Epistemology, Great Books, Metaphysics, Ontology, Philosophy

On the Intellect, Induction, and Abstraction

by Dave Seng

It was a good idea to call the soul ‘the place of forms’, though (1) this description holds only of the intellective soul, and (2) even this is the forms only potentially, not actually. – Aristotle

[Note: In my previous posts, I spoke about Aristotelians and Thomists as being innatist in their epistemology. I should have been more clear about this terminology because realists are not innatists in the Platonic sense. Human beings are not cognitively pre-loaded with the Platonic forms. Aristotelians are innatist in a very strict sense. What is innate, according to classical realists, is the capacity or potential to receive the form, universal, or essence of the sense object as it is in act. (See, for example, the last chapter of Aristotle’s Posterior Analytics for further explication.) I will try to develop this theme as we move along.]

In our most recent posts on Berkeleyan idealism, we learned that the mind is structured to receive and apprehend reality as it is. In other words, being is the touchstone of all reality. Being is, and can not be denied (it can not be otherwise because it would be non-being or nothing). We also learned that the intellectual faculty of judgment has both metaphysical (ontological) and epistemic or psychological aspects. When the mind is working correctly, one knows reality. Concrete reality is the proper starting point for metaphysics, not one’s theory about it (one’s theory of reality could be wrong, which is why, again, being is the touchstone of reality). In this post, I will try to explicate the basics of how the intellect works at the foundational level—at the reception of being—what Aristotelian philosophers call the intellect. This will lay the groundwork for why metaphysical realists claim that one can know reality as it is and provides further insight into the distinction between apprehension and concept—the central confusion and philosophical error among idealists, although I will develop that in upcoming posts. For now, it is important to understand how the intellect itself works.

First, what is the intellect? The word comes from the Latin terms, intus, and legere—to read within. The intellect is the cognitive capacity that humans have to think rationally, carefully, and logically about the perennial questions of existence as they find it. It is the intellect and the ability to reason which separates humans from animals. Although humans are animals, they are not simply or just animals. It should be obvious that humans have different cognitive abilities than that of animals. In addition to sense knowing, which all animals have, humans have the ability to reflect on and arrive at deeper understandings of their sense knowledge. As noted in previous posts, to sense something and to understand something is not the same thing. I can hear a foreign language but not understand it. My cat can see the same image of a sign on its retina as I do, but have no understanding of what it means, while I can easily grasp its message. Just as humans are different in kind from animals, there must be some faculty in the human mind that is different in kind from simple sense perception. This faculty is called the intellect or what philosophers in the Aristotelian and Thomist traditions call the agent intellect.

The agent intellect is a special faculty of the mind and has two important functions. First, the intellect is in potency to knowledge—it does not know to start with (it requires the act of existence to motivate it because it depends on being, as act is prior to potency). Second, as immaterial, the intellect receives the essence, universal, or form of the external object through sense perception. Aquinas reminds us, “Now it is natural to man to attain to intellectual truths through sensible things, because all our knowledge originates from sense.”1 The senses are the only connection one has to reality. Even so, what comes into the intellect has an immaterial rather than material mode of existence. The tree I am looking at through the window does not exist as a physical tree in my mind. The intellect grasps the form or essence of the sense object. This is because there is an immaterial aspect to all reality. To account for this essential reception, however, there must be a prior ability, capacity, or function in the intellect which apprehends the form of the material object. The same form of the material object exists in the intellect that exists in reality, only the mode of existence is different. This second function of the intellect is an immaterial apprehension of the material form or essence. This is what Aristotle calls the agent intellect and the reason why he calls the intellect, or soul, “the place of the forms.”2 The agent intellect apprehends the essence of the thing perceived. The nature of the agent intellect is to receive the object of sense perception3.

A question remains, however. How do the forms or universals get into the intellect?

