Protreptikos, Vol. 1, no. 4, a publication of Introduction to Philosophy
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Philosophy and Knowledge

Mind and Reality

The question of the relation of Mind and Reality belongs to the branch of philosophy variously called epistemology, theory of knowledge or gnoseology. In classical philosophy, one of the purposes of this branch is to answer the objections of those who say that knowledge of the real world is impossible. We have already looked at first principles of reason. These principles are self-evident. They cannot be proved, but must be assumed if any proof has validity. Even the sceptic who tries to say all knowledge is impossible, or that there is no truth, relies on these principles.

The classical definition of truth is a correspondence of mind and thing (adaequatio mentis et rei). This does not mean that truth in the human mind perfectly matches things in themselves. We do not know any real thing perfectly, in all its nature, but only selected details. The only thing that we can know perfectly is something that only has existence in our mind, such a mathematical formula. The classical definition means that we only grasp certain aspects of real things. However, that is still truth, because even if we only know aspects, that we know is either true or false.

Signs: Natural and Conventional

A sign is something that directs our attention to something other than itself. A natural sign is something that does this by its very nature. A conventional sign has meaning only by an arbitrary human decision. A basic kind of natural sign is simply based on cause and effect. If you see smoke, then your mind is directed to fire. If you hear a bird-song, you think of a bird. An example of a conventional sign would a letter of the alphabet as the sign of a sound, or a yellow triangle meaning "yield", or the spoken word in any language. All human language is a collection of conventional signs. Even so-called body language has different meanings in different cultures. Between a spoken or written word as a conventional sign, and the thing that the word designates, there is an intermediate sign, which is the concept in the mind of the speaker and in the mind of the person listening. Is a concept a conventional sign or a natural one? Aristotle taught that the first level of signs in language is the concept, which he called a passion of the soul. We might call a concept something that happens to the mind. He taught that the concept as a sign is common to all men. The spoken word is a sign of the concept, but the spoken word is not the same for all men. Rather, the spoken word is assigned by human convention.(1) Because of the close psychological connection between words and concepts, later philosophers called a concept an inner word. This is not just the sound of the word that we form in our mind when we are preparing to speak, but it is the meaning of the word as it exists in our mind. One of the chief arguments of sceptics is that what we know are concepts, but concepts are in the mind, and so our knowledge is not about things in reality. A concept, however, is a transparent sign, which means that it directs our attention to things without calling attention to itself. We know things through concepts, but concepts themselves are not directly the objects of our knowledge. They become objects of knowledge only when we reflect on our own acts of knowing.

Univocity, Equivocity, and Analogy

Words are signs of concepts, and concepts are signs of things. Words, concepts, and things are related in three fundamental ways. Univocity means that a word always has the same meaning. A univocal word is unambiguous and precise. Truly univocal words are general or universal. This means that they apply to any individual that belongs to a general class of things that share the same nature. Terms that can be applied univocally fall into one of five groups:

  1. Genus, or general kind ( e.g. Man is an animal.);
  2. Species, or specific kind (John is a man.)
  3. Specific difference, the special quality that sets one species or kind of thing apart from all other members of the same general group (man is a rational animal.),
  4. Property, a secondary feature that belongs to every member of a particular kind of thing (man is a risible animal),
  5. Accident, a feature that may or may not belong to a member of a given species (this man is fifty years old.)
The terms used by science are univocal, and much effort is devoted to formulating precise definitions of new terms.

Equivocal words are words that are the same with regard to the conventional sign used, such as the written word "date", but the same sign is used with completely different meanings about different things. For example, "to go on a date", "to buy dates at the grocery store". Sometimes, the two meanings of the same word are connected by some metaphor that does not touch the nature of the things.

Analogical words are words that do not have exactly the same meaning in each case, but neither do they have a completely different meaning.(2) There are two different structures of analogy. The Analogy of Attribution is when many things share the same name because they are related to one thing. For example, a urine sample, a complexion, a clean environment, and exercise are all called healthy because they are all related to one thing, which is health, either causing health or caused by health. This sort of analogy is in relation to one (pros hen - pros <en). The other structure is called Analogy of Proportionality, where two sets of relations are similar, but there is no one common thing. For example, as hearing is to the ear, so sight is to the eye, and so understanding is to the mind.

