining something with respect to these objects, before they are given to us.”[94] “According to Kant, it is the intellect which imposes its conditions upon sense phenomena and not vice versa. This is precisely the Copernican revolution which Kant carried out: instead of the subject attending to objects, it is the objects which depend on the thinking ego. In broader terms, we are facing a transfer of the foundation from being to thought: now it is thought which founds being…For Kant, nature is no more than a set of formalized phenomena whose laws are not given by the structure of things as they are in themselves, but rather are prescribed to nature by the intellect. It is we, says Kant, who introduce order and regularity into natural phenomena, and we would not be able to discover this order and regularity if it had not originally been placed there by the nature of our minds.”[95]   

To answer the basic question, “What can I know with scientific certitude?,” Kant wrote The Critique of Pure Reason. In this work he examines in a critical way the very structure of human reason, assigning to man a threefold knowing power: sensibility, intellect and reason. Out of the threefold knowing power of man arises, respectively, the three parts of the Critique: the transcendental esthetic, the transcendental analytic, and the transcendental dialectic.

The Transcendental Esthetic. Kant calls “transcendental” every knowledge that has something to do with the way the human mind knows objects. “Transcendent” is that which goes beyond all experience. The transcendental esthetic’s scope is to examine how mathematics and geometry are possible. He retains that these sciences are possible because the mind is endowed with two a priori forms that have the characteristics of universality and intuitivity: space and time. Space and time are not, for him, extra-mental realities but a priori forms of the human mind.[96] Kant writes: “In a phenomenon I call that which corresponds to the sensation its matter; but that which causes the manifold matter of the phenomenon to be perceived as arranged in a certain order, I call its form. Now it is clear that it cannot be sensation again through which sensations are arranged and placed in certain forms. The matter only for all phenomena is given us a posteriori; but their form must be ready for them in the mind (Gemüth) a priori, and must therefore be capable of being considered as separate from all sensations…In the course of this investigation it will appear that there are, as principles of a priori knowledge, two pure forms of sensuous intuition (Anschauung), namely, space and time.”[97] Bittle observes that “bearing in mind Kant’s axiom that nothing necessary and universal can be derived from experience, but must proceed exclusively and a priori from the mind itself, Kant finds that sense-perception contains a double element: the ‘manifold’ of sense impressions, which is derived from experience, and ‘space’ and ‘time,’ which are pure forms of the mind. External to the mind there exists a world of things-in-themselves (Dinge-an-sich) or noumena; they are real physical beings. These make impressions on the sense-faculty, and the faculty responds with an ‘intuition’ or perception. These impressions are unarranged, chaotic. This chaotic ‘manifold’ must be arranged in a certain order, and this is done by means of the two sense forms ‘space’ and ‘time.’ Space and time are in no way attributes of the things-in-themselves,[98] but merely ‘cause the manifold matter of the phenomenon to be perceived as arranged in a certain order,’ i.e., as arranged in the order of ‘space’ or in the order of ‘time.’ Since all intuitions or perceptions appear as arranged in a spatial and temporal order, ‘space’ and ‘time’ are universal and necessary conditions of sense-perception and as such must exist a priori in the mind. They are like mental molds into which the unarranged raw materials of sense are poured, so that, after the molding process of cognition is completed, all phenomena appear arranged and molded in ‘space’ and ‘time.’ The objects themselves are, so far as we know spaceless and timeless.”[99]  

In the transcendental esthetic, Llano observes that Kant “develops a theory of sensation and of the phenomena of experience understood as the indeterminate object of an empirical intuition. The matter of the phenomenon is sensation, the subjective reaction of consciousness to having the senses affected. The matter of phenomena is given to us a posteriori since it comes from exterior reality, whose existence Kant must admit, in some way, as the origin of the empirical data passively received by our senses. The primal characteristic of empirical data is their multiplicity, because they come from multiple stimuli. In contrast, the forms of phenomena – space and time – are the unifying and ordering structures of empirical intuitions. Space and time are conditions for the possibility of empirical phenomena. These a priori or pure forms are imposed upon phenomena by the nature of our senses: space is the form of the intuitions of the external senses and time is the form of the intuitions of the internal senses. As forms of all phenomena, space and time are universal and necessary; thus scientific (synthetic a priori) judgments are possible in geometry (constructed upon the pure spatial form) and in arithmetic (built upon pure temporal structures).”[100]

The only form of intuition that man is endowed with is sensible intuition. Thus the mind can reach only phenomena (things which appear to us) and not noumena (things-in-themselves). We only know things as they appear to the human mind and not extra-mental reality as it is in itself. In The Critique of Pure Reason and in the Prolegomena to any Future Metaphysics Kant affirms the existence of noumena (things-in-themselves) that are the cause of the phenomena, but as to what noumena are in themselves, we simply do not know.[101] Bittle explains Kantian noumenal agnosticism, writing: “Do we really perceive external objects, so that the objects of sense actually exist, as we perceive them, outside our person? We do not. The real objects of the physical world can never be perceived; we know absolutely nothing about the noumena or things-in-themselves:‘All our intuition is nothing but the representation of phenomena…Nothing which is seen in space is a thing-in-itself, nor space a form of things supposed to belong to them by themselves, but objects by themselves are not known by us at all, and that what we call external objects are nothing but representations of our senses (phenomena).’[102] All we can know, then, are phenomena or appearances, and these are always subjective in character, without any resemblance to the things-in-themselves. Even man’s perception of his own body is thus seen to be only ‘phenomenal’; whether any extra-mental reality corresponds to what he perceives to be his ‘body,’ man can never know. Kant admits the existence of things-in-themselves as the exciting cause of sense-perception on the grounds of inference; but they remain an unknown and unknowable X…Since all our knowledge in sense-perception is limited to intra-subjective phenomena, he is a transcendental idealist. He failed to overcome the Cartesian antithesis between mind and matter; the mind remains imprisoned in its conscious states and can know nothing of the external world and non-ego objects.”[103]         

The Transcendental Analytic. Just as phenomena stir the sensibility to act, so the finished products of sensation stir the next knowing power, the intellect, to act. The intellect takes in these finished products of sensation which are empirical intuitions and conforms them to its shape, its inborn a priori forms. These forms are four sets of triple judgments called the twelve categories. These categories are like molds into which the molten metal of empirical intuitions is poured, and the resulting piece of knowledge is, in each case, a judgment. The four master categories (each of which has three branches) are: quantity, quality, relation, and modality. Thus the judgment “A comes from B as effect from cause” is not the objective knowing by the human mind of a state of fact, as it is in realism, but rather, it is merely the result of the action of the intellect putting the empirical intuitions of A and B through the mold or category of relation, and through that branch of relation called cause-effect. Causality is not, for Kant, something that occurs in extra-mental reality between things but is rather subjective and immanent to human consciousness.    

The Transcendental Dialectic. In this final part of The Critique of Pure Reason Kant studies the function of “reason” (reason in the sense of the faculty that researches the unconditioned) in order to determine the possibility of metaphysics. The “ideas” of reason are: soul (the unconditioned which lies at the foundation of psychical phenomena), world or cosmos (the unconditioned that lies at the foundation of physical phenomena), and God (the unconditioned that lies at the foundation of all reality). Kant retains that metaphysics arises from a legitimate exigency but sustains that it is impossible for us to demonstrate the objective noumenal value of the ideas of reason. The idea of soul is the result of paralogisms, the idea of cosmos or world falls into antinomies, and the idea of God is founded upon three “proofs” (ultimately reducible to the ontological argument) that are all invalid. The ideas of reason, therefore, have only a regulative use (they indicate a point of problematic convergence) and not a constitutive use (they don’t represent objects to us). Regarding the existence of God Kant was an agnostic, a logical consequence of his transcendental idealist gnoseological immanentism where one is trapped in appearances within human consciousness and incapable of transcending to extra-mental reality and knowing things-in-themselves.  

A Critique of Kant’s Transcendental Idealism. Kant’s philosophical system is plagued with numerous contradictions and errors. For one thing, he affirmed the existence of the noumenon but added that it was impossible to know anything about it. But if we know that it exists then Kant’s claim that we know nothing of the thing-in-itself (noumenon) is not true. He also claimed that the noumenal world is a chaotic mass. It is the mind that eventually structures the object and not the mind conforming to the laws of extra-mental reality. But how can we know that the noumenal world is a chaotic mass since the Kantian claim is that we can know nothing of the thing-in-itself (the noumenon)? Again, he is inconsistent.

Kant goes to great efforts to analyze and describe the intellect and its operations. He appears to know the intellect and its functions extremely well. But isn’t that analyzing and describing a noumenal reality, a thing-in-itself? If the noumenon is totally unknowable then the intellect and its operations would be unknowable. The intellect and its operations are not phenomena for they are not the objects of sense experience. We cannot see and touch human reason. Again, his system breaks down.

Kant claimed that existing extra-mental things-in-themselves (noumena) are the causes of the phenomena that appear to us. Phenomena would be effects of their causes which are noumena.[104] In the Prolegomena we read that things-in-themselves are unknowable as they are in themselves but that “we know them through the representations which their influence on our sensibility procures for us.”[105] But this is making use of the objective metaphysical principle of causality and acknowledging causality in the extra-mental world. This is a plain violation of his philosophical system that claims that causality is not something of the extra-mental real world but rather something rooted in the very structure of the human mind as a category.[106] In order to rectify this blatant error Kant revised his doctrine on the noumenon in the second edition of The Critique of Pure Reason which came out in 1787.[107] His second new doctrine claimed that the noumenon should not be thought of as an extra-mental thing existing in reality but merely as a limiting concept.[108] In its negative sense, which should be adopted, the noumenon is that which is not the object of sense intuition.[109] What does he do here? He denies the objectivity of the thing-in-itself thus correcting his own violation of his own principle of causality immanent to the human mind.[110] But though he gives us a new doctrine on the noumenon, even now affirming that we do not know if it exists or not, there are still many parts of his work in his critical period that clearly affirm the existence of noumena and their being the causes of phenomena, as B 34 of the second edition of The Critique of Pure Reason and Prologue 13, remark 2 of the Prolegomena attest to. Kant could not, even with his new doctrine of the noumenon, free himself from contradictions in his philosophical system.           

It is not true, as Kant claims, that man is endowed only with sense intuition. We are endowed with intellectual intuition as for example when we know ourselves. And to think that the knowledge of mathematics and geometry is due solely to sense intuition is absurd.

Bittle lists a number of other problems with Kantian idealism: “Kant’s theory is contrary to the science of psychology. He maintains that ‘space’ and ‘time’ are subjective ‘forms’ of the mind, given prior to all experience. The findings of psychology are definitely opposed to this claim. Sensory experience contributes its share to our perception of ‘space’ and ‘time,’ as experimental psychology has definitively established. We acquire our knowledge of space and time from a perception of objects which are larger or smaller and which are at rest or in motion. Persons suffering from a congenital cataract have no antecedent knowledge of visual space; after a successful operation, they must acquire knowledge of space through experience and perception. If the subjective mental form of ‘space’ were, as Kant claims, a necessary condition for perception, making the perception of phenomena possible, then there seems to be no valid reason why the mind cannot impose the form of ‘visual space’ upon the incoming impressions, even though a person be congenitally blind. The evidence, however, points clearly to the fact that the knowledge of space on the part of the mind is conditioned by the perception of objects, and not that the perception of space is conditioned by some a priori form present in the mind antecedent to experience. But if ‘space’ is an attribute of bodies, then so is ‘time,’ because both are on a par in this respect.”[111]   

“Kant’s theory is contrary to the fundamental principles of the physical sciences. Kant evolved his theory for the expressed purpose of revindicating scientific knowledge and freeing it from the bane of Hume’s skepticism. He failed. Science treats of the physical objects of the extra-mental world and not of mental constructions; Kant’s world, however, is a world of phenomena, and these phenomena are mental constructions which give us no insight whatever into the nature and reality of things as they are in themselves. According to Kant’s conclusions, the physical, noumenal world is unknown and unknowable. Science is convinced that it contacts and knows real things outside the mind. Science is based on the objective validity of the principle of cause and effect operating between physical objects and physical agencies; according to Kant, this principle is an empty a priori form merely regulating our judgments and applying only to phenomena. The laws which science establishes are considered by scientists to be real laws operating in physical bodies independent of our thinking; according to Kant, these laws merely relate to phenomena within the mind and not to nature at all. Kant states: ‘It sounds no doubt very strange and absurd that nature should have to conform to our subjective ground of apperception, nay, be dependent on it, with respect to her laws. But if we consider that what we call nature is nothing but a whole (Inbegriff) of phenomena, not a thing by itself, we shall no longer be surprised.’[112] We are indeed surprised that Kant would accept this conclusion of this theory rather than see therein the utter fallaciousness of the theory itself which could consistently lead to such a ‘very strange and absurd’ conclusion. That such a conclusion destroys the validity of science in its very foundations, must be obvious.”[113]

“Kant’s theory destroys the foundation of all intellectual knowledge. Ideas and judgments are supposed to reflect and represent reality; they are supposed to tell us ‘what things are.’ Truth and error reside in the judgment. In forming judgments we first understand the contents of ideas and then have an intellectual insight into the relation existing between the subject-idea and the predicate-idea. According to Kant, we do not make judgments because we perceive the objective relation of the subject-idea and the predicate-idea, but because a blind, subjectively necessitating law of our mental constitution draws certain sense-intuitions under certain intellectually empty categories prior to our thinking, and we do not know why these particular categories, rather than others, were imposed by the mind on these sense-intuitions. Our ‘knowledge’ is as blind as the law that produces it. Intellectual knowledge is thus utterly valueless, because it gives us no insight into the nature of the reality our ideas and judgments are supposed to represent.”[114]

Kant claimed that nothing universal can come from experience. This is false since the universal can come from experience by way of the realist doctrine of abstraction.








Absolute Idealism


Adopting the principle of immanence as an a priori given, idealism maintains that all things, either partially (Kantian) or totally (absolute idealism), are immanent to thought, to the consciousness of the thinking subject. While Kantian transcendental idealism admits that there exists something independent of consciousness (partial idealism) German absolute idealism (Fichte, Schelling, and Hegel) arrives, instead, at the total identity between thought and reality, negating the Kantian noumenon (or thing-in-itself); being would belong fully to thought, the latter positing the former in existence.

The Surpassing of the Kantian Thing-in-Itself. Kantian transcendental idealism did not sustain that the human subject created reality, the thing-in-itself; rather, it held that the subject was the creator of the supreme conditions of reality, namely, the forms and transcendental categories that, united with the raw sense data caused by the extra-mental thing-in-itself, produced the phenomenon (the product of both subject and object). The absolute idealists rejected the existence of the Kantian extra-mental thing-in-itself as contradictory for they argued that the philosopher of Königsberg commited a grave error in utilizing the principle of causality, which was valid only for phenomena, to the level of the thing-in-itself as cause of the raw sense data that, molded with the a priori forms of sensible intuition (space and time), formed the matter of knowledge. For the German idealists like Fichte, Schelling, and Hegel, it was but natural to conclude to the position of absolute idealism. They simply negated the illicit application of causality to the level of the noumena and centered on the Ego as the supreme ordering and unifying activity of both external and internal experience. There was no need for the thing-in-itself. It did not exist, for the all-unifying Ego was the supreme creator of reality itself. The Ego was not anymore limited by the sensible contents of the mind or by the supra-sensible noumenical universe. One must turn solely to the Ego as the creator, not only of forms, but also of the content of experience and not be dependent upon any extra-mental noumenal foundation. Thought is the supreme principle of reality itself; any limit to thought can only be posited by thought itself. Likewise, this limit can only be surpassed by thought itself. Absolute idealism believed that thought is reality, that thought creates reality, that thought is not only the condition of being but creates being itself. Though Fichte, Schelling, and Hegel all sustained that thought creates reality, they developed their absolute idealisms in different ways: Fichte developed his in an ethical way, Schelling in an aesthetical way, and Hegel in a logical way. Though they all sought to the surpass the Kantian thing-in-itself, they nevertheless were especially indebted to Kant for the development of their philosophies: The Critique of Practical Reason (which addresses the problem of ethics, action and duty) profoundly affected Fichte, the Critique of Judgment (dealing with sentiment and art) inspired Schelling to pen his aesthetic, absolute idealist system, and the Critique of Pure Reason (dealing with the problem of knowing) greatly influenced the master gnostic and panlogician Hegel.                             




Johann Gottlieb Fichte’s (1762-1814) philosophy is primarily ethical and practical rather than speculative: the question he asks at the outset is not “What can we know?” but rather “What is the mission of man?” It is only after this initial query that a second question is asked: “What are the essential conditions that make man exist?” Thus, ontology and theory are subordinated to ethics and praxis, which is the opposite of the Aristotelian-Thomistic philosophical hierarchy where moral philosophy is subordinated to, and founded upon, metaphysical principles. The primacy of the ethical and practical in Fichte is also seen in the fact that, for him, the essence of the ego consists in the will (so much so that the practical reason is the root of all other reasons) and that the world (what he calls the non-ego) is not conceived of as an object of contemplation, an object of knowledge, but rather as an obstacle to be surpassed. Man must not contemplate the world; rather, the world is the world of man’s duties, duties above all to one’s Nation.     

As was mentioned, Kantian transcendental idealism presupposed the thing-in-itself (the noumenon), that extra-mental, extra-subjective unknowable that would be the cause of the raw sense data of the senses that would go to be formed by the two a priori forms of sensibility, namely, space and time (which are wholly subjective). Fichte, however, believed that the Kantian noumenal reality limited and conditioned the activity of the transcendental ego and proposed that in order for the ego to be truly free one must eliminate that “useless appendix,” namely, the noumenon. For Fichte, ego is everything, so where does this extra-subjective noumenal unknowable fit in? It doesn’t fit in anywhere since idealism dictates that that which cannot be known doesn’t exist. Therefore, the noumenon does not exist. This is the verdict of Fichtean absolute idealism. For Fichte, ego is all, it being the infinite and the finite at the same time. The ego is infinite because it is ‘thinking reality,’ for in its inexhaustible activity it can think all things. The ego is also finite as ‘thought reality,’ because each of its thought acts is limited to a determinate reality. For Fichte, therefore, the ego is conceived as free and absolute activity, wherein life articulates itself by means of an infinity of finite acts. The ego is at the same time ‘thinking reality’ and ‘thought reality.’ The ego is called the pure ego (‘ego’ because it is subject, and ‘pure’ because it draws out everything from itself and thus a priori).     