The intellect is in potency to knowledge and has a capacity to receive the essence of an external object. Now, it is important to understand how the form or essence of a thing is delivered to the intellect. Briefly, this is accomplished by induction and abstraction. Induction, or inductive reasoning, is the logical process of thinking in which the conclusion follows from experience, examination of particulars, and arriving at generalized or universal principles—for Aristotelians, the foundation of all subsequent reasoning. Aristotle held that wider and wider generalization is derived from repeated empirical experiences of particular things until the essence or universal concept is established in the intellect. Philosopher Ed Miller puts Aristotelian inductive reasoning it this way:

From the experience of the particular man Callias, the man Socrates, the man James, the man Tad, the man Bill … the intellect derives the general or universal idea of man, that is man as such. From the experience of the particular dog Fido, the dog Lassie, the dog Rover, the dog Flip … the intellect derives the universal idea dog. And the universal ideas—man, dog, and innumerable other concepts derived from experience in the same manner—become the tools and building blocks of all reasoning. They then make it possible to say and know, “Socrates is a man,” “In fourteen hundred and ninety-two Columbus sailed the ocean blue,” etc.4

Aristotle compares the formation of the universal in the intellect to the formation of soldiers making a stand against a wartime enemy:

We conclude that these states of knowledge are neither innate in a determinate form, nor developed from other higher states of knowledge, but from sense-perception. It is like a rout in battle stopped by first one man making a stand and then another, until the original formation has been restored. The soul is so constituted as to be capable of this process. . . . When one of a number of logically indiscriminable particulars has made a stand, the earliest universal is present in the soul: for though the act of sense-perception is of the particular, its content is universal—is man, for example, not the man Callias. A fresh stand is made among these rudimentary universals, and the process does not cease until the indivisible concepts, the true universals, are established: e.g. such and such a species of animals is a step towards the genus animal, which by the process is a step towards a further generalization. Thus it is clear that we must get to know the primary premisses by induction; for the method by which even sense-perception implants the universal is inductive.5

In fact, Aristotle believes induction to be the basis of all other knowledge:

From experience again—i.e. from the universal now stabilized in the soul, the one beside the many which is a single identity within them all—originate the skill of the craftsman and the knowledge of the man of science, skill in the sphere of coming to be and science in sphere of being.6

Metaphysics, the study of being as being, is the science in the sphere of being. In other words, metaphysics is a kind of science in the Aristotelian and Thomist tradition. Being is at the center of whatever is thought or done. One can not change the oil in his truck or complete a math equation without referencing being. Being, however, is the first act of knowing. The intellect can only understand the universal or essence of any external object through induction.

Aristotle’s notion of induction is very similar to the concept of abstraction put forward by St. Thomas. Aquinas focuses on the idea that the mind can remove, withdraw, or pull out the concept of redness from viewing various red objects. One understands the concept of justice by examining just actions. Abstraction is a general idea, universal, or essence that the intellect removes from the multiple expressions of the same form found in the particular instances of it (the essential nature of the particular whether it be dog, cat, chair, human, or concepts such as the good, true, beautiful etc.).

St. Thomas helps us understand how the intellect moves from the particular to the universal (here “intelligible species” means essence. “Phantasms” are the mental images of things):

Our intellect cannot know the singular in material things directly and primarily. The reason of this is that the principle of singularity in material things is individual matter, while our intellect … understands by abstracting the intelligible species from such matter. Now what is abstracted from individual matter is the universal. Hence our intellect knows directly the universal only. But indirectly and as it were by a kind of turning back (reflectio), it can know the singular, because … even after abstracting the intelligible species, the intellect, in order to understand actually, needs to turn to the phantasms in which it understands the species. … Therefore it understands the universal directly through the intelligible species, and indirectly the singulars represented by the phantasms. And thus it forms the proposition, “Socrates is a man.”

Classical realists, then, begin with being—the concrete particular things encountered in the sensible external world. Being is more than physical reality but never less than it. With the universal firmly in place in the intellect one is enabled to return and know reality through reflection and judgment. One can genuinely think about reality, know it, and express it, “Socrates is a human being.”

For Further Reading:

Holloway, M., “Abstraction from Matter in Human Cognition”, The Modern Schoolman, Vol. XXIII (1946), pp. 120 – 130.

For a more general introduction to Thomist epistemology see:

Wilhelmsen, Fredrick. Man’s Knowledge of Reality: An Introduction to Thomistic Epistemology. Englewood Cliffs, N.J.: Prentice-Hall, Inc., 1956.

I wrote about the Aristotelian distinctions of act and potency here.

Works Cited

Aquinas, Thomas. The Summa Theologica Volume 1. The Great Books of the Western World, edited by Mortimer J. Adler et al., Vol. 17, Encyclopedia Britannica, 1996.

Aristotle. The Works of Aristotle Volume 1. The Great Books of the Western World, edited by Mortimer J. Adler et al., Vol. 7, Encyclopedia Britannica, 1996.