In classical philosophy, we are dealing with many concepts that apply to all of reality, but which are very difficult to define. These are analogical concepts. Usually they are numbered as seven:

  1. being,
  2. one (unit - unity),
  3. thing,
  4. something (something else, distinct from others),
  5. true,
  6. good,
  7. beautiful
. Whereas univocal concepts apply to one class and can be defined, these concepts are called transcendental concepts, or simply transcendentals.(3) This means that they cut across or pass over all the boundaries between different kinds of things, and apply to anything that really exists. Universal concepts are abstract, because our concept of a species is not an idea of any particular existing individual, but only the essential features that belong to any member of the species. A transcendental concept is not abstract, because we are turning our attention to the real thing, the thing that exists, which is unique, unrepeatable. Anything which exists is a being, is a unity in itself, an intelligible thing, distinct from other things, a true thing, a good thing, and a beautiful or itneresting thing. The first 4 transcendentals focus on being itself, and the last three focus on being in relation to the mind and will. Also, the transcendentals admit of degrees. Things have more or less existence, more or less unity, are more or less distinct from other things, and the same with truth, goodness and beauty.

Some analogical relations are based on a similarity that comes from a common cause. One philosophical axiom is that every efficient cause causes something similar to itself (omne agens agit sibi simile). A cause gives to the effect something of itself. Another saying is that no one can give that which he does not have (nemo dat quod non habet). We can see this in things that we make. If I build something, then it is because I already possess the idea within myself. I am giving shape to something that is already inside of me. The idea itself in my mind is called the exemplar cause of the product; it may also be called a model or paradigm. An exemplar cause is like the form of a thing existing outside of the thing. Thomas Aquinas' fourth argument for the existence of God is based on the analogy of being.(4) He recognizes that there are different degrees of being, unity, goodness, and so on, in the things that we see. They must be related to something which has maximum being, goodness, beauty and so on.

The concepts of being, unity, truth and so forth were not invented by philosophers. Every human being understands them. Aquinas rightly teaches that being is what the mind first knows. Before we are able to define the different kinds of things in the world, we know that there real things, what it is to exist, that things are separate unities. At the very beginning of our experience, we understand being, the transcendental concepts, and the first principles, although we are not able to clearly express this knowledge. Philosophy is based on these primary truths, so philosophical arguments do not depend on the progress of science for their validity.

Ens Reale and Ens Rationis

Real Being and Mental Being

A species, genus, or specific difference exists as a unity only in the human mind. In reality, only singular concrete things exist. For example, when a biologist talks about the mammal, or a chemist about the oxygen atom, they are talking in general terms. Meanwhile, no two mammals are alike, and no two oxygen atoms are absolutely alike (or they would be the same atom). What exists as a unity in the human mind, exists as many in reality. "Oxygen" and "Mammal" are words that have real meaning, but that "meaning" in reality exists in many individuals. The difference between how things exist in reality, and how they are represented in our mind, has led to the controversy over universals in the fourteenth century. This controversy is by no means over. The whole history of philosophy can be described in terms of this controversy, with Extreme Realism (that ideas are real, reality exists in the same way we understand it, individuals do not have full existence), Nominalism (only individuals exist, and our concepts and words are empty), and Moderate Realism (ideas correspond to reality, but natures exist only in concrete individuals).