The Fichtean Dialectic. The activity of the pure ego develops itself in three moments, namely, thesis, antithesis, and synthesis. First (thesis), the pure ego posits (creates) itself. This is the primal act in which the ego, thinking itself, creates itself. The pure ego cannot posit or create something if it first didn’t create itself; neither can the pure ego know something without first knowing itself. Therefore, self-consciousness is necessarily the original principle of any ulterior knowledge. Second (antithesis), the pure ego posits (creates) the non-ego, which consists in the world of reality thought of by the pure ego, and consists in nature and man. The pure ego, creating itself, develops itself in thinking the world of finite realities. If these finite realities are deprived of reason, such as minerals, plants, and animals, the pure ego thinks itself in them in an unconscious manner. If the finite realities are endowed with reason (humans) then the pure ego thinks itself in them in a conscious manner. All these single finite realities thought of by the pure ego are called either ‘non-ego’ or ‘empirical ego’ because the pure ego is infinite ‘thinking reality’ while the world consists in finite ‘thought reality,’ and being finite, not infinite, they are non-infinite, that is, non-ego. The non-ego, therefore, is opposed to the pure ego as finite is opposed to infinite. Thus, the pure ego is one as ego (thinking reality) and is multiple as non-ego (thought reality).[115] Lastly (synthesis), the pure ego performs the synthesis of the pure ego and the non-ego. The one and the multiple, unconscious activity and conscious activity, the pure ego and the non-ego, the Spirit has need of recomposing its original unity. It does this in the moment in which it thinks of itself as man. In this moment Spirit becomes conscious. It understands that the non-ego is its own creation.     

As was said, Fichte’s absolute idealism has a strong ethical character: the essence of the ego consists in will; the world (non-ego) is romantically conceived as an obstacle that must be surpassed. “Why the opposition of the non-ego? Fichte replies that here we can see the creativity of the absolute spirit. It is a creativity by opposition: the ego creates the non-ego as in opposition precisely in order to conquer it and master it, as a self-imposed challenge. And this is the struggle whereby by means of science and of action the ego gradually conquers the non-ego or the world. It is the struggle of the subject to master the object created by it. The real manifestation of the Ego is therefore the will to conquer. The will is the real manifestation of the Ego, and so the moral life (the life of the will) is superior to the intellectual life and to the animal life. Fichte grounds theoretical reason on practical reason more radically than Kant…This is how the Ego fulfils Himself: by mastering the non-ego, and realizing in the end that everything is Ego.”[116]  




Friedrich Wilhelm von Schelling (1775-1854) differed from Fichte in that, though both are absolute idealists, the latter’s philosophy reveals a passion for the struggle to overcome and conquer obstacles, to master the non-ego, while the former sought harmony, love and unity. Fichte was fascinated by dualism and opposition while Schelling was captiviated by monism and union. Fichte had been influenced to a great extent by Kant’s Critique of Practical Reason while Schelling was much influenced by the Critique of Judgment. Schelling had a conception of the absolute as a synthesis of opposites: of the I and nature, of subject and object, of the spirit and the world. The absolute is the origin of nature, the objective form to acquire a greater consciousness of one’s proper subjectivity by means of it. Therefore, nature is the pre-history of consciousness, petrified thought. Man is the being in which the absolute acquires consciousness of itself becoming spirit. The comprehension of the universe, wherein nature and spirit are not anymore opposed against each other, is actuated in aesthetic activity. Works of art are the manifestation of the infinite under finite form. 

In place of the Fichtean pure ego Schelling has his Absolute, conceived as an undifferentiated unity of nature and spirit. Like Fichte, nature is, for Schelling, an unconscious creation of the ego, but while for the former the ego realizes itself first in nature and then in spirit, for the latter nature and spirit proceed in a parallel manner in the sense that the moments of the ego repeat themselves in two parallel series: in the first (nature) in an unconscious manner and in the second (spirit) in a conscious way. The foundation of the two parallel series is the ego, which is undifferentiated original unity. The ego in its origins, is absolute indifference to become nature and spirit.

Nature, for Schelling, is not inert matter but rather a massive living organism that evolves by means of a series of gradations that ascend from matter to life up until self-conscious man. Spirit lives in nature as in a petrified state. Spirit searches laboriously to escape from the unconscious to make itself self-conscious. In such manner, nature is the prehistory of the Spirit. The end of philosophy is the conscious reliving of the various phases of the life of the Spirit that is immersed in nature in a sort of deep slumber. However, the identity of nature and spirit cannot be comprehended either by the theoretical ego (knowing) or by the practical ego (action) but only by art (feeling, sentiment) in as much as art creates as nature does. Only the inspired artist can comprehend the profound mystery of the universe. Only the poet feels, intimates, the absolute in things. For him the world is not that which appears to the common man in the street; rather, it is, for him, almost a symbol, a sign of the Absolute. For these reasons, Schelling’s philosophy has been described as an aesthetic absolute idealism.




Georg Wilhelm Friedrich Hegel (1770-1831) elaborated a pantheistic, pan-logical and historicist, absolute idealism where we find an absolute humanism that generates absolute atheism: man is the immanent foundation of reality itself. He sought to rationally found reality understood as a logical construction of the world. The object of Hegelian philosophy is the rational comprehension of the world and of history. History is characterized by splits between being and non-being, good and evil, the infinite and finite, and God and the world. Knowledge of this reality engenders an unhappy conscience in man who desires to free himself from contradictions. In his work, Phenomenology of the Spirit, Hegel examines in a scientific way the various manifestations of the spirit in its historical dimension. The fundamental principles of the Hegelian system are two: in the logical sphere, that of the identity of the ideal and that of the real; in the ontological sphere, the principle is the absolute in which being is its becoming. Hegel’s method is the dialectic: the sole adequate method for the study of reality is that of speculative logic (or the dialectic). It is made up of three moments: thesis (the moment of being-in-itself), antithesis (the moment of being-outside-itself), and synthesis (the moment of reunion): “For Hegel, there is only one reality, which he calls the Idea. In a sense it is God because there is nothing else, but in another sense it is not God because it has not yet thought itself out and arrived at self-consciousness. The process of thinking itself out is the dialectic. Thinking consists in contrasting each thought with its opposite, whereupon there arises a higher thought which is the union of the two. Thus the thought of being leads to its opposite nothing, and the union is becoming or the passage from nothing to being. In every case the first stage which is simply given or posited is called the thesis, the negation of the thesis is the antithesis, and the union of the thesis and the antithesis or the negation of the negation is the synthesis. What underlies this process is that reality itself is basically contradictory; thought first takes up one side of the contradiction (thesis), and then the other (antithesis) and finally succeeds in fusing the two (synthesis). Any thought contains only part of the truth; there is some truth also in the opposite, and only when both are reconciled in a higher union does the whole truth appear. The process continues because each synthesis now becomes a thesis for further development.

“In thinking itself out, thought arrives at the main antithesis to itself, which is inert matter. At this point the Idea objectifies itself in matter, turns into its opposite, contradicts its unity and totality, fractions itself into this manifold world of experience, spreads itself out to become Nature. This, for Hegel, is the creation of the world. World evolution continues along dialectical lines. The first inkling of synthesis is life, in which thought reappears in matter, organizing plants purposively, manifesting conscious instinct in animals, and arriving at self-consciousness in man, the spearhead of the process. In man the dialectic continues through human history, in which man has passed to higher and higher forms of social organization, culminating at present in the political state. Thus thought and matter, spirit and nature, are united in man. The final synthesis will be a combination of the thesis (the Idea thinking itself out) with the antithesis (the Idea spread out into Nature) into the synthesis (Nature gathered back into the Idea in full self-consciousness as Absolute Spirit). The whole process is the life of God, whose evolution is the universe, of which human history forms a leading part.”[117]     

In Hegel’s system reality is structured by an immense triangular pyramid that explodes from the absolute and develops in an infinite number of triads. The fundamental triad is given by: idea, nature, and Spirit, and the three principal parts are, correspondingly, logic, philosophy of nature, and philosophy of the Spirit. History is the study of the manifestations of the objective spirit. It is the progressive manifestation of the absolute; in it all that happens has a rational character. Evil is only a moment in the dialectic of reason. To manifest itself in history the spirit makes use of the State and of Nation.

As was said Hegel was a pantheist. His “Absolute” is not the transcendent Supreme and Almighty God of Christianity but rather, “this Absolute is immanent in the cosmos, and now specifically in the human consciousness that makes up the human world of history, with its institutions, social entities and movements, and especially its organization into political states. The Absolute is not prior to this world of men or above it; it is not the creating source whence earthly reality derives, nor is it distinct from it. Thus the Absolute is not a ‘substance,’ meaning an existing and already achieved Being or Reality, but rather a ‘subject,’ that is, a process of development in and of and through the earthly human social reality.”[118] For Hegel God is the being of the world and the world is the essence of God.


General Critique of Idealism


Grossly contrary to the certainties of common sense, idealism is an erroneous philosophical doctrine based on faulty logic and the so-called “ego-centric predicament,” as Bittle shows: “The fundamental position of idealism is fallacious. 1. The element common to all forms of idealism is the tenet that reality lies within the consciousness of the perceiver and the mind cannot transcend its own conscious states. It arrives at this conclusion through the difficulty of understanding how the mind can perceive objects at a distance and how a psychical mind can conform itself to a physical object. Hence, there has arisen the idealist postulate that the mind in its knowing can know only its own ‘percepts’ or ‘ideas.’ The argument can be formulated as follows: Objects, so far as the knowing mind is concerned, exist only when perceived; but perception (‘being perceived’) is a conscious mind-state or ‘idea’; hence, objects are only conscious mind-states or ‘ideas’; consequently their existence or ‘being’ (esse) is nothing but ‘being perceived’ (percipi): esse est percipi.

“2. The idealist postulate of idealism is fallacious. Berkeley’s argument that esse est percipi is grounded on faulty logic. His term ‘sensible object’ is ambiguous, because he does not distinguish between the ‘sensible’ as perceived and as perceivable. He merely proves that ‘sensible objects,’ when perceived, are ‘ideas or sensations,’ so that his proof really amounts to the redundant proposition that ‘perceived objects must be perceived.’ The fallacy of idealism thus consists in confusing the statement that ‘sensible objects cannot be perceived as existing without being perceived’ with the statement that ‘sensible objects cannot exist without being perceived as existing.’ To assume that the latter statement is true, is a petitio principii. All arguments which tend to prove that all reality must be identified with ‘ideas’ involve either a ‘four-term’ syllogism, or an ‘undistributed middle,’ or a fallacious ‘conversion.’

“3. The ego-centric predicament, or the difficulty to discover any objects outside the cognitive relationship existing between object and subject, is responsible for the fallacy of idealism. Dualistic and monistic idealism rests upon the primacy of consciousness. Since conciousness is the universal condition of knowledge, it is also assumed that consciousness constitutes the being of all objects of knowledge. Due to the ego-centric predicament, every mentioned thing is an ‘idea,’ and from this idealists conclude that everything is an ‘idea’ and that only ideas exist. But this reasoning is fallacious, because it merely proves that objects, if and when and while known, must be ‘percepts’ or ‘ideas’; in other words, ‘things cannot be perceived without being perceived,’ which is a redundancy and a platitude. The argument, however, does not prove that objects may not exist in themselves, as mind-independent things, without being perceived. The whole attitude of the idealists is based on the confusion of identifying the reality of an object with the perception of this reality; they fail to distinguish between the ‘knowledge of objects’ and the ‘objects of knowledge.’

“The foundation of idealism thus rests on faulty logic and on the ego-centric predicament. The existence of extra-mental things is a question which can be settled only by a close analysis of the facts and by the proper interpretation of the facts; not the a priori, but the a posteriori method can solve the problem.”[119]




In its application as a method, pragmatism holds that a thought is true, not because it agrees with some extra-mental reality, but because it works out right when it is applied to some specific situation; it is false, not because it misrepresents reality, but because, when it is used, it does not work out right. Truth, therefore, for pragmatism, consists in the usefulness of an idea in practice: a proposition is not true or false in itself as an inactive thought in the human mind; it is verified or falsified, that is, made true or false, by proving usable in practice. Pragmatism’s most famous exponent is William James (1842-1910). James’ philosophy is clearly voluntaristic. We see that the dominating aspect of man is will, not reason. With regard to the ultimate questions facing him man attains truth and certainty not with reasoning but rather with the will to believe. It is not reasoning that matters, but rather, will, sentiment, emotions, and feelings.

As was said, the pragmatic is simply what will work, what is in fact effective for present action, and pragmatism finds in this norm the sole criterion for the determination of the truth or falsity of ideas. The very function of the human intellect is ordered towards, and gets its very meaning from, action. The end of knowledge would be none other than the furnishing for the pragmatist with the rules for acting. When the pragmatist discovers these sets of rules, he rests there, content with what he deems to be belief, that is, an immediate and necessary preparation for activity. The entire meaning of what is known lies in the action that is performed; the whole value of human understanding would be found there. Thought receives its value and meaning in its practical consequences.

How is the pragmatic criterion of truth applied to the sphere of our ideas concerning God and religion? The pragmatist applies to the problem of God and religion the same meticulate scientific experimentation that is carried out in a science laboratory towards what something is that he experiences. For example, the most basic examination of what light means in terms of direct experience will reveal that we never experience light itself but rather, human experience deals with things that are lighted. This elemental reality is never modified by the sophisticated physical experiments invented by human ingenuity. From the perspective of operation, light can mean nothing more than the things lighted. Thus, the truth concerning light consists in that it lights objects; a thing is what it does, for it is all that we can know about it.

How does the pragmatist approach the question of God? He begins by affirming that people have a certain common notion about God, namely, that He is. Now, is such a common notion in fact true? It will have to be put to the test by asking if any contradiction would ensue in our activity if God existed. Of course not. Then, the pragmatist must ask if any fruitful results would benefit himself personally and for society in general on the supposition that there is a God. Yes, in fact the pragmatist can furnish a long list of benefits for the person and for society in general from the notion of some Supreme Being. Therefore, the pragmatist concludes, the belief that God exists is true because it benefits man and society; it has been seen to be pragmatically fruitful, therefore it is true. For the pragmatist “God is not something that is known, something that is understood. He is something that is used.”[120]

And what would be false? All knowledge about the nature and attributes of God and all the other endless metaphysical speculations regarding Him. Why? Because they fail the test, not having any practical utility for man and for society. It is true that for pragmatism, the existence of God cannot in any way be rationally demonstrated, for Kant had once and for all made such a demonstration impossible by showing that how man’s notions of causality and finality cannot be valid when applied to God. But the existence of God can be reinstated from a pragmatic point of view, says the pragmatist, for it is undeniable that belief in God does have many beneficial results for both the individual and society. It is possible to gather up a ton load of psychological and sociological evidence with regard to this (i.e., religious persons live longer, are less stressed out, and where religious practice is strong the crime and delinquency rate goes down). God and religion have been put to the test by the pragmatist and, observing the good habits and effects they involve, he concludes that such beliefs are true, that is, useful.

What is the catastrophic error of pragmatism with regard the existence of God? It is in thinking that the empirical methods of science can be applied to the metaphysical problem of being, in particular, to the Subsistent Supreme Being. For the pragmatist, to inquire into reality does not mean to achieve an understanding of being but rather to experiment with our experience as a scientist experiments with his physical data. The pragmatist investigation cannot reveal to us why things are nor why they are what they are, but merely reveal how things operate or how they should operate to obtain useful results. In pragmatism, God is not a being with objective, independent, transcendent, extra-mental real existence; rather, he is a workable hypothesis, an idea that gets things done.

At the conclusion of his influential book The Varieties of Religious Experience, William James quotes with approval Professor Leuba from his article The Contents of Religious Consciousness published in The Monist, who writes that “the truth of the matter can be put in this way: God is not known, he is not understood, he is used – sometimes as meat purveyor, sometimes as moral support, sometimes as friend, sometimes as an object of love. If he proves himself useful, the religious consciousness asks for no more than that. Does God really exist? How does he exist? What is he? Are so many irrelevant questions. Not God, but life, more life, a larger, richer, more satisfying life, is, in the last analysis the end of religion. The love of life, at any and every level of development, is the religious impulse.”[121] And James also quotes, with admiration, the anthropocentrism of W. Bender in his 1888 book Wesen der Religion who says: “Not the question about God, and not the inquiry into the origin and purpose of the world is religion, but the question about Man. All religious views of life are anthropocentric.” “Religion is that activity of the human impulse towards self-preservation by means of which Man seeks to carry his essential vital purposes through against the adverse pressure of the world by raising himself freely towards the world’s ordering and governing powers when the limits of his own strength are reached.”[122]    

Thus, the pragmatist, in confronting the problems of God and religion, asks first of all: are God and religion useful for me? Are there psychological benefits that I can receive from accepting a certain religion and notion of God? Will going to church make me feel good, make me a more popular and loved person? Do God, religion, and church attendance make me live longer? Do they contribute to my getting along with people in society? The pragmatist asks these questions because, for him, God and religion are reduced to their useful function, for the individual and for society.

Critique of Pragmatism. Bittle describes the various contradictions, confusions and inconsistencies inherent in the pragmatist epistemological system, writing that, for pragmatism, which is a voluntarist system, “the truth of judgments does not arise from their correspondence to reality. The pragmatist criterion of truth consists in the utility of a belief in satisfying human needs in a social way. That is true which ‘works,’ which has practical value, which leads to beneficial results for human progress, which promotes the best interest of mankind through living experience. Results make a belief true or false for the time being. Beliefs become true, when they function for the social welfare of humanity; and false, when they cease to function along these lines. Truth is, therefore, nothing static and immutable, but something dynamic and perpetually changing. Consequently, a belief may be true at one stage of development, and the same belief may be false at a different stage; something may be true under one set of conditions and false under another; a theory may be true for one class of people and false for another class, depending on the intellectual and cultural conditions prevailing at a particular time and in a particular locality. Truth, as will be seen, is entirely subjective in character.