Miller, Ed. Questions that Matter: An Invitation to Philosophy. New York: McGraw-Hill, 1996.

Footnotes

1Thomas Aquinas, Summa Theologica, Trans. by Father Laurence Shapcote of the Fathers of the English Dominican Province (Chicago: Encyclopedia Britannica, 1996) 1a, q.1, art. 9.

2Aristotle, On the Soul (De Anima), Trans. by J. A. Smith (Chicago: Encyclopedia Britannica, 1996) 661.

3 While we are distinguishing the important faculties of the intellect, it is also very important to be aware that the whole person is involved in knowing. This requires a bit of development and goes beyond the scope of this post but I plan on explicating this notion in time. For now, it is important to understand that for those in the Aristotelian and Thomist tradition, the entire person is involved in apprehending reality. This is because form and body (matter and form) are united and should never be separated. Not only does the individual know and understand things through deduction and induction, humans also know through connatural knowledge—the lived and embodied contact one has with others and reality itself. This involves knowing through empathy, lived human experience, intuition, and the contact of the intellect with the truth of reality itself by other holistic ways of knowing such as imaginative literature, the arts, and history. Embodied knowledge means knowledge through the whole person and by way of all the arts and sciences. The Platonic tradition sees form and matter as separate which, if unchecked, leads to idealism. Idealism is the result of disembodied knowledge, a disembodied epistemology. Platonist metaphysics rests on the separation of form from matter and provides the foundation for the error of idealism.

4Ed Miller, Questions That Matter: An Invitation to Philosophy (New York: McGraw-Hill, 1996) 235.

5Aristotle, Posterior Analytics (Analytica posteriora), Trans. by G.R.G Mure (Chicago: Encyclopedia Britannica, 1996) 136.

6Aristotle, Posterior Analytics, 136.

Intellectual History, Liberal Arts, Metaphysics

Berkeley, Classical Realism, and the Metaphysical First Principles of Being, Part Three

by Dave Seng
Alfred North Whitehead (1861 – 1947), Metaphysical Realist

This is part three of a three part examination of Berkeleyan subjective idealism. Part two can be found here. Part one can be found here.

When it comes to epistemology, the mind through its innate intellectual capacity to make judgments, utilizes the laws of logic as the starting points of understanding reality. The first principles of knowledge are innate intellectual capacities or functions of the mind by virtue of the mind’s ability to know reality and make judgments about it. Realists, therefore, are innatists, meaning that certain functions of the mind are innate, simply because the mind is an essential feature of being human. Judgment is a natural part of the human intellect. One may not immediately understand the first principles they are using, but they may be easily affirmed and recognized through education and reflective questioning just as Plato demonstrated with the slave-boy in the Meno dialogue, and as Aristotle affirms as intuitively correct in his Posterior Analytics1. Therefore, the human mind has an innate, or natural capacity to understand reality through judgment but knowledge is developed explicitly through discussion, questioning, examination, and education. Even the empirically-minded Aquinas believes that the mind has a natural tendency for understanding first principles. Aquinas explains, “Each power of the soul is a form or nature, and has a natural inclination to something. Therefore each power desires by the natural appetite that object which is suitable to itself” (Ia q. 80, a. 1, ad. 3). And, “The natural appetite is that inclination which each thing has, of its own nature, for something” (Ia, q. 78, a. 1, ad 3). For Aquinas, and most forms of realism, human beings have innate first principles or cognitive functions of the intellect. When these mental capacities are given the content of sense experience, human beings are able to come to a correct knowledge of reality. This also means that deductive rational reasoning and empirical experience work together symbiotically.

Of course, one could examine many other first principles of reality such as the law of universality, the principle of causality, the principle of finality, or the more narrow principles of induction or empiricism, but the most important are the laws of logic because they apply equally to metaphysics and epistemology. Just as there are different faculties of the mind, there are logical first principles which are related ontologically and epistemically. These first principles come from the innate cognitive faculty of judgment and are derived from reality itself because one cannot deny what is. In fact, the foundational principles of knowing and logic are properties of being itself. Aquinas thinks that understanding the basic first principles of being is an act of wisdom,

“Now to know the meaning of being and non-being, of whole and part, and of other things which follow on being, which are the terms of which indemonstrable principles are constituted, is the function of wisdom … And so wisdom makes use of indemonstrable principles which are the object of understanding not only by drawing conclusions from them, as other sciences do, but also by passing its judgment on them, and by vindicating them against those who deny them.” (I-II, q. 66, a. 5, ad. 4)