Extreme Realism

Parmenides, Plato, Descartes, Kant

Extreme realism is also intellectualism. It is the position that our intellectual knowledge is the only road to understand the true reality. Parmenides was perhaps the first in this group. He reasoned that there is only being, there is no non-being. There can only be one being, and even our thought of being, and being itself must be identical. Plato (428-328 B.C) taught that ideas are permanent and true realities, and the things that appear to our senses are only like shadows of the ideas. True knowledge is obtained by escaping from the deception of the senses. He illustrates this doctrine with his allegory of the cave.(5) A much later philosopher, René Descartes (1596-1650), wanted to found philosophy and all the sciences on "the clear and distinct idea".(6) For Descartes, the clarity of an idea was a sign of its truth, and he developed a method called "the method doubt". Even if something agreed with common sense, if it could possibly be doubted, if it was vague and hard to define, then it should be rejected. In his system, the clearest and absolutely irrefutable idea is "I think, therefore I am". The existence of the self is the undisputable first truth of Cartesianism (as the philosophy of Descartes is called). Descartes started what is called the philosophy of the subject, which considers the view that there is a real world to be naive. Immanuel Kant (1724-1804) continued along the same lines.(7) According to Kant, we can't know reality as it is, but we can know the thought structures of our own mind, which we impose on our sense experience to make it meaningful. These psychological structures are called a priori categories.


Only Individuals Exist

Nominalism is the doctrine that only individuals exist, and that terms that indicate a general nature have no meaning. Nominalism accents sense knowledge, because everything that appears to our senses is an individual, and rejects intellectual knowledge and abstraction. William of Occam in the 1300s was the major exponent of nominalism. He said that a general term was a meaningless sound (a wind of the voice -- flatus vocis). Nominalism is repeated in the philosophy of Thomas Hobbes (1588-1679), John Locke (1632-1704), George Berkeley (1685-1753), David Hume (1711-1776), John Stuart Mill (1806-1873), and many modern philosophers. Jean Paul Sartre (1905-1980)is close to the nominalist position. Sartre's expression was that existence precedes essence. He adopted an atheist position, and concluded that if there is no God there is no such a thing as nature. Therefore, the human mind imposes the idea of nature on reality, which by itself is meaningless.(8)

In ethics, nominalism has several consequences. If there are no natures of things, then it is up to man to formulate norms. Thomas Hobbes argued for dictatorship from a nominalist position. If there was nothing in man's nature that indicates right or wrong, then man's survival would best be served by a strong monarch would would prevent people from acting too much in their own advantage. Also, if only individuals exist, and there is no nature, then there can be no universal principles, but each and every situation will be radically different. Situation ethics, which emphasizes sensitivity to each unique situation, and rejects universal moral norms, is rooted in nominalism.

Moderate Realism

Moderate realism is the just mean between extreme realism and nominalism. It distinguishes between the thing itself with the way it exists. A thing exists in the mind as a universal (universal concept), and in reality it exists as an individual. What our ideas present to us in a universal does not exist outside the mind as a universal, but as an individual. Human nature is a reality, but it is the reality in the existence of individual human beings, not as a separate entity. Moderate realism is the position of Aristotle, Aquinas and such modern philosophers as Jacques Maritain and Etienne Gilson. Moderate realism recognizes both sense knowledge, which presents things in their individuality, and intellectual conceptual knowledge, which presents things in their nature.

In ethics, moderate realism recognizes a natural law, based on the constants of human nature, as well as the need to apply the law with discretion according to the particular situation (this application is called epikeia).


1. Aristotle in Peri Hermeneias, (On Interpretation) I, i, 16a. Also, Aquinas Exposition of St. John's Gospel, c. 1, lect. 1, in Bourke, p. 23-24.

2. Aquinas discusses analogy: The Principles of Nature, (Bourke p. 75-76); Summa Theologica, I, q. 13, a. 5, c. (Bourke 164-165); On the Trinity, I, 9, c (Bourke 165-166); On Truth, II, 11, c. (Bourke 166-168). See also Vaske, On Being Human, p. 12

3. The transcendentals are discussed in the following passages by Aquinas (Bourke page numbers in parentheses): On the Power of God, IX, 7, ad 6 (p. 160); Summa Theologiae, I, q. 5, ad 1 (p. 161); On the Virtues, 2, (p. 210-211).

4. Summa Theologica, I, q.1, a. 3 (Stumpf, p. 379-381).

5. Plato's Republic, (Stumpf, p. 251-268).

6. See Stumpf, p. 268-286.

7. Kant, Critique of Pure Reason, in Stumpf, p. 304-308.

8. Jean Paul Sartre, The Humanism of Existentialism, (Stumpf, p. 571-577).