“This interpretation of truth is contrary to the accepted meaning attached to the world by all men, whether educated or uneducated, and amounts to a perversion of language. To identify ‘truth’ with ‘utility’ is nothing less than to reduce the ‘true’ to the ‘good.’ The ‘good,’ however, is the object of the will, not of the intellect, while the ‘true’ has been considered by men at all times to be the proper object of the intellect. A lamentable confusion of thought must result from this identification of the ‘true’ with the ‘good.’ If both are identical, so that ‘truth’ is the object of the will, what can possibly be the object of the intellect? As a natural faculty of man it must have a natural object, just as well as the will; but if we remove ‘truth’ from the intellect, the latter is without a proper object with which to exercise its power. The exercise of any power or faculty involves the striving to realize something, and that demands an object within its own proper sphere of activity. Every power or faculty of the human organism, internal as well as external, had its proper object; the will, for instance, strives toward the realization of the ‘good.’ But what could possibly be the object of the intellect except the realization and acquisition of ‘truth?’ There is no other object assignable or discoverable. Pragmatists may assert that the ‘true’ is identical with the ‘good,’ but that will never really identify such totally disparate things. Their attitude is unjustifiable, because contrary to the fundamental conceptions of men.

“Besides, in identifying the ‘true’ with the ‘good,’ pragmatists do not solve the epistemological problem of knowledge. The problem of ‘knowledge’ remains just as acute as before; it cannot be solved by transferring the concept of ‘truth’ from the field of knowledge to the field of action and then denying that a ‘problem of knowledge’ exists. We must still answer the questions: Is there an objective reality which is extra-mental? Can this reality be known? How is it known? How do our judgments interpret this reality? Do they correspond with it? How can we have certitude about this? These questions constitute the ‘problem of knowledge’ and the mind of man will not be satisfied, and will continue to exert its powers of reasoning, until these questions are answered or until the mind sinks in despair into skepticism. But ignore this problem the mind cannot. Whether we call the answers to these questions ‘truth’ or whether we give it another name, makes little difference: it is the problem and its solution that count, and they pertain to the province of the intellect and must be solved by the intellect and not by the will. Pragmatism, therefore, does not solve the problem of knowledge by dubbing it ‘metaphysics’ and then ignoring its existence.   

“And pragmatists are inconsistent. They identify ‘truth’ with ‘utility’ and thus transfer it to the province of the will. Nevertheless, they appeal to the intellect with a great array of arguments, to prove that ‘truth’ is to be judged according to its beneficial results. Thereby they surreptitiously substitute the intellect for the will as the arbiter of truth and error and unconsciously admit after all that it is in the intellect, and not the will, which must decide whether their theory or opposite theories give the correct (or ‘true’) solution of the problem of knowledge and truth. Since they appeal to the reasoning intellect, they must abide by its verdict. Now, it is the verdict of the reasoning intellect, as we have shown, that truth is found in the judgment interpreting reality and not in the results which flow from a certain belief. It is not ‘utility’ which determines the ‘truth’ of judgments, beliefs and theories, but the objective evidence of reality. In fact, when pragmatists attempt to prove their own theory, they marshall numerous facts and reasons in order to show that ‘utility’ and not ‘objective evidence’ is the criterion of truth and the motive of certitude; and in doing so, they appeal to the objective evidence of these facts and reasons to establish their case. Their own attitude and action is their best refutation.

“Moreover, pragmatists claim that those beliefs are ‘true’ which satisfy human needs and produce beneficial results for man in a social way. What needs, and what beneficial results? We must know them, so as to be able to ascertain which beliefs contain ‘truth’ and which ‘error.’ In order to know whether needs are real or apparent and whether results are beneficial or harmful, it is necessary for the intellect to discover the facts regarding these needs and results and then pass judgment on the truth or error of the beliefs. But here again, if any judgment corresponds to the facts at issue, it is ‘true’; and if it does not, it is ‘false.’ Thus it can be seen that truth and error reside in the judgment and their presence is determined by the objective evidence of the facts. The good results may be taken as an index or sign of truth, but the ultimate criterion of truth lies in the objective evidence before the mind. As long as it is necessary to have a criterion to discriminate between ‘real’ and ‘apparent’ needs, between ‘beneficial’ and ‘harmful’ results, between beliefs which ‘work’ and those which ‘do not work,’ results cannot be considered the ultimate criterion. Results do not appear with labels attached; they can be discerned only by the intellect. Even from a pragmatist standpoint, then, the truth or error of beliefs cannot be decided without the judging power of the intellect. The ultimate criterion for the intellect, however, as has been seen, consists in the clear self-manifestation of reality or self-evidence. Hence, pragmatism does not satisfy the ‘needs’ of the intellect as a theory of truth and knowledge and, judged by its own criterion, is unsatisfactory and therefore false.

“Finally, how can I apply the pragmatist criterion to everyday existential judgments? I judge that ‘My watch is slow,’ ‘a car is passing,’ ‘my feet are cold,’ and so on. These statements contain truth or error. By what possible results for human progress and welfare am I to decide whether they are true or false? Or will a pragmatist seriously assert that there is no truth or error in these and similar judgments? If he claims there is not, we must dissent; if he agrees that there is, he must admit that his criterion does not apply. A criterion, however, which fails in its essential function, is worthless, because it is no criterion at all: it does not ‘work.’”[123]










The neo-positivism of the Circle of Vienna,[124] basing itself on the principle of verification, had declared metaphysics and religion to be meaningless, reducing them to the level of irrationalist sentiment. For the neo-positivist or logical positivist system all philosophical problems must be resolved through a sole analysis of language, linguistic analysis being identified as the proper task of philosophy itself. All propositions that make sense are only experimental, factual, or scientific propositions. Metaphysical propositions like “God exists,” as well as those propositions of religion, ethics and aesthetics, are deprived of content inasmuch as every content must be derived from experience, and so, for the neo-positivist, affirmations like “God exists” and “the human soul is immortal” are nonsensical. The central thesis of neo-positivism is that the fundamental propositions of metaphysics, ethics, religion, and aesthetics, are simply meaningless, for they fail the test of empirical verifiability.

Neo-positivism or logical positivism is an attempt to establish the validity of what man knows by an analysis of what he says. After all, man’s knowledge of reality is expressed in propositions, so that a linguistic analysis should reveal whether a given proposition is meaningful or simply verbal manipulation. Neo-positivists and logical positivists agree that the Humean view of causality and empirical induction are givens, and that all philosophy is, in fact, logical analysis, that is, it consists in the analysis of the language which ordinary people speak. There is also a common point of agreement in the fact that such a linguistic verification eventually leads to the rejection of metaphysical propositions such as those about causality, substance, accidents and so forth. Such metaphysical statements are to be declared meaningless, at least in their original intent. A certain proposition can only be sensical, and therefore “true,” if the elements of such a proposition, after a linguistic analysis, can be reduced either directly or indirectly to some sense experience or some sense data. If this is not possible, then the proposition is rendered nonsensical or meaningless.

An example. What does the common expression “apples exist” mean? This philosophical system will answer that there are no such things in reality as “apples,” for this is simply a verbal constant applied to what is an almost unlimited number of sense impressions and sense references, organized and focused upon by the thinker. The logical positivist declares that there can be no such thing in reality as a substance “apple,” and since this is a fact, “apples” do not exist. Locked up in an anthropocentric immanentism and empirical phenomenalism, it is not possible to apply the existential metaphysical word “exist” to “apples,” but only to the conglomeration of what is sensibly perceived when we see what we “call” an apple. Ideally, a proposition like “apples exist” would have to read: “there is something such that this something is an apple.” But can the expression “apples exist” have any meaning? Yes, for such an expression can be directly reduced to sense experience and sense data.

What happens when logical positivism is applied to the problem of the existence of God? To ask the question “Does God exist?” is to ask whether the expression “God exists” has any meaning; whether it is possible to reduce it, either directly or indirectly, to sense experience. The answer is an obvious no, for it is impossible to have an experience of the verbal elements in any way; the proposition cannot be transcribed in terms of any known experience. Therefore, the expression “God exists” is meaningless; not true or false, but simply nonsensical. Aside from adopting the erroneous positions of Humean empiricism, logical positivism adds its own so-called “principle of verification” which is the principle that maintains that every meaningful proposition must be verifiable in sense experience. The only trouble with such a principle is that it fails to pass its own test: the principle of verification is itself unverifiable in sense experience; it is a metaphysical principle grasped by the intellect and not by the senses. 




Edmund Husserl (1859-1938) is the founder of phenomenology, a type of philosophy which studies essences outside of their existences insofar as they are manifested to the contemplating consciousness of the knowing subject. Phenomenology was born as a reaction against the scientistic positivism and materialistic naturalism of the late nineteenth and first half of the twentieth centuries, which attempted to reduce man to a spatio-temporal physical being, deprived of freedom and self-determination.     

The phenomenological method consists of two principal moments, namely, the negative and the positive. In the negative moment, which Husserl calls epoché or phenomenological reduction, the object is isolated from all that is not proper to it in order for it to reveal itself in all its purity. For Husserl, facts are grasped by a sensible intuition, which are limited to spatial-temporal coordinates, but nevertheless contain a universal and necessary essence, which can be known by “bracketing out” or “placing between parentheses” their existences, which are contingent and variable. By means of this phenomenological eidetic reduction there emerges to the consciousness of the knowing subject ideal nuclei – essences – like flower, pot, tree, red, which lead to the intuition of essences. In the positive moment of the phenomenological method, the gaze of the intelligence is directed towards the object itself, immersing itself in it and leaving the object to manifest itself. This, for Husserl, is an authentic intellectual intuition (a vision and not a Kantian construct of the mind), corresponding to the evident and objective presentation of phenomenical essences as manifested to human consciousness.

It should be noted that, even though Husserl constantly makes use of the Brentano-inspired theme of subject-object intentionality (and doing so he goes against the excesses of absolute, subjective idealism), nevertheless, his intentionality is immanentist-inspired; it is not directed at external reality, the trans-subjective world that really exists, which is the case with the moderate realism of Aristotle and Aquinas, but rather toward ideal objects, which are found within the sphere of consciousness. The Husserlian phenomenological method is not concerned with individual, real existence (which is the case in Aristotelian-Thomistic realism) as it is bracketed out, placed between parentheses, and consequently, such an immanentist methodology can be aptly described as a sort of mathematically inspired non-metaphysical Platonism gravitating towards idealism.   

Sanguineti has noted that “the idealistic turn was not lacking in Husserl, who speaks of a phenomenological reduction, through which is placed between parentheses the entire phenomenal world, reascending to its original root, the trascendental ‘I’. The phenomenological epoché, according to Husserl, implies the abandonment of the natural attitude of the person who believes that he lives in a world of existent things. In a mode somewhat similar to Cartesian doubt, one suspends every judgment on the existence or reality of phenomena of the consciousness (a judgment not yet precluded in the eidetic reduction), and finally one arrives at the constitutive principle of every phenomenical appearance – that is, at the consciousness where the phenomenon appears. In any case, the ‘I’ is an irreducible phenomenological residue, an absolute element, even if intentionality makes of it a cogito cogitarum, always turned to the object.”[125]

In contrast to the idealist, immanentist phenomenological method of Husserl, authentic realism (i.e., Aristotle, Aquinas) “intends to know essences as they are, not as they present themselves to human knowledge. Hence the use of analogy, of rational discourse (which phenomenology does not utilize), and the use of concepts such as act-potency, substance-accidents, being-essence, which refer not to the isolated essence of a thing, but to the profound contents of the real being of things…The risk of the phenomenological method, if used exclusively, is the distancing from the world of nature, abandoned to the hands of the positive sciences, and also the detachment between two spheres, that of the real world and that of the “I” with its contents of consciousness. Categories such as substance and causality are generally rejected by phenomenology as ‘naturalistic’ or as bound to the sciences.”[126]     

Criticizing Husserl’s alleged adherence to realism, De Torre writes that, according to Husserl on the epoché, “Whenever we focus on any noema, we have to isolate the original essence referred to by its intentionality from all the subsequent accretions added to the concept culturally and historically, including the very existence of that reality outside our consciousness of it. The epoché is therefore used as a bracketing: I put in brackets all that is not of the original essence referred to by the intentionality of the noema or concept under consideration. Not that I reject or eliminate those additions to the pure essence: I simply suspend my judgment on them. I do not consider, for example, whether a real tree exists or not: I only try to grasp and describe what the ideal object tree represents such as it presents itself to my noetic consciousness. The first thing to put in brackets is the existence itself of that essence outside my consciousness. For instance, when we consider the concept of immortality, the first thing we have to put in brackets is whether there is such a thing as immortality, and focus our attention on the meaning of the term referred to by its intentionality. The entire world is given to us in our consciousness, and therefore it would be naïve to study the existence of those things outside our consciousness: what we have to study is their essence. This is what Maritain has dubbed the Husserlian refusal: the refusal to accept being on its own terms.[127] The aim of the phenomenological reduction is to arrive at a pure, almost mathematical, grasp of an a priori essence, necessary, detached from existence, which is merely factual, transient, contingent. For Husserl, this is the only way to surpass historicism and positivism, and make philosophy a rigorous science. Husserl’s doctrine in this regard thus follows the rationalist pattern of dividing reality into ideal essence and factual existence, making philosophy a knowledge of essences. Classical rationalism, however, tried rather to elaborate a deductive system starting from a priori definitions, while Husserl’s phenomenology, more attentive to the contents, intends to describe essences. But immanentism cannot be overcome in this way. For Husserl every object is such to the extent that it presents itself to the consciousness which makes the phenomenological reduction. ‘All transcendence comes about only in the life of consciousness.’ That is why the only thing which cannot be put in brackets is the ego, which is like the top or ceiling which cannot be surpassed. Husserl holds on to the Cartesian cogito, but now it is a cogito cogitatum, a thinking about the world: I in the world; an ego and a world which are seen as inseparable poles. ‘In proceeding thus’ writes Husserl towards the end of his life, ‘one has always anew a living truth drawn from the living source of the absolute life and a self-consciousness turned towards that absolute life in a constant sentiment of responsibility to self.’ Granting that this is not constitutive idealism (the ego creates the world), it is however immanent idealism (ego and being correspond to each other): in this, Heidegger will follow him. In actual fact, in his last years, Husserl gave his allegiance clearly to idealism, which is the logical sequence of his approach: ‘Only he who does not understand the meaning of intentional analysis, or the meaning of the transcendental reduction (epoché), or both, only he can attempt to separate phenomenology from transcendental idealism.’[128][129]











Knowing always involves a knower knowing something. It involves a relationship between a knower and the known. It is an act which joins a mind with an object in a relationship which is unique and incomparable with any other. There is no such thing as knowledge without something known and a knowing subject knowing it. Each and every act of knowing is a synthesis of object and subject. Because of the relation between two beings, the knower and the known, man does not remain a closed being, like a block of granite or a piece of red brick. Rather, he is able to “open himself up” so to say to the world around him; he is able to transcend himself, to go “out of himself” and enter into communication with other beings. However, the act of knowing is something inverse; it is the extra-mental thing that, in a certain manner which we shall explain, is received into the human subject, as knowledge is a preeminently immanent action, taking place, not outside but within the knowing subject.   

There are three basic elements of knowledge, namely: 1. the subject or the knowing being; 2. the object or that something known (before it is known it is called the knowable object, and during or after the act by which it is known it is called the object known); and 3. the act of knowing called cognition. When all these elements join together the resultant product is an act of knowledge or cognition.   

Purely physical beings don’t know. A rock doesn’t know. A glass doesn’t know. A glass receives another being, water for example, in the most superficial manner. Any more intimate communication would mean a loss of identity, becoming something else. Fire united with wood produces something new: ashes. A substantial change has occured. The union of hydrogen and oxygen results in a third thing: water.

Why does a man know while a rock does not know? It is because a rock has only its own form while a man is capable of receiving the form of the rock and countless other beings in the universe in an immaterial way. When a man receives the form of the rock in the knowing process the change involved in this knowing is immaterial, not substantial-material (as when an apple is changed into my flesh when I eat it or when fire reduces a piece of wood into ashes). The rock that I know does not change its being and my flesh does not turn into stone when I think of it for the stone is not transferred into my mind in a material way. The rock exists in me in an immaterial way. The rock that I know is one whole thing that really exists in the world whether I think of it or not. The real object - which here is the rock - is one, while its intentional presence is multiplied according to the number of knowers. If five hundred persons know a single rock, its intentional presence in the minds of these five hundred persons is five hundred.

Immateriality,[130] therefore, is at the basis of our knowledge. Nothing can be known unless it has in itself something not matter which it can give to us (in the case of our rock it is its form or rather forms – substantial and accidental). And we are unable to know unless we have within ourselves something not matter which can receive the nature of another thing without losing our own. Therefore, the condition both of knowledge and of knowability is a certain degree of immateriality. My knowledge of rocks is something I can communicate to a classroom full of students. But I do not lose this knowledge by communicating it to, say, a hundred students.

In knowledge the object gives its forms to the subject without losing these forms. Form is communicable; matter is not. In knowledge I receive the form of things in an immaterial way. Now, what exactly is this form we are referring to? There is something immaterial in every actual being, even in every material being such as our rock. This something is the form, or rather, the forms - substantial and accidental. Every corporeal substance is a hylemorphic composite, that is, an essential composite of primary matter and a substantial form and is determined in many ways by accidental forms.