Here, it becomes important to review the first (or primary) laws of logic, because they relate to both existence (what can or cannot be), and how one knows it (what can or cannot be known). The laws of logic have both metaphysical and epistemic implications. As such, they set forth the first principles of reality and knowledge. The first principle of knowledge is the law of noncontradiction. The law of noncontradiction states that nothing can both be, and not be at the same time and same respect. This is a metaphysical and ontological claim because being cannot both exist, and not exist in the same manner (no object has that property including being itself). This principle is simply expressing the notion that being and nonbeing are ontologically different things and is why the law of noncontradiction is a property reality itself. The first judgment the mind makes when it experiences anything is that something is rather than is not, which makes it also an epistemic principle of reality. The law of excluded middle is equally important. The law of excluded middle is the principle that something either is, or it is something else, but cannot be both at the same time.2 Something must either be, or not be. A sea creature is either a fish, or a cephalopod, but not both at the same time or something in-between. Metaphysically, something cannot both be and not be in the same manner. Language depends on this principle as well—a statement is either true or false, but not both at the same time. If that were not the case, all meaningful communication would collapse into incoherence. Finally, the law of identity indicates the unity of things and being itself. Metaphysically, the law of identity draws one’s attention to the fact that a thing is what it is. The unity of being speaks to the fact that being is, and is intelligible. There are fundamental universal consistencies of being which make something what it is and intelligible to the mind. Epistemologically, a true statement must be true, a false statement must be false. These are the first principles of reality and all human knowledge. These principles are not mind dependent, they are properties of objective being and reality.

The innate ability of the mind to make determinations and judgments about reality does not mean that the mind is ultimate in determining reality. Contrary to Berkeley, being is not a construct of the mind. The mind apprehends being, but does not create it. Rather, the first principles of knowledge point to the fact that the mind is subservient to being. It first receives being, then makes a judgment according to what is or is not (the law of noncontradiction). But “what is” is unaffected, unchanged, and essentially untouched whether or not it is perceived. The only reason I can say that Los Angeles is in California and that I exist is because reality is that way. Berkeleyan idealism holds that all reality is mind-dependent and a construct of mental perception (whether one’s own or an eternal spirit’s). Realists maintain that the mind does not construct reality, it conforms to it. When I fly on an airplane to Los Angeles, I must adjust to this objective reality—including the ultimate principles that will get me there—the principle of causation, the principle of predictive uniformity, and various other laws of physics which are properties of being, and exist completely independently of what I think about them, or whether or not I perceive them. Berkeley’s subjective idealism reduces being to mind alone, and fails to account for the ontological first principles of objective external reality.

Works Cited

Aquinas, Thomas. The Summa Theologica: 1. Great Books of the Western World. Vol. 17. Encyclopedia Britannica, Inc., 1999.

Aristotle. The Works of Aristotle: 1. Great Books of the Western World. Vol. 7. Encyclopedia Britannica, Inc., 1999.

Berkeley, George. The Principles of Human Knowledge. Great Books of the Western World. Vol. 55. Encyclopedia Britannica, Inc., 1999.

Whitehead, Alfred North. Science and the Modern World. Great Books of the Western World. Vol. 55. Encyclopedia Britannica, Inc., 1999.

1For Plato’s account of the slave-boy see Plato, Vol. 6, 180 – 184. Aristotle acknowledges that rational deduction is one part of knowing reality and affirms Plato’s account in his Posterior Analytics, Vol. 7, 97. Aristotle, however, fine tunes Plato’s argument and suggests that both rational deduction and inductive empirical observation are needed to come to a true and full understanding of reality.

2The principle of either/or is what makes logic gates and modern digital computing possible.

Intellectual History, Metaphysics, Philosophy

Berkeley, Classical Realism, and the Metaphysical First Principles of Being, Part Two

by Dave Seng
St. Thomas Aquinas, also called Doctor Angelicus (Latin: “Angelic Doctor”),  born 1224/25,—died March 7, 1274.

Part one can be found here. This is part two of a three part series which reflects on Berkeleyan idealism in light of classical realism.