Hylemorphism is the theory of matter (hyle) and form (morphe). It states that every natural substance, that is, every complete material substance, is a composite of two essential intrinsic principles, one a principle of potentiality, viz., primary matter, and the other a principle of actuality, viz., substantial form. “Prime matter, which is the common substrate of all bodies,” says Glenn, “has itself no determinateness, nothing to make it actual, nothing to make it this or that kind of body, but waits, so to speak, for the coming of the substantial determinant which will give it actuality as materia secunda (secondary matter), a finished body of definite type actually existing. Prime matter is thus the subject of the determining element which gives it existence as a substance. Thus we may define prime matter as follows: ‘A passive and indeterminate substantial principle which is the subject of all substantial determinations and substantial changes, and which remains changeless in itself under such changes.’”[131] Form on the other hand, the most important of the two, is determining and definitive, determining prime matter to substantial being, to a definite species of being, giving it a definite nature. Form, which is the determination of the essence, is what makes the essence to be what it is. It is the act of the essence, the essential act determining the essence to be what it is. The substantial form of our hylemorphic composite, Glenn states, is defined as “an active and determining substantial principle which is the term (that is the goal, the end, the completed being) of all substantial changes in bodies, and which constitutes each individual continuum in its essential actuality.”[132] There is not just the substantial form of a thing but also the various accidental forms (e.g., quality, quantity) which pertain to that existing being (ens). “Any form is a cause in relation to the matter it ‘in-forms,’ since it gives that matter the actuality of a determinate manner of being. The form without which a being would be nothing at all is called substantial form. Those forms which affect an already actual being by conferring on it further modifications are called accidental forms. The substantial form gives a thing its basic manner of being, making it a substance: a man is a man and therefore he is, because of his soul. The accidental forms, in contrast, only give a substance certain secondary configurations, which obviously can only affect something which is already a substance. The substantial form is the act of prime matter, which is the subject which receives it. Accidental forms modify the substance (the secondary matter) which supports them.”[133]

All the corporeal things around us are composites of matter and form. Form is that which makes a thing what it is, giving them their basic way of being: manness, catness, whaleness, and so on. But manness does not exist by itself. Individual men exist: Paul, Billy, Edward, Bobby exist. Likewise catness does not exist by itself but only individual cats – that cat down the street, that brown cat on the top of the roof, that black cat crossing the highway, etc. Form alone, then, is not enough to explain the actually existing men, cats, and whales in our world. There must be something else in things, something which limits them, which ties them down to this particular way of being and not any other, to this particular time and place, to this quantity. There must, in short be another principle in things, a principle of limitation, a principle which limits form, restricts it in a way, making it individual, quantified, existing in a definite time and place. This principle is matter.


Overcoming of Contrareity and the Principle of Assimilation


Now in the act of knowing, which is a psychic act, we do not get the matter of things into our mind but instead receive their forms (accidental and substantial). And it is by means of the forms of things in us that we get to know these extra-mental things. We receive the forms of various things in an immaterial way through a psychic act. “The insertion of the formality into the cognitive potency,” writes Sanguineti, “allows knowledge in act, according to two Aristotelian principles: 1) Overcoming of contrariety: material objects are receptive of sensible qualities, but the natural presence of a concrete quality impedes that of another: that is, the sensible qualities are contrary elements, which exclude one another reciprocally. Instead, knowledge surpasses contrareity. For example, the faculty capable of receiving colours immaterially must not only be uncoloured, but rather incapable of undergoing the determination of a natural colour; having in itself the ‘receptive potency’ when confronted by every colour, it rests above the concrete colours – that is, it is in a certain sense situated in the appropriate ‘genus’ in order to be able to objectivize any colour, distinguishing one from the other.        

“2) Principle of assimilation: the cognitive potency initially finds itself in an ‘objective vacuum,’ while it does not know anything in act (even if it can know everything that enters into the scheme of its formal object). Knowledge consists not only in the grasping of a form, but in the identification of the faculties with the known form. The cognitive potency passes into act when, being able to receive the form of the thing, it appropriates this latter to the point of making it its own. Since being is specified according to the form, when the cognitive potency is ‘informed’ by an object, it can be said that it acquires a being according to such an object: the sight that sees a colour makes itself that colour, in terms of an intentional identification with its object. In the act of knowing, the knower is the known, precisely because the former has assimilated the latter – made similar to the same – and appropriated it.”[134]


The Intentional Species


The form in the cognitive power of the knowing subject is called the intentional species. This species is an actuation of our cognitive power. The species is not that which we know but is rather that by which we know the thing that really exists. Knowledge is produced thanks to the actuation of the intentional species in our cognitive power. Species here does not signify a logical principle which determines predicational existence, nor does it signify an ontological principle which determines natural existence; rather, it is a gnoseological principle which determines intentional existence. So, in its cognitive meaning, a species is an intentional form. As an intentional form it is an instrument of knowledge. Renard explains the nature and role of the intentional species in cognition, writing: “The faculty of knowledge in man, whether intellect or sense, is primarily a passive and indeterminate potency. It must somehow be actuated, moved from potency to act, by the object, since the object is a real cause of knowledge. This actuation implies the reception in the faculty of an immaterial form which renders the object present. We call this form the ‘re-presentative’ species or image. We should note, however, that the being of the object ‘received’ in the knower is not the physical object which exists distinct from the knower, but a form or species[135] – a more or less perfect likeness – which presents not merely the form of the object, but the whole object, the composite of matter and form. This likeness, this species, is called the object in the intentional order. This same species, when viewed not as a ‘re-presentation’ but according to its own reality in the order of nature, is an accidental form, and as such it is united physically with the operative potency, the cognoscitive faculty of which it is the actuation.

“Now, if we consider the union which takes place in the order of nature between the species (as an accidental form) and the operative potency (which is an accidental form of the knowing subject), we must say that this union is a physical union of act and potency This is so because the species is the actuation of the operative potency, and the resulting composite is neither of its parts; it is something else, a third ‘something,’ namely, the actuated faculty. If, however, we consider that the form received is the likeness of the object, and that by means of this likeness the subject knows the object; and if, moreover, we consider that both forms – the operative potency and the species – are acts (perfections) and are immaterial,[136] we must infer that this union is a peculiar union of act (perfection) with act, through which the subject becomes the object in the operation we call knowledge.

“That the species must be immaterial is easily shown. The reason is that the subject must somehow be immaterial in order to know. The object, being received in the knower, must also be free from matter according to the degree of immateriality of the subject, since whatever is received must be received according to the nature of the receiver. It follows, then, that a corporeal object will have to be received in the knower as a ‘representative,’ immaterial form, a species, by means of which the operative potency will unite itself to the object.[137] It is unthinkable that a corporeal, individual substance, existing by its natural ‘to be,’ could be received in an immaterial subject, and be united to the knower in an intentional union. We conclude: the species, which is the actuation of the cognoscitive faculty, is an immaterial form.”[138]    


Being (Ens) is That Which is First Grasped by the Intellect


What is the formal object of one’s intelligence? It is being (ens). The first thing that falls under the grasp of the intelligence is being (ens) because the comprehension of any type of thing involves a preceding comprehension of its character as being (ens). The complex concept of being (ens) is the first idea formed by the human mind, which is not innate but proceeding from experience, in which man notices being as soon as he intellectually knows. One does not therefore treat of an explicitly abstract idea which emerges later as the result of a greater elaboration, but rather of the fact that anything that is the object of some comprehension is first grasped under the character of being (ens). “The apprehension of the real,” writes Llano against critical realism, “is immediately resolved into that of being. It is not possible to found the apprehending of reality on a previous grasping of causality, as critical realism would have it, because the notion of cause depends on that of being, and not vice versa. ‘To begin with an awareness of internal experience in order subsequently to demonstrate the external reality of its object with the help of the principle of causality is, evidently, to introduce the very demonstration as an intermediary between psychological experience and its object.’[139] The approach of critical realism attempts to go from what is apprehended to the real. Metaphysical realism, in contrast, starts out with real being. ‘Because, no matter what object I apprehend, the first thing I grasp about it is its being: ens est quod primum cadit in intellectu. Now this being, which is the first object of the intellect…is very far from being something apprehended without the real; it is, in fact, the real itself, given, doubtless, in an apprehension, but not inasmuch as apprehended. If the thing which experience offers for our analysis ought to be decomposed according to its natural components, it is still undoubtedly ‘an apprehended real thing’ which is being presented to us by our experience, and no method authorizes us to present it as ‘a real apprehension’ unless we change its structure.’[140]

“Starting with the first intellectual illumination of experience, we progress in our knowledge of being. The real panorama which our senses and our intellect offer us is not static, but made up of changeable realities. The movements of things, their activity, their mutual influences, reveal a real capacity on the part of beings for receiving and communicating perfections. The consideration of this natural dynamism leads us to the knowledge of passive potency – the capacity to be determined – and active potency – the capacity to determine – in things.”[141]


Definition of Human Knowledge


After all that has been presented in this chapter, can we give a definition of man’s knowledge? Yes. Renard gives us a descriptive ‘definition’ of human knowledge, stating: “Human knowledge is an immanent operation enacted through the operative potency which has been actuated by a representative species of the object, thus enabling the knowing subject by its operation to become intentionally united with the object.”[142]








The Process of Knowledge


Man is endowed with sense knowledge; he has various external and internal senses. But being a rational animal (a definition of his metaphysical essence) he not merely senses and imagines but also has the capacity to abstract, form judgments, reason and reflect upon himself and his own actions. Man’s ideas or concepts are not the actual products of sense though they are initially derived from sensory data through the instrumentality of the intellect. The object of the senses is a sensible, and the object of the intellect is an intelligible. The medium of both sensible and intellective knowledge is what is called a species. An image is a species of a sensible order of being and an idea or concept is a species of an intelligible order of being. An idea is not an image of a superior sort; to identify them would be to fall into the error of sensism of which Humean empiricism is a pre-eminent example.

We shall now describe the important process of the birth of the idea (idea being the intellectual representation of a thing). First, let us give a purely descriptive account of the knowledge process and, later, an explanatory account. First the descriptive. We form ideas in our minds only after having perceived things, and in forming these ideas we are governed by the perceived aspect of things. What is the process of human cognition from sensitive knowledge to intellective knowledge? The following: 1. The human person, a hylemorphic composite of body and soul, endowed with the operative faculties of intellect and will, is affected in his various sense organs by extra-mental bodies, things, perceiving through the power of his external senses (and unified by the central sense) these extra-mental bodies or things and their corresponding sensible determinations; 2. He then forms, by his internal senses, sensible representations (i.e., phantasms or images) of these bodies with their qualities, operations, etc.; and 3. Finally, by his intellectual power, he grasps in and through these sensible representations the essence or quiddity of the extra-mental things and their corresponding qualities, operations, etc., expressing these essences by way of wholely immaterial, universal representations called ideas or concepts.


Sense Knowledge


Before dealing with sense knowledge, we must first of all establish what sense, sensation, and perception are. A sense is a specialized function by virtue of which an animal organism is receptive and responsive to a particular class of physical stimuli, resulting in knowledge. A sensation is a conscious experience aroused by the stimulation of an organ of sense. Lastly, perception is the cognizing of the object which produces the sensation. Man, as well as the more developed animals, have external and internal senses. Man has five external senses and four internal senses.


Sense Knowledge, the Nervous System and the Brain 


How is sensory knowing connected with our nervous system and brain? The nervous system is the foundation for our capacity for sensory knowledge. By means of the nervous system we receive, process, and respond to the various sensible data from the outside world. The basic building block of the nervous system is the neuron which transmits electrical signals from one location to another within this nervous system. The greatest concentration of neurons is located in the neocortex of the brain, which is associated with various more complex cognitive processess. According to Sejnowski and Churchland[143] there can be as much as 100,000 neurons per cubic millimeter in this tissue. Neurons have four basic parts: 1. a Soma or cell body (containing the nucleus, is responsible for neuronal life and dendrite connection to the axon); 2. Dendrites (which are receptive of data from other neurons, while the soma integrates the information. Human learning is associated with the formation of new neuronal connections, and consequently an increase in the ramification or complexity of brain dendrites); 3. an Axon (which responds to information by electrochemical signal transmission which ends up in the terminus or end where the signal is then transmitted to other neurons), and 4. Terminal buttons (small knobs found at the end of axon branches which do not directly touch the dendrites of the next neuron. Instead, there is a minute gap, called the synapse, serving as a juncture between terminal buttons of one or more neurons and the dendrites (or at times the soma) of one or more other neurons. Studies have shown that synapses are important in cognition. Animal experiments reveal that laboratory rats that learn new things show an increase in both the size and number of their brain synapses.[144] In humans, the decrease in cognitive functioning as a result of Alzheimer’s disease is associated with the reduced efficiency of synaptic transmission of nerve impulses.[145] When the terminal buttons release one or more neurotransmitters at the synapse signal transmission between neurons occurs. Neurotransmitters are the chemical messengers for data transmission across the synaptic gap to the receptor dendrites of the next neuron.[146] They are responsible for intercellular communication in the nervous system. Among the many neurotransmitters that we know, those associated with cognition, memory and learning include: 1. Acetylcholine (a monoamine neurotransmitter synthezised from chlorine); 2. Dopamine (a monoamine neurotransmitter synthezised from tyrosine; 3. Gamma-aminobutyric acid (an amino acid neurotransmitter); and 4. Glutamate (likewise an amino  acid neurotransmitter).

With regard to the human brain, its most important structures related to sensory cognition include 1. the Cerebral cortex (which has a controlling and coordinating function with regard to sensory cognition); 2. the Hippocampus (which plays an essential role in memory formation as well as learning); 3. the Thalamus (located in the center of the brain, around the level of the eyes, relaying sensory information to the cerebral cortex)[147]; 4 the Midbrain, including the superior colliculi (involved in vision), the inferior colliculi (involved in hearing), the reticular activating system (involved in consciousness and attention); and 5. the Pons (involved in consciousness, relaying information between the cerebral cortex and the cerebellum).    


A. The External Senses


All man’s knowledge begins with sense knowledge gotten initially by means of the external senses. These senses are called external, not so much because their receptory organs are close to the external surface of the body but rather because these senses directly reach extra-mental reality. “What is meant in general by an external sense,” says Owens, “is a faculty whose exercise gives awareness of extended and qualified objects existent outside our cognition. With ‘external’ taken in that meaning, the designation is sufficiently apt. The five traditional senses make us immediately aware of things that exist in themselves in the real world, things such as chairs and tables that we see and touch, food that we taste, perfume that we smell, or the singing that we hear. Kinesthetic and pain sensations make us aware of what is going on inside our body. Yet the pain and the motion are occurring in reality and are not existent solely in our cognition. From that viewpoint the faculties that provide awareness of them may be classed with the external senses, because they bring us into immediate contact with what is external to our cognition. The fact that all the external senses are faculties internal to the percipient and his or her perception need not cause any distraction. In every case, then, external sensation makes us aware of something that has existence in reality, in contradistinction to something that exists merely in our cognition.”[148]

How do we define the external senses? James Royce gives us a good definition and explanation of the parts of this definition: “An external sense” he says, “may be defined as a power by which we experience the quality of a material object stimulating a receptor organ. Let us examine this definition: ‘Power.’ The sense is the power, sensation is its act. (Avoid the wider connotations of the word ‘sensation,’ which imply urge or excitement.) Obviously we are not aware of the power directly but make the easy inference that if we experience the sensations we certainly have the ability to do so; that is all that is meant by sense power. The power, then, is a property of the organism by means of which it is able to perform this particular operation. ‘By which.’ Note that the power is not that which knows, but only that by which man knows. ‘Experience.’ This experience is an awareness, the simplest form of knowledge. Again we insist that this experience practically never occurs in isolation, but as part of a total perceptual process which involves the activity of the internal senses and perhaps also of the intellect. ‘Quality.’ The proper object of a sensation is the color, flavor, odor, or similar quality of a material object in question. This object is called a sensible, or sensible quality. It may be proper or common. (The total awareness of the substance which has these qualities is called perception). ‘Material object.’ Sensory knowledge is organic, animal. By it we can only be aware of material objects and in a material way. ‘Stimulating.’ Sensation is always a matter of present stimulation, the action of the object on the receptor organ at the present time. It is by means of the internal senses, such as imagination, that we can be aware of objects even in their absence. ‘Receptor organ.’  The receptor or end organ is the particular part of the body which is designed to receive the stimulation and is the instrument of sensory consciousness.”[149] The external senses are five in number, namely, touch (or the collection of somesthetic senses), smell, taste, hearing, and sight. 


1. Touch (or the Collection of Somesthetic Senses)


Touch is a generic name for several more or less distinct species of senses involving contact between a sentient body and an object. These senses are called the somesthetic senses, and consist in exteroceptive cutaneous senses, as well as the visceral and static interoceptive and proprioceptive kinesthetic intraorganic senses. An exteroceptive sense is one which is activated by various stimuli originating outside the organism. The somesthetic senses of warmth, cold, pressure and pain belong to this class. An interoceptive sense, instead, is a sense which is activiated by various stimuli originating within the viscera and within the vestible of the internal ear. Finally, the proprioceptive sense is the sense which is activated by various stimuli produced from within the organism by movement or tension in its own tissues. Such is the kinesthetic sense. Summarizing this collection of somesthetic senses, Bittle writes: “The Cutaneous or Skin Senses. The cutaneous senses are located in the skin region, and they are the senses of pressure, pain, warmth, and cold. The skin contains various types of nerve endings associated with the cutaneous sensations: capsules, Pacinian and Meissner corpuscles, Krause bulbs, and the end organs of Ruffini.

The Sense of Pressure. The stimulus is anything which, upon contact, alters the even surface of the skin. Hair follicles serve as receptors of touch and pressure; most likely also Meissner corpuscles and perhaps free nerve endings.

The Sense of Pain. The stimulus is some object which injures or nearly injures nerve tissue. The pain receptors are the free nerve endings.   

The Temperature Sense. Investigators associate the sensation of cold with the Krause bulbs and that of warmth with the end organs of Ruffini; others look for the true stimulus source in the blood vessels. The sensation of ‘heat’ results from the stimulation of adjacent warmth and cold spots.

The Visceral Senses. The visceral senses and the static sense are interoceptive. The visceral senses have the source of their stimuli in the viscera or vegetative organs. There are several kinds of visceral sensations: some pertain to the musculature, some to the nutrition system, some to the digestive tract, and some to the respiratory and circulatory systems. It is doubtful whether any special senses participate in visceral sensation; apparently, the receptors of pressure, pain, cold and warmth combine in various patterns and thus give rise to visceral sensations.

The Static Sense. It is an intraorganic sense, the end organs of which lie in the internal ear and are stimulated by the pull of gravity and by head movement. The organ consists of the semicircular canals, ampullae, urticle, and saccule. The canals, with their endolymph, acquaint us with the rotary movements of the head. The urticle and saccule, with their otoliths, acquaint us with any deviations of the head and body from their normal positions. The static sense is a sense of positional equilibrium and orientation in head movements.

The Kinesthetic Sense. It mediates sensations of the position and of the active and passive movements of the bodily members. We also experience sensations of resistance and weight. The organs are probably muscle spindles and tendon spindles. Corpuscles of Ruffini and Pacini, in all probability, also play a part in these sensations.”[150]  


2. Smell


Smell (also called olfaction) is an external sense by which the odorous properties of bodies are made known by means of the stimulation of receptors responsive to various chemical substances in gaseous form suspended in the air or to small particles likewise suspended in air or gas which manage to reach these receptors. Smell’s organ is the nose, or more accurately, the olfactory bulbs in the mucous membrane of the nose. The proper sensible object of smell is odor, which is grasped when the smell’s organ, the nose, comes into contact with particles of “odorous” substances suspended in air or gas. For example, a cook is frying chicken. The informational medium of smell would be the molecules released by the frying of the chicken. The proximal stimulation would be molecular absorpton in the cells of the olfactory epithelium, the receptor surface in the nasal cavity. This happens when various odorous particles enter the nostrils through the breathing in of some form of gas in which the particles are suspended. The general classification of odors are as follows: fragrant, fruity, resinous, spicy, putrid and burned. 


3. Taste


Taste (also called gustation) is an external sense by which certain qualities of soluble substances, such as flavor, savor, are made known through contact with taste buds (epithelial end organs) located mainly in the papillae of the tongue. The organs of taste are the tongue and certain parts of the palate and throat, or, more specifically, the taste buds on these parts of the body. The object of taste is flavor, which is divided into four kinds: sour, sweet, salty, and bitter. An animal or a man experiences flavour when certain soluble substances are brought into  contact with the taste buds. A man, for example, bites a slice of newly cooked bacon. The informational medium would be the molecules of the bacon released into the air and dissolved in water. The promixal stimulation would be the molecular contact with the taste buds, the receptor cells on the tongue and soft palate, combined with olfactory stimulation.


4. Hearing


Hearing (or audition) is the external sense by means of which sounds are known. Hearing’s proper sensible object is sound (either tone or noise, the difference dependent on the regularity of vibration in the air waves), which is experienced when a vibrating surface communicates its motion to a medium in contact with the ear. Sound waves are conducted to the basilar membrane, the receptor surface within the cochlea of the inner ear. The receptor organ of hearing or audition is Corti’s organ in the inner ear “where,” says Royce, “the endings of the auditory nerve are arranged along the inner windings of a small body structure called the cochlea, because it is shaped something like a snail shell. The marvel of hearing is perhaps less appreciated than that of seeing; actually, the ear is capable of extremely fine discriminations of pitch, intensity, and timbre or quality, and in some ways surpasses the eye.”[151]  


5. Sight


The two superior external senses are sight and hearing because of their proximity to reason, that is, they are more cognitional in character than the other external senses. Sight is the external sense which responds to the stimuli of light. The organ of sight is the eye, whose seat of vision is the retina, and its receptors being its rods and cones. Sight’s proper sensible object is color, which is light as reflected or refracted by a surface. Color is usually divided into chromatic (the colors of the spectrum) and achromatic (the black-grey-white tones). Let us take an example, namely, a boy looking at a mango. The external sense involved here is sight (or vision). The perceptual object is the mango but the proper object of sight is the color of the fruit. The informational medium would be the reflected light from the mango’s surface (visible electromagnetic waves). The proximal stimulation involves photon absorption in the rod and cone cells of the retina, the receptor surface in the back of the eye.  


The Object of the Senses


A sense is an organic cognitive power, operating by means of a sense-organ, which enables the sentient being to directly perceive and know a certain kind of corporeal object. A sensible is that object which in any way can be appehended by a sense. The object of an external sense is called an external sensible, which is divided into essential or per se sensibles and accidental (per accidens) sensibles, according as to whether they are sensible in themselves or not. For example, Bob’s color and size are essential sensibles, while Bob himself, though being an individual substance of a rational nature, is an accidental sensible.


Proper Sensibles


A proper sensible is that essential sensible which directly refers to only one sense. For example, the color red of a rose is the proper sensible of the external sense of sight. Epistemologists usually call this kind of sensible a secondary sense quality. Colored objects are sensed as colored by the sense of sight alone and not by any other sense. Now, that which is sensed by one sense alone constitutes the proper object of that sense. Color in its concrete being as a quality of a corporeal thing, that is, color as extended or a colored surface, is the proper object of sight and no other.

Are proper sensibles truly objective? What is their status as regards their objectivity? Mechanists, in general, maintain the subjectivity of secondary sense qualities (the proper sensibles). For them, only the common sensibles (the primary sensibles) could be considered as trans-subjective. They believe that color, warmth, flavor, etc. are purely subjective modifications of the sentient subject and that what is truly trans-subjective is movement (a common sensible), which would produce the illusion of the different qualities. Against this position Llano maintains that “such affirmations are not scientific but philosophical and, in this case, they are unfounded. Classical mechanics could, by a homogenizing abstraction, take notice only of movement; but it is not methodologically permitted to reduce the real merely to movement, as the further development of physics has demonstrated by depriving mechanistic reductionism of its supposedly scientific foundation…St. Thomas, commenting on Aristotle, maintains – against subjectivist positions – that ‘movement according to quantity is not the same thing as movement according to quality or form. And even if it be granted that things are in continuous movement according to quantity, and that all things are always invisibly in movement in this way, nonetheless, according to quality or form not everything is always moving. And thus there can be definite knowledge of things, because things are known more by their species or form than by their quantity.’[152] Things really have qualities which inhere in them as accidents and which we perceive in an immaterial way, in accordance with the formal object and the range of each sense faculty, but not arbitrarily, and always with an objective aspect. We perceive the qualities of things – some, not all of them – immediately, because they are what primarily and properly affects our sense organs; by means of these qualities we grasp quantities concomitantly and immediately, but indirectly.

“The denial of the extra-subjective scope of our knowledge of qualities completely compromises gnoseological realism since intellectual knowledge starts, in the final analysis, from the grasping of proper sensibles. In sense knowledge there is stability and in it there is no contradiction. For example, a thing never seems sweet and bitter at the same time; and of itself, sweetness is always the same thing. What can happen – without this being a denial of the reality of sense knowledge – is that, because of the deficiencies of our organic constitution, we do not perceive something properly at a given moment.

“The external senses immediately know their object as something trans-subjective: this is unquestionably evident. Immediately, and without hesitation, we know that the known is something real and distinct from our knowledge. External sense knowledge is the intuition of an object which is physically present, without the mediation of an expressed species. Like all knowing faculties, the external senses are active; however they are not productive of their objects but – in this respect – receptive: they produce their object neither according to its matter nor according to its form, nor according to its presence (as the different idealisms would have us believe), but rather know their object in its objective reality. They produce only their own proper cognitive action, which is a praxis by which they attain their proper object. And this complete trans-subjectivity of sense objects is not only apparent, but real, true.[153][154]   

Going beyond the mechanists, the idealists declared the common sensibles (the primary sensibles) to be likewise subjective. Against these positions we find realism, which maintains that not only are common sensibles objectively real but also the proper sensibles. Adopting a moderated perceptionism against the interpretationism of classical and modern mechanism (which denies the objectivity of the proper sensibles), Sanguineti explains that “sensible qualities not only manifest themselves as objective, but have an operativity independent from their activity on the sentient: heat dilates bodies, light has concrete effects on material beings, and the same can be said of sound, the aroma of flowers, etc…we perceive objective qualities in normal cases and according to certain conditions of observation…The reduction to pure quantity (to the sensible communes) has not been able to ever cancel some qualitative elements, such as force, resistance, causal influence, etc., which are invariably encountered in the most mechanical scientific explanations (these in particular have recourse frequently to certain tangible qualities).”[155]      


Common Sensibles


Common sensibles are essential sense objects which can be sensed by more than one sense. For example, the size of a particular corporeal being, say a rock, can be sensed by both the external senses of sight and touch. The common sensibles are also called primary sense qualities. Though sensed in themselves, common sensibles (e.g., size, movement, shape) are not sensed immediately but by means of a proper sensible. For example, an apple’s figure is seen by means of its color and may be felt by means of its pressure and temperature, which are the proper sensibles of the external senses of sight and touch (also called the somesthetic sense). There are five common sensibles, namely, size, shape, number, motion and rest. All these common sensibles, says Aquinas, are reducible to quantity, which is the proximate subject of the qualities (proper sensibles) that cause alteration in the sense. Therefore, the common sensibles do not move the senses directly but by reason of a proper sensible. Aquinas writes: “The common sensibles are reducible to quantity. As to size and number, it is clear that they are species of quantity. Shape is a quality about quantity, since the nature of shape consists in fixing the bounds of magnitude. Movement and rest are sensed according as the subject is affected in one or more ways in the magnitude of the subject or of its local distance, as in the movement of growth or of locomotion, or again, according as it is affected in some sensible qualities, as in the movement of alteration; and thus to sense movement and rest is, in a way, to sense one thing and many. Now quantity is the proximate subject of the qualities that cause alteration (proper sensibles) as surface is of color. Therefore, the common sensibles do not move the senses first and of their own nature, but by reason of sensible quality; as the surface by reason of color. Yet, they are not accidental sensibles, for they produce a certain diversity in the mutation of the sense. For sense is changed differently by a large and by a small surface.”[156]  

Brennan explains that “every object that falls under the senses is quantified and localized by the laws of its cosmic being. It has definite spatial and temporal dimensions. It always exists and operates somewhere and sometime. Now, these very facts immediately surround it with characteristics that are not entirely explicated in terms of colors, sounds, odors, flavors, and tangible properties. A rose, for example, is not merely red and fragrant; it also has surface qualities, extension, shape, solidity, a measurable distance away from the eye, a definite size, perhaps even a local motion as it sways in the breeze. A song, for instance, is not merely a series of auditory stimuli. It also has a definite tempo, a meter, a distribution of accents, and a rhythm. Quite obviously, none of the spatial features of the rose, and none of the temporal characteristics of the song, are perceived by any one outer sense alone, in the same way that color is seen by the eye or sound is heard by the ear. Rather, they are aspects of the material object that simultaneously appeal to several external senses, representing an association of data that require the combined efforts of many senses if they are to be perceived. Aquinas, therefore, following the lead of Aristotle, calls them common sensibles.”[157]

What is the phenomenology of our knowledge of the common sensibles, that is, how do we grasp common sensibles like size, shape or figure, and movement by means of our external and internal senses, as well as by our intelligence? Sanguineti observes that “the external senses perceive the extended character of bodies, which is not a subjective form, but a real property of material beings. Nonetheless, dimensions are perceived not in an absolute way, but rather from a certain point of view, depending on the situation of the observer: each person sees extension in a different way from another, and also differently according to the variations of his position. We do not for this reason think that the dimensions change, or that they are subjective: it is precisely the integral experience, particularly thanks to the contribution of the internal senses, such as common sense, imagination and memory, which allows a more complete perception of things, surpassing the limitation of the external senses. For example, we see a person far away, but we do not think the person is small; we see the sun, and since we are lacking a greater experience, it seems to us that the sun is larger than the stars.

“Sensible knowledge is imperfect, gradual, and fragmentary: it is necessary to find some constant, determined relations between the data of the senses. Therefore, perception develops itself in a partially constructive way (that is to say, it is not purely passive), where one seeks to objectivize in agreement with reality. For example, think of the effort that a man blind from birth must make to ‘construct’ his image of the world with the few elements of the world he possesses. In general, the normal adult has a sufficient experience for the most immediate world, while for the macrophysical and microphysical sphere ordinary experience is clearly insufficient, occasioning errors that only a greater experience can correct.

“Now, if in knowledge there is construction (not a priori, but following the indications of immediate experience), precisely for this reason there exists the possibility of error. Man organizes the spatial structures of the surrounding world according to some schemes that are later corrected, and which can sometimes occasion errors, such as, for example, in not noticing the small differences between the objects, or not foreseeing possible anomalies in things that we imagine to be normal. Thus we cannot see bodies from all sides, but the imagination supplies with the help of past experience, even if this does lead to a greater risk of error.”[158]   


Sensibles Per Accidens


A sensible per accidens (or accidental sensible), also called an incidental sensible, is not in itself the object of an external sense, but is apprehended by another cognitive power or faculty as accompanying that which a particular external sense grasps. For example, the bodily substance of a red apple is an accidental sensible or accidental sense object of the sense of sight, because the intellect apprehends it as the subject of the red-colored sphere. The red apple, then, is a sensible per accidens by reason of its color and size. The senses cannot grasp the nature or essence of the substance or thing; this is done, instead, in the realm of intellectual knowledge.   


Errors of the Senses


Error, in the strict sense, is the affirmation of the true of what is false. It is a judgment which fails to correspond to reality, to what is. But what about the so-called errors of the senses which the skeptics bring up so as to discredit realism and objective evidence? Gilson responds, writing in Methodical Realism that “we must not allow ourselves to be impressed by the famous ‘errors of the senses’ nor be astonished by the enormous propaganda which idealists make of these errors. These are people for whom the normal cannot be anything more than a special case of the pathological (…). Therefore we must consider as errors of the same sort the arguments which the idealists borrow from the skeptics about dreams, hallucinations of the senses and madness. There are, it is true, visual errors; but this proves, above all, that not all our visual perceptions are illusions. When someone dreams he does not feel different from when he is awake, but when he is awake he knows himself to be totally different from when he is dreaming; he even knows that he cannot have what are called hallucinations without beforehand having had sensations, just as he knows that he would never dream anything without having beforehand been awake (…). The reason why these things are so upsetting to the idealist is that he does not know how to prove that they are illusions; but there is no reason why they should upset a realist for whom only illusions are really illusions.”[159] 

In normal persons, sense knowledge functions properly – providing truthful, objective knowledge of trans-subjective reality. Occasionally, however, the senses can accidentally make mistakes with regard to the common sensibles. Thus, one can sometimes make a mistake with regard to the actual height of a certain object when viewed from a distance or angle. Mistakes concerning the proper sensibles are usually the result of some organic malfunction of the senses. Thus, for a certain person striken with a high fever, certain sweet foods may taste bitter, for his illness has affected his taste buds. But this is not the normal functioning of the sense of taste and therefore, such a situation can only be described as accidental and not ordinary. “Errors and illusions of perception, sensorial defects, hallucinations, the confusion of sleep with wakefulness, etc., are an indirect confirmation of realism. They show the distinction between truth and error, and the possibility that the subject, through illness or other causes, may not conform himself to what is real. A proof of this is that man can recognize these deficiencies: on correcting an error, what is real is manifested as such, as explicitly different from appearances.”[160] Therefore, “the senses judge naturally about certain objects, as occurs with proper sensibles; with other objects the judgment happens by way of a certain comparison which is carried out in man by the cogitative faculty, which is a sense faculty comparable to the estimative sense in animals; and it is thus that the senses judge about common and indirect sensibles. The natural operation of a thing is always uniform unless it is directly impeded either by an intrinsic defect or by an extrinsic obstacle, so the judgment of the senses is always true about proper sensibles, unless there is some impediment in the organ or in the medium; but about the common and indirect sensibles the judgment of the senses is, at times, false.”[161]


B. The Internal Senses


Internal experience reveals that we do not just possess external senses that respond to their proper sense objects (like color, sound, flavor, etc.), but we also have internal sense powers as well. For example, I do not merely see the color red of a rose, or just smell its fragrance, but I also, at the same time, am aware of, am sense conscious of, the fragrant red-colored rose before me. I am also aware that I do not just see the rose or smell its fragrance, or feel its smooth petals, all in isolation from each other, but am also aware of my ability to distinguish sensitively between seeing the rose, smelling its fragrance, and touching its soft petals. I am also aware that I have the power to synthesize (or combine) these various sensations of the external senses into a perceptual whole. I also have the power to form images of things in my mind even in the absence of those things in extra-mental reality. I have the power to remember past sense experiences as past, and so forth. That these cognitive actions remain on the level of sense knowledge is attested to by the fact that the higher animals, by their behavior, are capable of such activity. On this point, Bittle writes that the distinction between, and synthesis of, sensations and their objects pertains to the level of sense operations and not intellectual operations, “is shown by the fact that brutes also possess this ability. Consider the actions of a dog. Suppose the dog is in one room, and his master is in the adjoining room behind the closed door. If the master calls the dog by name, the dog will prick up his ears and listen; he recognizes his master’s voice. Not seeing his master, he runs about; coming to the door, he sniffs and recognizes the odor peculiar to his master. If the master now opens the door, the dog runs to him without hesitation, even if other persons are also present. The dog knows that he hears his master, but he also knows that he does not see him; he recognizes the fact that the sound and odor are those of his master, but he also knows that he lacks the sight of his master; and when he sees him, he combines sound and odor and sight and refers them to the same object, his master. The dog, therefore, makes a concrete distinction between the various sensations and their objects and synthesizes them into a concrete whole.”[162]      

The internal senses are called internal because they have no external organs receptive of direct impressions from extra-mental reality but instead receive their data from the external senses by means of their respective organs. An internal sense is defined as a cognitive sense power which acts in dependence upon the action of the external senses. There are four internal senses, namely, common sense (sensus communis, also known as the central sense), imagination, memory, and the estimative (which is the cogitative in man).


1. Common Sense (Sensus Communis) or Central Sense


Common sense[163] (sensus communis) is the first our internal senses. Because of the equivocation it might produce it would be better to use the term “central sense” to refer to our internal sense at hand. For the ordinary man in the street “common sense” would refer to the common agreement of mankind upon a certain issue or issues, or it could refer to sound practical judgment, a sort of good “horse sense”. Some refer to “common sense” as certain intuitive judgments concerning certain fundamental principles. This is not our internal sense faculty or power in question at all. Some philosophical anthropologists like R. E. Brennan in his General Psychology would rather use the Latin “sensus communis” to refer to this internal sense, but for those well versed in Latin, “sensus communis” has just as many meanings in the Latin as in the English. Some psychologists would prefer to use the term “synthetic sense” but the term is not broad enough to include all the functions of this faculty, which includes the operation of distinguishing, as we shall see. George Klubertanz uses the term “unifying sense,”[164] but again the term is not sufficiently broad enough to encompass all the functions of our internal sense power in question.     