A foundational concept in Berkeley’s philosophy is that reality depends on a perceiver in order for it to be (the esse in his famous dictum). And this is the point of contention for classical realists. Is it correct to say that reality is structured in such a way that it must be perceived to exist? (Additionally, an outright denial of the existence of matter seems problematic and is, in fact, Gnostic.) Classical realism takes both perception and objective reality seriously because sense experience is the only connection one has to the world. The realist finds the entire project of proving an external world to be supremely uninteresting and quite unnecessary. Regarding the faculties of the mind, the act of perception is different from other cognitive abilities like thought, memory, or imagination. Thinking is not the same as having a sense perception. One can think through an issue or problem, recall a memory, or use one’s imagination (such as reading a work of fiction or pondering the existence of centaurs). When these faculties, or acts of the mind, are engaged one can always ask the additional reflective question of whether or not they exist in external reality. When it comes to the faculty of perception, however, one cannot separate one’s perception of an object from its actual existence in reality. Normal perception is always the perception of an external object. If that were not the case, there would be no difference between reality and hallucination. When one asks about hallucinations, external objective reality is assumed in the question, or it would not be a question.1 Perception is what gives human beings the ability to distinguish between appearance and reality (in order to correct a faulty sense appearance, one simply has another sense experience). The faculty of imagination, however, consists of the ability to think of objects that do not exist in reality. In contrast, the faculty of perception is always of something, an external object. Classical realists hold that humans are cognitively structured to be of, about, and oriented towards reality. It makes little sense to say one has a physical perception of a tree and, at the same time, that the tree does not exist. The logical laws of non-contradiction, identity, and excluded middle still hold with sense perception. It does no good to deny external reality. When the mind works correctly, there is no need to prove an external world. Human perception is always of something. In metaphysical terms, that which is cannot be denied.

Berkeley’s conflation of thinking with perception utterly confuses the most important aspects of reality itself—the subjective and objective, appearance and reality, being and becoming, the one with the many, and ultimately equates thought, or mind, with Being. Instead of clarifying reality or explicating the nature of reality, Berkeley only adds more confusion to these ultimate questions. If Berkeley’s interpretive scheme of reality is correct, there is no way to explore the metaphysical nature of reality. The field of metaphysics, itself, would be impossible. The rejection of any reality external to one’s mind undermines the task of metaphysics which is to discover the objective first principles of being as being, at least according to the Aristotelian definition of metaphysics.

Further, classical realists hold to compresence—the idea that minds and objects are both part of reality and co-related. Because human beings live in a common world of sense, they can also share a common world of thought and intellectual engagement. As Alfred North Whitehead explains, “I do not understand how a common world of thought can be established in the absence of a common world of sense” (178). Human beings share the same basic reality and the mind is tuned to the concrete requirements of objective existence. Reality has its own intractable way of being and it is objectively intelligible, discoverable, and shareable with others through the tools of reason—sometimes by way of induction, other times by deduction, and sometimes both working together. Being itself is the unifying standard of all thought and physical activity. The realist, therefore, maintains that all thought and human action takes place in objective time and space.

As extreme as Berkeley appears to be, it is important to take a closer examination of his perspective, and we will explore this further in upcoming posts. For now, keep in mind that no great philosopher or author is completely wrong. Berkeley’s idealism forces one to think about the nature of reality at a deeper level. Perhaps one reason for including Berkeley as one of the great Western philosophers that (although epistemically wrong), he forces one to think more carefully, rationally, and critically about the most fundamental questions of reality. Even when a thinker is wrong, an examination of the position is still instructive. Berkeley raises several questions that the realist wisely takes seriously. How should one think about reality or being? What role does the mind have in knowing reality? And what are the ultimate principles of reality, if any?

While idealists such as Berkeley insist that reality is determined by the mind, or immaterial spirit, realists like Aristotle and Aquinas pose a different strategy for understanding reality and offer a way to think about being that neither denies the role of the mind, nor rejects external reality. When it comes to epistemology, realists believe that there must be first principles of knowledge. An examination of these first principles will demonstrate the role that the intellect plays in knowing reality. The first principles of knowledge are self-evident and foundational to all other knowledge.

All the sciences are derived from basic self-evident first principles. Aquinas puts it this way, “The principles of any science are either in themselves self-evident, or reducible to the knowledge of a higher science” (Ia, q. 1, a. 2 ). And, “The word ‘principle’ signifies only that from which another proceeds: For anything from which something proceeds in any way we call a principle” (Ia, q. 33, a. 1). Self-evident truths are principles that are foundational to all knowledge, and are impossible to deny (such as logical truth, the law of noncontradiction, mathematical truth such as the axioms of geometry, and moral truths such as the proposition that it is always wrong to rape women)2. Self-evident truths are the starting points for any scientific or philosophical inquiry. First principles do not provide the content of reality, rather, they are what make knowledge of reality possible. Classical realists do not deny that the mind has a role when it comes to understanding reality.

Aquinas also refers to first principles that are reducible to the knowledge of a higher science. This occurs when, for example, one understands that music relies on mathematical formulas, or the scientific method rests on the ultimate metaphysical principles of the law of causality, law of predictive uniformity, law of noncontradiction, and others. In fact, it was Aristotle who claimed that it was the mark of an uneducated person not to realize that there must be certain first principles of reality such as the foundational law of noncontradiction (Aristotle, Vol. 7, 525).

In our next post, we will discuss the first principles of being, which are properties of reality and through which we come to understand what is. The first principles of reality are both ontological and epistemic in nature.

1Hallucination is pathological. When the mind is functioning correctly, perception is not pathological, it is normative. When determining between reality and hallucination, external objective existence is assumed.

2Self-evident truths, or first principles, are often intuitive but they can become explicit, usually through education. They are impossible to deny because they must be assumed in any attempt to deny them.

Works Cited

Aquinas, Thomas. The Summa Theologica: 1. Great Books of the Western World. Vol. 17. Encyclopedia Britannica, Inc., 1999.

Aristotle. The Works of Aristotle: 1. Great Books of the Western World. Vol. 7. Encyclopedia Britannica, Inc., 1999.

Berkeley, George. The Principles of Human Knowledge. Great Books of the Western World. Vol. 55. Encyclopedia Britannica, Inc., 1999.

Whitehead, Alfred North. Science and the Modern World. Great Books of the Western World. Vol. 55. Encyclopedia Britannica, Inc., 1999.

Intellectual History, Metaphysics, Philosophy

Berkeley, Classical Realism, and the Metaphysical First Principles of Being, Part One

by Dave Seng
George Berkeley

Introductory Note: In 1995 Dr. Mortimer Adler wrote that idealism is “the greatest of all modern philosophical mistakes” (Adler 118). I believe that Dr. Adler is correct. Today, much of postmodernism, post-structuralism, and critical theory in all its forms is the result of idealism. To echo Richard Weaver, ideas have consequences. The next few posts will examine a particular form of idealism as represented by the Anglican bishop George Berkeley (1685 – 1753). The following posts will only look at Berkeley’s subjective idealism in general terms and then follow with the classical realist response. Berkeley’s most important and specific errors will be addressed later (such as his implicit Gnosticism). For now, just keep St. Athanasius in mind — That which is not assumed is not redeemed.

When it comes to understanding what is ultimately real (metaphysics), many of the truly great authors in the Western intellectual tradition can be divided between those who hold to idealism (that reality consists of mind and its ideas), and realism (that objects of sense perception exist independently of their being known). For the idealist, the mind is ultimate in determining reality, while the realist holds that being, or reality itself, is the proper starting point for philosophical reflection. The realist asserts that the realms of both consciousness (mind) and external objects exist and belong to the overall structure of Being. In one form or another, idealists believe that the contents of the mind are all that can be really known and the mind is the arbiter and, in some ways, creator of reality. In the history of Western thought, Berkeley, Kant, and Hegel hold to forms of idealism, and Aristotle, Aquinas, and Whitehead represent realism.1 The next few posts will explore George Berkeley’s subjective idealism in light of classical realism (understood from the perspective of Aristotle and Aquinas), and assess the merits of holding to both mind and matter as the essential structure of reality, and explores whether or not Berkeley’s metaphysical position takes into account the first principles of being.