Central Sense Defined


What then is this internal sense, called “common sense” by classical philosophical psychology and “central sense” by modern cognitive psychology and a number of realist and scholastic philosophical psychologists? It is defined as the internal sense power that consciously perceives, distinguishes and synthesizes the objects and operations of the presently active external senses. It is “the power by which we know that we are actually sensing, and because it is one power which has as its object all our sensations, and the acts of the sensibles as identical with sensation, it is that by which we unify and combine our acts of external sensation into one experience, and compare and contrast these sensations and their objects among themselves.”[165] We have “a power which connects and correlates the objects that differ among themselves, joining them in a psychical unity which corresponds to the physical unity that things have in nature. Evidently it cannot be a question here of a kind of discourse, which belongs only to the power of reason. Even in the sense order man knows things as wholes. A unified object is the object known by the central sense. By its detailed study of sensory experience, Gestalt psychology has given us empirical evidence of the operation of such a power, and has, in this respect, reiterated a very important conclusion of Aristotelian and Thomistic psychology. Gestalt psychology has shown that our sense-knowing entails a synthesis of specifically diverse sensations.”[166]


Objective and Subjective Phases


The central sense has a double function which correspond to an objective phase and a subjective phase. In the objective phase, when the external senses react to a stimuli the central sense perceives and distinguishes between the various sensible qualities presented and combines them and refers them to a single object whence originate the said stimuli.  

Individual external senses give us only their proper objects. Sight’s proper object, for example, is colour, which is light reflected or refracted on a surface. Smell’s proper object is odour. Now, it is impossible for the sense of sight not just to see, but also to smell odour, hear sounds, etc. The sense of smell, likewise, cannot see colours and hear sounds at the same time it takes in various odors. The various external senses cannot of themselves combine or integrate into unified whole objects the various sense impressions that they receive for each external sense organ can only receive its particular kind of sense impression. But we are able to see, smell, touch and taste perceptual wholes at the same time like pizzas, fried chicken and soup, so what power accounts for this perceptual unity? It is none other than the central sense, the internal sense power that does this work of organization and synthesis. This description shows why our internal sense should be called the “central sense” and not merely the “synthetic sense,” since this faculty not only combines or synthesizes the different external sensations in order to produce a perceptual whole, but also has the task of discriminating, of distinguishing, among the various objects of the external senses. 

The central sense also has a subjective phase to its function, namely, sense awareness or sensory consciousness. By means of the central sense, man and the higher animals become aware of the acts of sensation present in the various external senses, such as the act of hearing, seeing, smelling, etc. By means of the central sense one also becomes aware of the differences between the acts of sensation, so that man and the higher animals are sensorily aware, for example, that the act of seeing is not the act of hearing, and that the act of smelling is not the act of touching, and so forth.  


Central Sense and Common Sensibles


Gardeil, like Aristotle, notes a third function of the central sense, namely, the perception of the common sensibles in conjunction with the external senses.[167] This, of course, does not mean, cautions Gardeil, that the common sensibles are the proper objects of the central sense in the manner that the proper sensibles are the proper objects of the external senses.[168] Reith observes that “because of the close association in name between common sensible objects and the central sense (sensus communis), it was thought by some that the five common sensibles (movement, rest, number figure and magnitude) are properly the objects of this power. It is true that the central sense perceives the common sensibles, but only because it perceives all the objects of the external senses. Since the common sensibles are properties of objects as they exist in nature, if they are known at all, it is by means of the external senses. Extension is not perceived by the central sense unless it is first sensed by the external senses. For if the eye or the hand, for example, did not grasp the extension of a body, it would be impossible for the central sense to perceive extension. Hence the common sensibles are not properly the objects of the central sense.”[169]


Organic Sense Power


We know that the central sense is an organic sense power or faculty for it is concerned with sense objects and besides, the higher animals possess this power yet are devoid of intellectual and abstractive reasoning. The central sense is also the root and principle of the external senses; the external senses are merely instrumental causes which serve the central sense (which acts as a primary or principal cause).   




The stimuli of the external senses, organized and synthesized into a perceptual whole by the central sense, is our percept, the sensory representation of the object as it appears to the activated external senses and the internal central sense. In Scholastic teminology the percept is called the impressed species of a sensible order. The impressed species is the form of the object in intentional mode, existing in a cognitive power without the subjective conditions of matter. “The impressed species,” writes Reith, “can be called a ‘representation’ of the external object, if we take this word in its basic meaning, that is, it makes present again to the knower what is present in the object. It would be incorrect to say that the impressed species is a representation as a painting or photograph is. A photograph is an entitative being, and it has not an identity with but only a similarity to the thing it represents. But the impressed species is the same form as that in the physical world – the same color, shape, hardness or heat – but differing in its immaterial mode of existence. The impressed species, however, is not formal knowledge of the thing, but a principle for acquiring knowledge of the thing which it represents. It is called a ‘virtual likeness.’

“It is essential to a realistic epistemology that the impressed species be understood as instrumental to knowledge rather than as the object of knowledge. When we see something, for example, we do not see impressed species but the object itself. This conclusion is paradoxical, since we hold that the form is present in the knower not in its mode of physical existence but in its intentional existence; yet we hold that we know objective reality. On the explanation of this difficulty hinges the only satisfactory solution to the problem of knowledge. For if we say that through the senses we know an image and not reality, we shall have no certitude that our sensations correspond with reality.

“It is not enough to say that we know the external world through an application of the universal principle that causes produce similar effects. Nor can we solve the problem on the basis of faith in our powers of knowledge or in the veracity of God Who made them. An application of the principle of causality is not enough, for even though every effect is like its cause, this need not be a formal likeness. Furthermore, the principle of causality itself cannot be known unless we have a prior certitude about our sense knowledge. And the same necessity holds for any kind of act of faith. The view that our sense powers must be reliable because God could not deceive us when He gave us these powers suffers from the fallacy of circular argumentation, since God’s existence is known through the use that reason makes of our sensory powers.

“The sensible form has a twofold mode of existence which we can compare to the two sides of a tapestry. In a tapestry it is the very same stitching which is on the front and the back. The same thread and the same color are present on both sides. The back of the tapestry is comparable to the sensible form that exists in a physical way and the front of the tapestry to sensible form existing in an intentional way (the impressed species). Just as the form appears only on the front of the tapestry, so sensation takes place only in the union of the sense with an intentional form.

“It is most important to stress the identity of the physical sensible form and the intentional form. Actually they are one and the same in a twofold perspective, the one material and the other immaterial…

“Besides being an intentional or representative form, the impressed species is also an accidental form existing subjectively in the power of knowledge. It belongs to the category of quality, as a disposition that modifies the power.[170] All immanent acts, concepts and impressed species belong in the first species of quality as dispositions, because they dispose the power well or ill in respect to its object. Since it is an accidental quality, the sensory species must inhere in a subject; however, this union is not the essence of knowledge but concomitant with it. The intentional form by which the knower is identified with the object known does not belong to any particular category insofar as it is representational, for it is identical with whatever category or mode of being it represents. It is this psychological entitative existence of the species that puts us in contact with the intentional existence in which knowledge consists.

“In concluding the comparison of the two modes of existence, we should say that the intentional and the entitative existence of the impressed species, while inseparable in the knower, must be sharply differentiated if knowledge is really a nonsubjective union of the knower and the thing known.”[171]


2. Imagination


Imagination is the internal sense power or potency which is capable of forming and retaining images (or phantasms) of things we have seen before even in the absence of the things in reality that once actuated our external sense organs. Its specific functions are threefold: 1. it forms and conserves images; 2. it is capable of reproducing the images even in the absence of the perceived object; and 3. it also has the power to fashion and construct images or phantasms into new combinations (as is seen in pictorial, music and literary creations).

The imagination is different from an external sense for the latter cannot retain the impression of the thing sensed by it when the sense object is no longer acting upon the external sense organ. For example, my eyes cannot see a squirrel that has hid itself behind a tree.

We do indeed have the faculty of preserving sensible impressions produced in our consciousness and of representing them, in the absence of the objects which produced these impressions, by means of images. We have many types of imagination. We have what is called visual imagination (which is the power to recall how a person, thing or place looks like), auditory imagination (the power to recall various sounds, like running Beethoven’s Moonlight Sonata in our heads), and also the power to imagine how things felt (by means of a touch image), tasted (by means of a gustatory image), and smelt (by means of a olfactory image). We also have what is called creative or constructive imagination, where we combine into one image the various sense impressions which were not actually perceived together, thus creating in one’s mind an ‘imaginary’ being.

The percept or impressed species of a sensible order provides the stimulus for the imagination; the impressed species (the percept) is received by the actuated imagination, whose product is the image or phantasm (which is called the expressed species of a sensible order).

There are a number of differences between the impressed species of sense knowing (our percept) and the expressed species of sense knowing (our image or phantasm). Percepts are vivid and strong, while images or phantasms are pale and weak. Consider, for example, our perception of the book before us as it exists in extra-mental reality; our perception of it is undoubtedly strong and vivid. Now close our eyes and imagine that same book; the image that is before us (which is not abstract and universal but particular and individual) is obviously pale and weak in comparison with the percept. Another difference between percepts and images: percepts cannot be changed by the power of our will, whereas images produced by the imagination can; we cannot alter the perception of the book before us by sheer will power, whereas our image or phantasm of that book can be modified as suits our fancy (in creative or constructive imagination). The same goes with sound percepts and auditory images, taste percepts and gustatory images, touch percepts and tactile images, smell percepts and olfactory images.

Such differences manifest the difference between our central sense (the sensus communis) and our imagination: “The central sense receives its data from the external senses and is directly dependent on the stimulation of these senses in its own proper function; hence, it never operates except when the external senses function, and it occupies itself exclusively with the objects presented by these senses. The imagination receives its data from the central or synthetic sense and then forms phantasms of the objects, and these phantasms can be revived even when the originals, the objects, are absent; the imagination, therefore, does not occupy itself with the objects, but with the images in so far as they are representations of these objects. The causes which produce the percepts exist outside of us, as a rule, and are beyond our control; but the causes which produce the phantasms exist entirely within us and are, to a great extent, subject to our control. Because of these conditions, the percepts come into existence as items in a series fixed according to time and place, following the spatio-temporal order of the physical stimuli; but the representations of the imagination, being derived from the stored-up images always present after their formation, are capable of being evoked, separated, or combined in various ways and can be arranged in a series totally different from that in which the original perceptions occurred. The products of the central or synthetic sense are presentations of immediately present objects; the products of the imagination are re-presentations of these objects in the form of phantasms.”[172]      

The imagination is different from the central sense for the latter internal sense is directly dependent upon the sensations of the external senses and is in operation only when the external senses sense an object, while the former internal sense can operate and produce images of sense objects even in the absence of those objects in extra-mental reality which provide the stimuli for the sense organs. Therefore, the proper object of the latter is the actual sensation of the external senses, while the imagination abstracts from the actual presence of the sense objects. Since a difference in proper objects implies a real distinction of cognitive powers, imagination, therefore, is really distinct from the central sense. 


3. Memory


This internal sense faculty is like imagination in that it can form images of things even in the absence of the thing existing in extra-mental reality. But the mere retention and reproduction of images are more the function of imagination than memory; what is distinctive of memory is the recognition of past objects and events, not the former, namely the retention and reproduction of phantasms or images. Memory, therefore, goes further than imagination in that it puts our image of a thing in a definite past experience. In imagination I, for example, can picture in my mind my dog Snoopy; I can form an image of my dog within me. In memory, instead, not only do I picture Snoopy, but I can remember when he bit me on March 25, three years ago on a rainy day. To remember something is to picture something as I actually experienced it on a definite past occasion, so that the occasion and the experience are as much a part of the memory as is the thing itself. Consequently, memory is defined as the internal sense faculty or power that enables the sentient being to recall past things and conscious states and to recognize them as having been present in past experiences.

There are a number of differences between imagination and memory: “The chief features in which remembrance differs from mere revival of images,” says Maher, “are: 1. The freedom of the imagination as to the number and variety of its acts, the limited character of our recollections; 2. The casual and variable order of the former states, the serial fixity and regularity of the latter; 3. The isolated nature of imaginary events, the solidarity or relatedness of remembered occurrences, which are inextricably interwoven with multitudes of other representations; 4. Finally, the peculiar reference to my own actual experience involved in the act of identification or recognition, which forms part of the recollection but is absent from the creations of fancy.”[173] Nevertheless, there is a close connection between reproductive imagination and memory; the former supplies the image of a past experience, and the latter recognizes that image as a representation of a past experience. There are two main features of memorial activity, namely, the recognition of the past and the estimation or measurement of the past. [174]   

Memory and the Brain. Where in the brain are our memories stored and what structures and areas of the brain are involved in memory processes, such as the encoding of data as well as its retrieval? Many of the specific structures of the brain have been located. Various neurologists and cognitive psychologists have maintained that the subcortical structures involved in memory include the hippocampus, the thalamus, the hypothalamus, the basal ganglia (collections of nucei and neural fibers in the forebrain region) and the cerebellum (for classically conditioned responses and to various cognitive tasks in general). Others (e.g., Zola, Squire) have argued that the cerebral cortex appears to be involved in long-term memory storage. They hold that visual, spatial and olfactory properties of an experience could be stored in each of the areas of the cerebral cortex responsible for processing each type of sensation. Scientists (e.g., Squire) have also presented studies showing that the neurotransmitters serotonin and acetylcholine are essential to the functioning of memory.  


4. Estimative (in Animals and Cogitative in Man)


The estimative internal sense,[175] commonly called instinct, is defined as an internal sense cognitive power which enables the sentient being to provide for its physical well being by judging the harm or benefit to be found in objects of the sensory order. The faculty’s goal is the preservation of the sentient being’s existence. The other sense potencies are subordinated to this power for the estimative employs the particular acts and objects of the other sense faculties in view of the common end of the development and preservation of the sentient being’s existence.

The higher sentient animals, and also man, perceive things not merely as objects having certain sensible qualities, but also as being good or bad, desirable or repugnant, and useful or harmful to one’s own being. An antelope, for example, perceives a lion in the distance not only as a thing having certain sensible determinations of colour, odor, size, etc., but also something dangerous to itself, a veritable enemy to its well-being, and without having to be taught, speedily runs away. Such dangerousness is not a sensible quality which any external sense organ can perceive, yet we observe animals with that ability to perceive things under such non-sensible aspects. These non-sensible aspects are aspects of individual sensible bodies not perceivable by the external senses, yet grasped by the sentient animal or human person in the total perceptive act. The internal sense power that does this is called the estimative in animals and the cogitative in humans.

The cogitative is different from the estimative in that man can regulate and direct his instinct through the power of reason, while animals cannot. “Because man has a sensory nature with the same basic tendencies of self-preservation and reproduction found in other animals, he has a sense power which corresponds to the estimative sense in irrational animals. But because his sensory powers operate in conjunction with, and in subordination to, reason, this power cannot be identical with that of irrational animals. In man the knowledge of what is harmful or helpful among sensory objects is tempered and directed by reason. The material objects of the cogitative sense, while differing in no essential way from the material objects of the estimative power, have an excellence in proportion to the goal which they serve. Man’s knowledge of self-preservation, the variety of his food and the variety of ways in which he prepares it, his manner of expressing sexual love, and so on, are examples of cogitative actions. These are examples of the types of good that belong to man’s sensory nature, but raised to a superior order by the direction of his reason. In order to acquire the ‘particular experiences,’ in the sense in which St. Thomas uses the term, not only reason must be employed, but the cogitative power also, since it is directly concerned in the knowledge of the singular, whether it be an individual of some species, or a particular human action. In man the cogitative power operates as an instrument of his intellect, both in acquiring knowledge, and in directing his actions.”[176]






[1] “Science” here is to be understood, not in a reductivist sense referring only to the positive particular sciences (e.g., biology, chemistry, physics), but in the analogous general sense of “certain knowledge through causes”(ARISTOTLE, Posterior Analytics, I, 2, 71 b 9).

[2] Etymologically, philosophy means “love of wisdom,” while its perennial real definition is: “the science of all reality in its ultimate causes and first principles, studied using the light of natural reason.” 

[3] Paul Glenn explains that “the object of a science is its scope, its field of investigation, its subject matter. Further, it is the special way in which it does its work in its field, or it is the special purpose which guides it in its work. Thus the object of any science is two-fold. The subject-matter, the field of inquiry, is the material object of the science. The special way, or purpose, or end-in-view, which a science has in dealing with its subject-matter or material object is the formal object of that science. Many sciences may have the same material object, for many more or less independent inquiries may be prosecuted in the same general field. But each science has its own distinct and distinctive formal object which it shares completely with no other science. That is why this object is called formal; it gives formal character to the science; it makes the science just what it is formally or as such. To illustrate all this. Many sciences deal with the earth under one aspect or another. Such, for example, are geology, geodisy, geography, geonomy, geogony, and even geometry. All these sciences study the earth; they have therefore the same material object. But no two of these sciences study the earth in the same special way or with the same special purpose. Geology studies the earth in its rock formations; geodisy studies the earth in its contours; geography studies the earth in its natural or artificial partitions; geonomy studies the earth as subject to certain physical laws; geogeny studies the earth to discover its origins; geometry in its first form was a study of the earth in its mensurable bulk and its mensurable movements. Thus, while all these sciences have the same material object, each of them has its own formal object. If two sciences were to have the one identical formal object, they would not really be two sciences at all, but one science. It is manifest that a science is formally constituted in its special character by its formal object; it is equally manifest that a science is distinguished from all other sciences by its formal object”(P. GLENN, Theodicy, B. Herder, St. Louis, 1950, pp. 4-5). In sum, the material object is the subject matter, while the formal object is the special way in which that subject matter is studied.

[4] G. ZAMBONI, Introduzione al corso di gnoseologia pura, Milan, 1924.

[5] S. VANNI ROVIGHI, Gnoseologia, Morcelliana, Brescia, 1963.

[6] The first operation of the mind is simple apprehension, while the second is judgment.

[7] Bittle gives us the following example of induction: “‘Water, anywhere on land or sea, when at sea level, freezes in every instance at +32° F.; But water anywhere on land or sea is all water; Ergo, all water freezes at sea level at +32° F.’ Of course, no attempt has ever been made to freeze water at every spot on the globe which is at sea level; but since, whenever and wherever done, water always froze, it is rightly concluded that freezing is a property necessarily connected with the essence of water and has, therefore, the value of a universal law applicable to all water.”(C. BITTLE, The Science of Correct Thinking, Bruce, Milwaukee, 1953, p. 176).

[8] Bittle gives us this example of deduction: “Suppose there is a doubt in our mind whether the mimosa pudica, due to its peculiar reaction to the touching of its leaves, possesses sentiency or no sentiency. And then suppose that science has definitely established the law that the nature of a plant is devoid of sentiency. We can now proceed with the following mediate inference: ‘All plants are devoid of sentiency; But the mimosa pudica is a plant; Ergo, the mimosa pudica is devoid of sentiency.’ This is a case of deduction. From the general law that ‘All plants are devoid of sentiency’ we conclude that the ‘mimosa pudica,’ because it is one of the class of ‘plants,’ must fall under the general law governing ‘all plants,’ and therefore ‘the mimosa pudica is also devoid of sentiency.’”(C. BITTLE, op. cit., pp.175-176).

[9] Studies on the method utilized in philosophy of knowledge: R. J. HENLE, Method in Metaphysics, Marquette University Press, Milwaukee, 1951 ; J. M. ALEJANDRO, El problema del método en la investigación gnoseologica, “Pensamiento,” 13 (1957), pp. 39-40 ; E. GILSON, Thomist Realism and the Critique of Knowledge, Ignatius Press, San Francisco, 1986 ; E. GILSON, Methodical Realism, Christendom Press, Front Royal, VA, 1990.

[10] F. MORANDINI, Critica, Gregorian University Press, Rome, 1963, p. 33.

[11] J. J. SANGUINETI, Logic and Gnoseology, Urbaniana University Press, Rome, 1988, p. 131.

[12] A. MILLAN-PUELLES, Fundamentos de Filosofía, Rialp, Madrid, 1976, p. 457.

[13] F. J. THONNARD, A Short History of Philosophy, vol. 1, Desclée, Tournai, 1956, p. 16.  

[14] Studies on the epistemology of Parmenides: G. VLASTOS, Parmenides’ Theory of Knowledge, “Transactions of the American Philological Association,” 77 (1946), pp. 66-77 ; E. D. PHILLIPS, Parmenides on Thought and Being, “Philosophical Review,” 64 (1955), pp. 546-560.   

[15] J. MARITAIN, An Introduction to Philosophy, Sheed and Ward, 1979, pp. 45-46.

[16] J. MARITAIN,  op. cit., p. 46.

[17] F. J. THONNARD, op. cit., p. 22. 

[18] G. REALE, op. cit., p. 149.

[19] PLATO, Sophist, 231 D-E; 79. A. 2 D-K 2:252-53.

[20] XENOPHON, Memorabilia, I.6.13; LCL 73; 79.A.2a D-K 2:253.

[21] XENOPHON, Cynegeticus, 13.8; 79.A.2a D-K 2:253.

[22] ARISTOTLE, Sophistical Refutations, 1.165a21; 79.A.3 D-K 2:253.

[23] R. DESCARTES, Discourse on Method, 6.

[24] De Veritate, q. 2, a. 2. 

[25] Gregory the Great, as quoted by Thomas in the passage just cited.

[26] J. PIEPER, Leisure the Basis of Culture, St. Augustine’s Press, South Bend, IN, 1998, pp. 78-79.

[27] J. MARITAIN, op. cit., p. 49.

[28] DK 80 B 1. Cf. SEXTUS EMPIRICUS, Adv. Math., 7.60; LCL 2:31-33; PLATO, Theaetetus 151E-152A; 80.B. D-K 2:262 ; DIOGENES LAERTIUS, Lives, 9.51 ; LCL 2:463, 465; 80.A.1 D-K 2:253-55.

[29] G. REALE, op. cit., p. 157.

[30] Cf. ARISTOTLE, Metaphysics, K6. 1062b 13ff; 80.A.19 D-K 2:259. 

[31] SEXTUS EMPIRICUS, Outlines of Pyrrhonism, 1.216; LCL 1:131; 80.A.14 D-K 2:258.

[32] Cf. DIOGENES LAERTIUS, Lives, 9:51; LCL 2: 463, 465; 80.B.4 D-K 2:265.

[33] DK 82 B 3.

[34] P. GLENN, Criteriology, B. Herder, St. Louis, 1941, pp. 180-183.

[35] J. MARITAIN, op. cit., p. 57. 

[36] ST. THOMAS AQUINAS, In I Perih., lecture 10.

[37] J. J. SANGUINETI, Logic, Sinag-Tala, Manila, 1992, pp. 41-42.

[38] C. BITTLE, The Whole Man, Bruce, Milwaukee, 1956, p. 304.

[39] Studies on the principle of non-contradiction: R. GARRIGOU-LAGRANGE, Le sens commun, la philosophie de l’être et les formules dogmatiques, Beauchesne, Paris, 1909 ; J. H. NICOLAS, L’intuition de l’être et le premier principe, “Revue Thomiste,” 47 (1947), pp. 113-134 ; A. MARCHESI, Il principio di non contraddizione in Aristotele e in Kant e la funzione del “tempo,” “Rivista di filosofia neo-scolastica,” 52 (1960), pp. 416-421 ; L. ELDERS, Le premier principe de la vie intellective, “Revue Thomiste,” 62 (1962), pp. 571-586 ; E. BERTI, Il principio di non contraddizione come criterio supremo di significanza nella metafisica aristotelica, Accademia Nazionale dei Lincei, Rome, 1967 ; E. BERTI, Il valore “teologico” del principio di non contraddizione nella metafisica aristotelica, “Rivista di filosofia neo-scolastica,” 60 (1968), pp. 1-24 ; E. BERTI, Sulla formulazione aristotelica del principio di non contraddizione, “Rivista di filosofia neo-scolastica,” 61 (1969), pp. 9-16 ; P. C. COURTÈS, Cohérence de lêtre et Premiere Principe selon Saint Thomas d’Aquin, “Revue Thomiste,” 70 (1970), pp. 387-423 ; M. CASULA, La prova aristotelica del principio di contraddizione dal linguaggio, “Giornale di Metafisica,” 25 (1970), pp. 641-673 ; P. BEARSLEY, Another Look at the First Principles of Knowledge, “The Thomist,” 36 (1972), pp. 566-598 ; E. WINANCE, Les propositions évidentes, “Revue Thomiste,” 72 (1972), pp. 198-232 ; G. CENACCHI, Il principio di non-contraddizione fondamento del discorso filosofico, “Aquinas,” 16 (1973), pp.  255-277 ; M. C. BARTOLOMEI, Tomismo e principio di non contraddizione, CEDAM, Padua, 1973 ; L. IAMMARRONE, Tomismo e principio di non contraddizione (1), “Divus Thomas,” 79 (1976), pp. 419-433 ; G. KALINOWSKI, Le sens du discours métaphysique et les premiers principes, “Rivista di filosofia neo-scolastica,” 68 (1976), pp. 3-19 ; L. CLAVELL, Il primo principio della conoscenza intellettuale, in Atti del VIII congresso tomistico nazionale (VII), Libreria Editrice Vaticana, Vatican City, 1982, pp. 62-73 ; F. A. SEDDON, The Principle of Contradiction in “Metaphysics” Gamma, Pittsburgh, 1988 ; M. J. DEGNAN, Aristotle’s Defence of the Principle of Non-Contradiction, Minneapolis, 1990. 

[40] ARISTOTLE, Metaphysics, IV, 3, 1005b 25.

[41] ARISTOTLE, op. cit., IV, 4, 1006a 3. 

[42] ARISTOTLE, Metaphysics, IV, 4.

[43] ARISTOTLE, Metaphysics, XI, 5.

[44] R. GARRIGOU-LAGRANGE, God: His Existence and Nature,  vol. 1, B. Herder, St. Louis, 1948,  p. 168.

[45] SEXTUS EMPIRICUS, Against the Mathematicians, VII, 166.

[46] C. BITTLE, Reality and the Mind, Bruce, Milwaukee, 1959, pp. 45-47. 

[47] ST. AUGUSTINE, The City of God, II, 26.

[48] Ibid.

[49] C. BITTLE, op. cit., pp. 47-48.

[50] ST. AUGUSTINE, Contra Academicos, 3, 10, 23.

[51] ST. AUGUSTINE, De Libero Arbitrio, 2, 3, 7.

[52] ST. AUGUSTINE, De Civitate Dei, 11, 26.

[53] ST. AUGUSTINE, De Trinitate, 15, 12, 21.

[54] ST. AUGUSTINE, De Genesi ad Litteram, 12, 16, 33.

[55] Cf. De Trinitate, IX, 6, 9 (PL 42, 965-966).

[56] Cf. De Trinitate, IX, 6, 10 (PL 42, 966); De Vera Religione, 30, 54-56 (PL 34, 145-147). 

[57] Cf. De Trinitate, IX, 6, 11 (PL 42, 967).

[58] E. GILSON, The Christian Philosophy of St. Augustine, Random House, New York, 1960, pp. 87-88.

[59] “Certainly St. Augustine does not mean that illuminaton enables the human soul to see God as the direct and immediate object of vision. This opinion, which would lead to pantheism, was to be the interpretation of Malebranche and other Ontologists; but it is far from the mind of St. Augustine. Nor by illumination does St. Augustine mean that God, in the act of creating the human soul, actually infuses the ideas of the true and the good or any normative standard ready made, as Descartes affirmed later. This would make the function of divine illumination that of a kind of separate intellect, which also was far from the mind of St. Augustine. Nor did St. Augustine mean by divine illumination the ‘natural power’ of the human soul to abstract the intelligibles from the individuating determinations of the phantasm. This interpretation is not commonly accepted, because thus there would not be the distinction between the Platonic theory of knowledge followed by St. Augustine, and the Aristotelian abstraction”(C. MASCIA, A History of Philosophy, St. Anthony Guild Press, Paterson, NJ, 1957, p. 162). 

[60] C. MASCIA, op. cit., pp. 161-162.

[61] F. COPLESTON, A History of Philosophy, book 1, volume 2, Image Doubleday, New York, 1980, pp. 66-67. 

[62] In I Sent., d. 2, q. 7, G.

[63] In I Sent., d. 2, q. 4, D.

[64] Prologue, In Sent., 1, 2.

[65] J. J. SANGUINETI, op. cit., pp. 151-152.

[66] J. J. SANGUINETI, op. cit., p.152.

[67] R. DESCARTES, Principles of Philosophy, I.

[68] Ibid.

[69] R. DESCARTES, Discourse on Method, IV.

[70] Ibid.

[71] R. DESCARTES, Rules for the Direction of the Mind, Rule III, 5. 

[72] Ibid.

[73] R. DESCARTES, Meditations, I.

[74] R. DESCARTES, Meditations, II.

[75] C. BITTLE, op. cit., p. 54. 

[76] A. MILLAN PUELLES, Fundamentos de filosofía, Rialp, Madrid, 1976, p. 464. Cf. A. MILLAN PUELLES, Economía y libertad, Fondo para la Investigación Económica y Social, Madrid, 1974, pp. 162-163.  

[77] C. BITTLE, op. cit., pp. 56-58.

[78] C. BITTLE, op. cit., pp. 58-61. 

[79] J. LOCKE, An Essay Concerning Human Understanding, vol. 2, book 4, ch. 1, p. 167.

[80] J. LOCKE, An Essay Concerning Human Understanding, Introduction, Oxford, 1894, p. 32.

[81] C. BITTLE, The Whole Man, Bruce, Milwaukee, 1956, pp. 314-315.

[82] C. BITTLE, op. cit., p. 315.

[83] G. BERKELEY, Principles of Human Knowledge, I, 3.

[84] J. DE TORRE, op. cit., p. 90.

[85] C. MASCIA, op. cit., pp. 343-344. 

[86] Cf. D. HUME, A Treatise of Human Nature, Book I (Of the Understanding), Part I, Section I (Of the Origin of Our Ideas).

[87] D. HUME, op. cit., I, 2, 6.

[88] Hume repeatedly denies the objective, universal and necessary validity of the principle of causality in An Enquiry Concerning Human Understanding, which is contained in his work, Philosophical Essays Concerning Human Understanding, first published in 1748.

[89] “A prominent part of Hume’s philosophy is his theory of associationism. We speak, for example, of the principle of causality, and consider it to be a universally and necessarily valid axiom that ‘Every effect must have a cause.’ Hume claims that this axiom is derived from experience. What we perceive is an invariable sequence of events: one thing invariably follows an antecedent event, and from this sequence we conclude that the antecedent event ‘causes’ the one that follows as an ‘effect.’ We do not perceive anything like the ‘production’ of one thing by another. From his phenomenalistic, sensationalistic standpoint, Hume could not admit real ‘causation.’ Whenever we observe one event to occur, we feel the mental compulsion to assert that the other will follow. But whence the mental compulsion to conjoin just these two events as ‘cause’ and ‘effect’? Hume gives as the reason that ‘the mind is carried by habit, upon the appearance of one event, to expect its usual attendant and to believe that it will exist.’ In other words, it is the association of ideas which compels us to formulate necessary and universal judgments, axioms, and principles. Such judgements, axioms, and principles have no objective value, but are mere associations of impressions derived from the succession of phenomena”(C. BITTLE, op. cit., p. 317).

[90] “Having eliminated an objective origin for the idea of active power and the causal bond, Hume had to trace them to purely subjective conditions within the perceiver. The objects of perception are atomic, unconnected units which may, nevertheless, follow one another in a temporal sequence and pattern. Through repeated experience of such sequences, the imagination is gradually habituated to connect antecedent and consequent objects in a necessary way. The necessity does not arise from any productive force or dependence on the side of the objects so related but comes solely from the subjective laws of association operating upon the imagination to compel it to recall one member of the sequence when the other is presented. The causal bond consists entirely in our feeling of necessity in making the transition, in thought, from one object to the other. The philosophical inference from effect to cause is abstract and empty until it is strengthened by the natural relation set up by the workings of habit and association upon the imagination. Given this all-embracing psychological basis, however, causal inference can have nothing stronger than a probable import. Absolute certainty cannot be achieved, since the mind is not dealing with dependencies in being, on the side of the real things, but is confined phenomenalistically to its own perceptions and their relations. It is very likely that our habitual connection among ideas corresponds to some causal link among real things, but this can never be verified. Hence causal inference can yield only probability and belief, not certainty and strict knowledge. Hume rigidly applied this conclusion to the a posteriori argument for God’s existence, maintaining that it is, at the very most, a probable inference and nowise a demonstration”(J. COLLINS, God in Modern Philosophy, Regnery, Chicago, 1967, p. 117).   

[91] Cf. D. HUME, Dialogues Concerning Natural Religion (written before 1752 and published posthumously in 1779).

[92] Describing Hume’s nominalism, Bittle writes: “Relative to universal ideas, Hume maintains that we find a resemblance between objects and apply the same name to them; then, after a ‘custom’ of this kind has been established, the name revives the ‘idea,’ and the imagination conceives the object represented by the ‘idea’”(C. BITTLE, op. cit., p. 317). 

[93] C. BITTLE, op. cit., pp. 317-319.

[94] I. KANT, The Critique of Pure Reason, xvi, J. M. D. Meiklejohn translation.

[95] A. LLANO, op. cit., p. 97.

[96] I. KANT, op. cit., B 42 and B 49.

[97] I. KANT, Critique of Pure Reason, (trans. Max Müller), Macmillan, New York, 1927, pp. 16-17.

[98] Cf. I. KANT, op. cit., pp. 18-20, 24-28.

[99] C. BITTLE, Reality and the Mind, Bruce, Milwaukee, 1959, p. 111.

[100] A. LLANO, op. cit., pp. 94-95.

[101] I. KANT, The Critique of Pure Reason, A 19, A 109, B 34; Prolegomena to Any Future Metaphysics, Prologue 13, remark 2.

[102] I. KANT, op. cit., pp. 34, 24.

[103] C. BITTLE, op. cit., pp. 111-112.

[104] Ibid.

[105] I. KANT, Prolegomena to Any Future Metaphysics, Prologue 13, remark 2.

[106] Cf. F. COPLESTON, A History of Philosophy, Volume 6: Wolff to Kant, Image Doubleday, New York, 1985, pp. 270-271.

[107] Cf. N. ABBAGNANO, Storia della filosofia. Volume Quarto: La filosofia moderna dei secoli XVII e XVIII, TEA, Milan, 1995, pp. 346-351.

[108] I. KANT, The Critique of Pure Reason, B 311.

[109] I. KANT, op. cit., B 307.

[110] Cf. B. MONDIN, Corso di storia della filosofia, volume 2, Massimo, Milan, 1993, p. 358.

[111] C. BITTLE, op. cit, p. 312.

[112] I. KANT, The Critique of Pure Reason, 2nd ed., trans. by Max Muller, Macmillan, New York, 1900, p. 94.

[113] C. BITTLE, The Whole Man, Bruce, Milwaukee, 1956, pp. 312-313.

[114] C. BITTLE, op cit., p. 313.