It is helpful to understand Berkeley’s version of subjective idealism before presenting and explicating classical realism. For Berkeley, perception is not simply direct sensation, it includes all the physical senses and mental ideas, including thinking, memory, imagination, and other faculties of the mind. In other words, perception extends to ideas, thoughts, consciousness, or mind. In fact, Berkeley specifically includes thinking with perception, “But my conceiving or imagining power does not extend beyond the possibility of real existence or perception. Hence, as it is impossible for me to see or feel anything without an actual sensation of that thing, so is it impossible for me to conceive in my thoughts any sensible thing or object distinct from the sensation or perception of it” (414). He further explains, “For the existence of an idea consists in being perceived” (413). For Berkeley, every thought, imagination, and memory, constitute perception and, further, all that one really has access to is idea or mental experience. The cognitive faculties of the mind—our images (including memory, imagination, or imaginary figures such as unicorns), concepts (conceptual truths such as mathematics and the laws of logic), and physical percepts all reside in the mind, and it is mental experience that is all one can know. All reality is ultimately reducible to mind or consciousness. Perception is mental experience and all reality equates to perception, “What do we perceive besides our own ideas or sensation” (413)? Accordingly, Berkeley insists that something must be perceived by the mind in order for it to be considered real, “It is indeed an opinion strangely prevailing amongst men, that houses, mountains, rivers, and in a word all sensible objects, have an existence, natural or real, distinct from their being perceived by the understanding” (414). For Berkeley, the individual perceiver is all-determining, since every thought, idea, and object is included in Berkeley’s definition of perception. This is Berkeley’s subjective idealism because all reality ultimately depends on the personal mental experiences of the perceiver.

Berkeley further explicates this notion with his famous phrase “esse is percepi”—to be is to be perceived, “For as to what is said of the absolute existence of unthinking things without any relation to their being perceived, that seems perfectly unintelligible. Their esse is percepi, nor is it possible they should have any existence out of the minds or thinking things which perceive them” (414). For Berkeley, the idea of an external reality that exists independently of the mind, or perception is conceptually incoherent. If a thing is not perceived, it does not exist. Essentially, Berkeley’s idealism follows this line of reasoning—all perceptions, concepts, and thoughts are ideas and can only exist in the mind. Therefore, everything exists only in minds. This does not mean, however, that something does not exist, or goes out of existence if it is not perceived or is no longer perceived. As an Anglican bishop, Berkeley believes God perceives everything and is the foundation of all reality. Because God perceives something, it is real and exists in reality (as part of God’s mind) even if no other individual is around to perceive it:

Such I take this important one to be, viz., that all the choir of heaven and furniture of the earth, in a word all those bodies which compose the mighty frame of the world, have not any subsistence without a mind, that their being is to be perceived or known; that consequently so long as they are not actually perceived by me, or do not exist in my mind or that of any other created spirit, they must either have no existence at all, or else subsist in the mind of some Eternal Spirit—it being perfectly unintelligible, and involving all the absurdity of abstraction, to attribute to any single part of them an existence independent of a spirit. (414)

In this manner, Berkeley suggests, as he does throughout his Principles of Knowledge, that he really does believe in an external reality because God or an Eternal Spirit perceives all things. For Berkeley, reality of a sort is possible and he narrowly escapes solipsism, which is often the end result of subjectivism. Nonetheless, all reality is fundamentally a mental perception or experience of the mind. For Berkeley, all reality is immaterial and ultimately exists in the mind of God.

As reality is not based on external matter, but on mind or a perceiving spirit, matter itself is illusory (429, 439-440). Only the most ignorant would believe that matter actually exists (423). In fact, Berkeley rejects the notion that a material world exists apart from mind, “But why should we trouble ourselves any farther, in discussing this material substratum or support of figure and motion, and other sensible qualities? Does it not suppose they have an existence without the mind? And is not this a direct repugnancy, and altogether inconceivable” (416)? Further, “The only thing whose existence we deny is that which philosophers call Matter or corporeal substance” (419).2 Berkeley posits that immaterial mind is the foundation of all reality. For Berkeley, if there is a conflict between mind and matter, the subjective and objective, or appearance and reality, all one needs to do is simply eliminate external material existence and the problem is solved. What is left is mind-dependent subjective appearance.

In the next post, we will explore why Berkeley thought it was important for something to be perceived in order to exist which is the point of contention for classical realists.

1Both idealism and realism show up in Western thought in various forms. The categorization of these thinkers is for the purpose of a general grouping while acknowledging that particular differences and emphases can be found in each individual thinker. Neither school is monochrome in its outlook.

2Italics in the original. It is not clear to which specific philosophers Berkeley is referring. However, it is likely he has something like Aristotle’s definition of substance as a combination of matter and form in view.

Works cited

Adler, Mortimer. Adler’s Philosophical Dictionary: 125 Key Terms for the Philosopher’s Lexicon. Scribner, 1995.

Berkeley, George. The Principles of Human Knowledge. Great Books of the Western World. Vol. 55. Encyclopedia Britannica, Inc., 1999.