[115] De Torre writes that “according to Fichte, the human spirit creates everything…. Nevertheless, as Kant noted, it is not up to me to change my observation: what is given to me in my consciousness appears to be distinct from me. But why is there a distinction between the ego and the non-ego? Why does the non-ego (external world) appear to the ego as opposed, if the ego creates the non-ego, i.e. if the principle of the non-ego is the ego? Fichte replies that if we scrutinize the human mind we will find that its most simple statement is the principle of identity: A is A. This principle is purely formal: it does not imply the existence of anything (‘A is A’ does not imply that A exists); it expresses a purely formal identity, without content. But how does the mind pass from this formal identity to an identity with existential content (in which A is a really existent A)? Here Fichte turns to Descartes: ‘I am myself’ is the most basic judgment where we find formal identity and material content together. Thus, it is by way of my own existence (I am) that I pass from purely formal identity to a formal identity with content. But I say that ‘I am myself’ when I am conscious of myself as thinking: this is the first affirmation of my existence with content. Therefore, every other affirmation of existence with real content is real to the extent that it is related to my consciousness. Fichte then declares that the ‘I’ in the ‘I am’, i.e. the transcendental Ego (not the individual and finite ego) is thus the origin of all existence. For example, when I affirm that this table is round, what I do is to affirm the existence of a round table by relating it to my consciousness of it. The empirical fact that the existence of a thing is related to my consciousness confirms that the reality of the existence of the non-ego is grounded on the reality of the existence of the ego”(J. DE TORRE, The Humanism of Modern Philosophy, Southeast Asian Science Foundation, Manila, 1989, p. 132). The primordial reality is thought: the spiritual principle of man, the pure ego, also constitutes the foundation of the non-ego. In fact, in thought functions, there is a distinction between the thinking subject and the object thought of. Therefore, to the pure ego there is added the empirical ego and the non-ego: the first is indivisible; the other two are divisible. The ultimate end of the empirical ego lies in the attainment of the pure-ego.  

[116] J. DE TORRE, op. cit., pp. 132-133.

[117] A. FAGOTHEY, Right and Reason, Tan Books, Rockford, IL, 2000, pp. 501-502.

[118] R. CHERVIN, E. KEVANE, Love of Wisdom, Ignatius Press, San Francisco, 1988, p. 280.

[119] C. BITTLE, Reality and the Mind, Bruce, Milwaukee, 1959, pp. 161-163.

[120] Quoted by William James from Leuba, in The Varieties of Religious Experience, Simon and Schuster, New York 1997, p. 392.

[121] W. JAMES, op. cit., p. 392.

[122] W. JAMES, op. cit., p. 392,  from W. BENDER, Wesen der Religion, Bonn, 1888, pp. 38, 85.

[123] C. BITTLE, op. cit., pp. 322-325.

[124] The Circle of Vienna (Wiener Kreis), initiated in 1895 as a chair of the philosophy of the inductive sciences in the University of Vienna which went to Ernst Mach, who taught a series of courses there until 1901. In 1922 the chair went to Moritz Schlick (1882-1936), who, together with a number of like-minded philosopher-physicists, published in 1929 The Scientific Vision of the World : The Circle of Vienna (Wissenschaftliche Weltauffassung: der Wiener Kries), which became the group’s manifesto. Aside from Schlick, members of the group included Rudolf Carnap (its most celebrated theorist), Kurt Gödel, Otto Neurath, Hans Reichenbach, Richard von Mises, Gustav Hempel, Karl Menger, Hans Hahn, Friedrich Herbert Waismann, and Victor Kraft.     

[125] J. J. SANGUINETI, op. cit., p. 193.

[126] J. J. SANGUINETI, op. cit., p. 194.

[127] Cf. J. MARITAIN, The Peasant of the Garonne, Macmillan, Toronto, 1969, pp. 124-132.

[128] Quoted by R. VERNEAUX, Historia de la filosofia contemporánea, Herder, Barcelona, 1971, p. 189.

[129] J. DE TORRE, op. cit., pp. 239-240.

[130] Owens gives us a scholastic epistemological explanation of the immaterial reception of the intentional species or form into the knowing subject: “Although both in perception and in material production a form is received through the activity of an efficient cause, the manner of its reception is quite different in the two cases. From what has just been seen, reception of form as studied in the philosophy of nature meant the changing of some matter from one form to another. The result was the production of a third thing. In contrast, Aristotle had described perception as meaning the reception of form ‘without the matter.’(Cf. ARISTOTLE, De Anima, 2. 12. 424a 17-b16). This did not imply that either the matter of the percipient or the matter of the thing perceived was somehow eliminated. Both percipient and thing remained corporeal beings. The Greek commentators on Aristotle gradually came to explain the phrase as referring to the manner of reception (Cf. ALEXANDER OF APHRODISIAS, De Anima, 60.3-62.4 ; THEMISTIUS, De Anima, 77.34-78.10 ; PHILOPONUS, De Anima, 437.30-438.13 ; SIMPLICIUS, De Anima, 166.3-34 ; SOPHONIAS, De Anima, 102.20-104.13). It meant that in perception the form of the thing is received ‘immaterially,’ in the sense of a reception different in kind from that which modifies or changes matter. Here the form is received in a manner that avoids alteration of anything in the natures of either the recipient or the thing perceived. It brings each into a new cognitional existence in which they are one and the same, but without change in the natures of either. It makes them exist not only together, but as one. It makes the one be the other cognitionally, with the percipient performing the act of cognition and alone have the awareness.

     “From this viewpoint, then, the reception of the form in cognition is not a material reception. Rather than being received qua cognitional into any matter, it is united with the form of the recipient in giving the one and the same cognitional existence to both percipient and thing in the actuality of the cognition. That is the way it may be regarded as a reception of form into form, in contrast to the reception of form into matter as known in the philosophy of nature. There is of course a concomitant  material reception of the modifications taking place in sense organs, nerves and brain. There is also the production of images and concepts, which are accidental entities in the category of quality (In late Scholasticism the images and concepts were known as species expressae. See John of St. Thomas, Ars Logica, 2.22.2; ed. B. Reiser, Turin, 1930, I, 702a 44-b 18. In contrast, the term species impressa was used for the form received through the action of the sensible thing or of the agent intellect). These all are means by which or in which the cognition takes place. They are produced through an internal activity with its form given by the distant cause that is acting efficiently upon the percipient... the percipient, besides having the physical potentiality to receive the images in material fashion on the retina of his eyes, has also the cognitional potentiality to receive their forms immaterially and thereby to become what the retinal images represent.

     “…the notion of immateriality in cognition arises from the way the form of a thing is received in perception. No change or alteration is caused in the thing by the cognitional reception. Both percipient and thing perceived remain material beings. They do not become immaterial themselves through the act of perceiving. The cow you see in the field remains a material object when it comes to exist immaterially in your cognition. There is no such thing as an immaterial cow, either outside or inside the mind. Its nature requires it to be material, and the perception of it does not change its nature. Nor do you yourself become an immaterial agent when you are reflexively aware of your own self in the act of perceiving the cow. The designation ‘immaterial’ in regard to cognition arises from the way the form is received in perception. It does not require that either agent or object be without matter.

     “Nevertheless it is correct to say in Scholastic terminology that immateriality is the root of cognition, that the grades of cognition vary according to the degrees of immateriality, and that in this way the nature of cognition lies in immateriality (See AQUINAS, De Veritate, q. 2, a. 2, c. ‘Immateriality,’ in this meaning, is not restricted to purely spiritual things, since it applies to the cognition of the senses. The application of it to cognition is based upon the way form is received in cognition, a way different from the physical modification of matter, and meaning reception of form into form.)”(J. OWENS, Cognition: An Epistemological Inquiry, Center for Thomistic Studies, Houston, 1992, pp. 43-45).    

[131] P. GLENN, Cosmology, B. Herder, St. Louis, 1941, p. 148.

[132] P. GLENN, op. cit., p. 152.

[133] T. ALVIRA, T. MELENDO, L. CLAVELL, op. cit., p. 196.

[134] J. J. SANGUINETI, op. cit., p. 203.

[135] “Exceptions to this distinction are noted in the case of pure spirits (angels) and more so in the case of God, regarding the knowledge of their own essence. The object here is intelligible in itself, immediately present to the subject, and proportioned to its mode of knowledge. At this peak of reality, the order of nature is identical with the order of intention, and, therefore, no representative species is required. If, however, it were objected that the soul of man, which is an immaterial form and therefore intelligible in itself and immediately present to the knower, is not known except by means of a very imperfect representative species, the answer, as we shall explain later, is that this object is not proportioned to the human intellect, which has for its proper object material essences.”

[136] “The subject must somehow be immaterial in order to know. The species, being received in the knower, must also be free from matter according to the degree of immateriality of the subject, since whatever is received must be received according to the nature of the receiver: ‘…the sensible form is in one way in the thing which is external to the soul, and in another way in the senses, which receive the forms of sensible things without receiving matter, such as the color of gold without receiving gold. So, too, the intellect, according to its own mode, receives under conditions of immateriality and immobility the species of material and movable bodies; for the received is in the receiver according to the mode of the receiver’(Summa Theologiae, I, q. 84, a. 1, c.)”

[137] “‘…the known material things must exist in the knower not materially, but rather immaterially. The reason for this is that the act of knowledge extends to things outside the knower’(Summa Theologiae, I, q. 84, a. 2, c.). When a material object is known, it is ‘received’ in the knower. This reception is not a material reception. Rather, this ‘reception’ of the object means that a representative species is educed from the operative potency (in the case of human knowledge) by the action of the object. Now, to exercise this action, the object must somehow be in act. This, however, would not be possible if the corporeal object did not possess a faint vestige of the immaterial, of actuality.

     “All limited beings, even those that are lowermost in the scale of reality, participate in immateriality. The reason is that all limited beings, precisely because they are beings, must participate in the Being that is the pure act of being and which therefore is pure Immateriality. Consequently, no matter how weak this participation is, no matter how deeply immersed in matter the form may be, there remains a trace of that which it shares, of that which makes it real, which makes it be. It is by reason of this actual element that a material object is able to actuate, to move the human cognitive potency.”  

[138] H. RENARD, op. cit., pp. 99-102.

[139] E. GILSON, El realismo metódico, Rialp, Madrid, 1952, p. 78.

[140] E. GILSON, op. cit., p. 104.

[141] A. LLANO, op. cit., pp. 117-118.

[142] H. RENARD, op. cit., p. 108.

[143] T. J. SEJNOWSKI & P. S. CHURCHLAND, Brain and Cognition, in M. I. POSNER (Ed.), Foundations of Cognitive Sciences, MIT Press, Cambridge, MA, 1989, pp. 301-356. 

[144] Cf. A. M. TURNER & W. T. GREENOUGH, Differential Rearing Effects on Rats’ Visual Cortex Synapses, “Brain Research,” 329 (1985), pp. 195-203.  

[145] Cf. P. J. SELKOE, Amyloid Protein and Alzheimer’s Disease, “Scientific American,” 265 (1991), pp. 68-78.

[146] Cf. J. R. COOPER, F. E. BLOOM & R. H. ROTH, The Biochemical Basis of Neuropharmacology, Oxford University Press, New York, 1986.

[147] There are four major nuclei of the thalamus which relay visual, auditory, somatosensory, and equilibrium-related information: 1. the Lateral geniculate nucleus, which permits us to see, receives information from the visual receptors via optic nerves and transmits information primarily to the visual cortex; 2. the Medial geniculate nucleus, which permits us to hear, receives information from the auditory receptors via the auditory nerves and transmits information primarily to the auditory cortex ; 3. the Ventroposterior nucleus, which permits us to sense pressure and pain, receives information from the somatic nervous system and transmits information primarily to the primary somatosensory cortex; and 4. the Ventrolateral nucleus, which permits us to sense physical balance and equilibrium, receives information from the cerebellum in the hindbrain and transmits information primarily to the primary motor cortex.

[148] J. OWENS, op. cit., p. 105.

[149] J. E. ROYCE, Man and His Nature: A Philosophical Psychology, McGraw-Hill, New York, 1961, pp. 59-60.

[150] C. BITTLE, The Whole Man, Bruce, Milwaukee, 1956, pp. 92-93.

[151] J. E. ROYCE, op. cit., p. 62.

[152] In IV Metaphysicorum, lect. 13, no. 668.

[153] Cf. J. GREDT, Unsere Aussenwelt. Eine Untersuchung über den gegenständliche Wert der Sinneserkenntnis, Tyrolia, Innsbruck, 1921, pp. 165-184.

[154] A. LLANO, op. cit., p. 76-77. 

[155] J. J. SANGUINETI, op. cit., pp. 216-217.

[156] Summa Theologiae, I, q. 78, a. 3, ad 2. 

[157] R. E. BRENNAN, op. cit., pp. 122-123.

[158] J. J. SANGUINETI, op. cit., pp. 214-215.

[159] E. GILSON, El realismo metódico, Rialp, Madrid, 1952, p. 159.

[160] A. LLANO, op. cit., p. 78.

[161] De Veritate, q. 1, a. 11.

[162] C. BITTLE, op. cit., pp. 150-151.

[163] Studies on the sensus communis: B. MULLER-THYM, The Common Sense, “Thomist,” 1940, pp. 315-343 ; E. J. RYAN, The Role of the Sensus Communis in the Philosophy of St. Thomas Aquinas, Messenger Press, Carthagena, OH, 1951.  

[164] G. P. KLUBERTANZ, op. cit., p. 124.

[165] G. P. KLUBERTANZ, op. cit., p. 128. 

[166] H. REITH, op. cit., p. 100.

[167] H. D. GARDEIL, op. cit., p. 70.

[168] Ibid.

[169] H. REITH, op. cit., p. 101.

[170] Cf. Summa Theologiae, I-II, q. 50, a. 16, c.

[171] H. REITH, op. cit., pp. 85-89.

[172] C. BITTLE, op. cit., p. 171.

[173] M. MAHER, Psychology, Longmans, Green, and Co., London, 1930, p. 165.

[174]Recognition or Remembrance. By this is meant the apprehension of the sameness of two representations or perceptions, one present and one past. I am aware that my present representation or perception is identical with a representation or perception which I have had on a former occasion.

     “It may be a question of two perceptions, as when I see a traffic policeman on a corner and remember that I had seen him there yesterday. Or, of two representations (phantasms), as when I imagine Times Square in New York and then remember that I also imagined it last week. Or of a perception and a representation, as when I see a friend and then remember that I had thought of him (imagined him) only an hour ago. Or, of a representation and a perception, as when I imagine the Old Faithful geyser and remember that I had seen it a number of years ago. These are instances of recognition or remembrance, and the past and present are always linked together.

     “Mere knowledge of the sameness between one thing and its representation is not sufficient to classify this knowledge as ‘remembrance.’ For example, I visit a man in his home and I see, let us say, his photograph on the mantlepiece while he is conversing with me. Although I perceive the sameness between this man and the man on the photograph, this is an instance of mere knowledge without memory, because both perceptions occur simultaneously. On the other hand, if I see the man now and recall that I have seen him formerly, it is a case of memory and not of mere knowledge.

     “The objects of memory are always accompanied by a feeling of familiarity, of acquaintanceship. Oftentimes we see an object or person, or we hear a melody, or we feel a pain; almost immediately the object, person, melody, pain, etc., seems familiar to us, as if we had had the experience before. A little effort may recall the exact occasion of the former experience, and then the act of memory is complete. It may happen, though, that no amount of effort enables us to recall the occasion; while it is possible that we may be mistaken concerning the fact of a former experience, this ‘familiarity’ probably indicates a confused and vague remembrance.

     Estimation and Measurement of the Past. It is a fact of everyday occurrence that we date and localize our experiences in memory by placing them at a definite point in the chain of events reaching into the past; and it is a further fact that we concretely measure the time when the past experience took place. How is this estimation and measurement accomplished?

     “The psychological process is as follows. The stimulations of the external senses and the perceptions of the central sense occur successively, so that we have a series of internal conscious states following one after the other. We can gauge the slowness or rapidity of the flow of our internal acts by the rhythmic movements of the breathing of the lungs or of the beating of the heart. We thereby possess a means of estimating and measuring subjective time in a concrete manner. By using this standard of subjective time we can now estimate and measure the objective time involved in the sensations and perceptions of objects. The succession of events as we perceived them is fixed according to a ‘before’ and ‘after’ in the very series itself. If we now represent to ourselves this internal series of perceptual events, from the present backwards, we not only apprehend ‘time’ and the ‘duration’ of time concretely, but we are able to ‘date’ and ‘localize’ a particular event by placing it at a definite point in the series of past events. Certain external events in this series, such as night and day and the annual seasons, stand out in stong relief and become fixed points for dating other events. In this manner we become accustomed to using subjective and objective time for dating and localizing events in memory.

     Brutes, too, possess memory. A dog remembers the location of his kennel, recognizes his master, and knows what to do or not to do at a certain command. A delivery-wagon horse remembers all the stops on his regular route. Pigeons remember the cote to which they belong. Bees roam far afield, but they return unerringly to their own hive. Robins discover a cherry tree or a strawberry patch and always find their way back. The training of animals is based on the fact of their being able to remember a certain sequence of actions. Many of the conditioned reflexes induced in the animal experiments of Pavlov and others would be impossible, if the animals had no memory.

     “Animals have also a concrete estimation of time. The cattle on the farm wend their way to the barn when milking time arrives. Some dogs will stand at the gate every evening at the same time, awaiting the master’s return from work. Pigeons remember their regular feeding time and congregate accordingly. In the salivary conditioned-reflex experiments, if the routine calls for food to be given one minute after the signal, the animal remembers the time interval, and salivation does not start until toward the end of the interval. Such instances and experiments prove that animals have memory and estimation of time.

     “In all that has been said here about time and its estimation, it should be noted that it is the sensory memory that is involved. The abstract concept of time is an object of intellectual insight and is treated in cosmology”(C. BITTLE, op. cit., pp. 192-194).

[175] Studies on the estimative/cogitative sense: L. L. BERNARD, Instinct, Holt, New York, 1924; E. C. WILM, Theories of Instinct, Yale University Press, New Haven, CT, 1925 ; R. ALLERS, The Vis Cogitativa and Evaluation, “New Scholasticism,” 15 (1941), pp. 195-221 ; J. PEGHAIRE, A Forgotten Sense, the Cogitative, According to St. Thomas Aquinas, “Modern Schoolman,” 20 (1943), pp. 123-140 ; T. V. MOORE, The Driving Forces of Human Nature and Their Adjustment, Grune & Stratton, New York, 1948 ; T. V. FLYNN, The Cogitative Power, “Thomist,” 16 (1953), pp. 542-563 ; R. FLETCHER, Instinct in Man: In Light of Recent Work in Comparative Psychology, International Universities Press, New York, 1957.  

[176] H. REITH, op. cit., pp. 106-107.