The Categories (Lat. Categoriae, Greek Κατηγορίαι Katēgoriai) is a work by Aristotle that aims to categorise all the possible sorts of thing which can be the subject or the predicate of a proposition. It is part of a collection of treatises now called the Organon, which comprise all of his works on Logic.
The word 'category' (Latin praedicamentum) is from the Greek word for 'predicate'. A category is whatever can be expressed without composition. According to Aristotle, there are only ten kinds of thing that can be predicated. Thus the Categories places every possible thing that can be thought under one of these ten categories (known to medieval writers as the praedicamenta or generalissima).
The text begins with an explanation of "synonymous," or univocal words, what is meant by "homonymous," or equivocal words, and what is meant by "paronymous," or denominative words. Language is either simple, without composition or structure, such as "man," "horse," "fights," etc., or it has composition and structure, such as "a man fights," "the horse runs," etc. Next, he distinguishes between a subject of predication, namely that of which anything is affirmed or denied, and a subject of inhesion. A thing is said to be inherent in a subject, when, though it is not a part of the subject, it cannot possibly exist without it, e.g., shape in a thing having a shape.
Of all the things that exist,
- Some may be predicated of a subject, but are in no subject; as "man" may be predicated of James or John, but is not in any subject.
- Some are in a subject, but can be predicated of no subject. Thus my knowledge of grammar is in me as its subject, but it can be predicated of no subject; because it is an individual thing.
- Some are both in a subject, and may be predicated of a subject, such as knowledge, which is in the mind as its subject, and may be predicated of geometry.
- Some things can neither be in a subject nor be predicated of any subject. These are individual substances, which cannot be predicated, because they are individuals; and cannot be in a subject, because they are substances.
Then we come to the categories themselves, (1)-(4) above being called by the scholastics the antepraedicamenta. Note, however, that although Aristotle apparently distinguished between being in a subject, and being predicated truly of a subject, in the Prior Analytics these are treated as synonymous. This has caused some to suggest that Aristotle was not the author of the Categories.
The ten categories, or classes, are
- Substance. As mentioned above the notion of "substance" is defined as that which can be said to be predicated of nothing nor be said to be within anything. Hence, "this particular man" or "that particular tree" are substances. Later in the text, Aristotle calls these particulars "primary substances," to distinguish them from "secondary substances," which are universals. Hence, "Socrates" is a primary Substance, while "man" is a secondary substance.
- Quantity. This is the spatial extension of an object. All medieval discussions about the nature of the continuum, of the infinite and the infinitely divisible, are a long footnote to this text. It is of great importance in the development of mathematical ideas in the medieval and late scholastic period.
- Quality This is a determination which characterizes the nature of an object.
- Relation This is the way in which one object may be related to another.
- Place Position in relation to the surrounding environment.
- Time Position in relation to the course of events.
- Position The examples Aristotle gives indicate that he meant a condition of rest resulting from an action: ‘Lying’, ‘sitting’. Thus position may be taken as the end point for the corresponding action. The term is, however, frequently taken to mean the relative position of the parts of an object (usually a living object), given that the position of the parts is inseparable from the state of rest implied.
- State The examples Aristotle gives indicate that he meant a condition of rest resulting from an affection (i.e. being acted on): ‘shod’, ‘armed’. The term is, however, frequently taken to mean the determination arising from the physical accoutrements of an object: one's shoes, one's arms, etc.
- Action The production of change in some other object.
- Affection The reception of change from some other object. It is also known as passivity. It is clear from the examples Aristotle gave for action and for affection that action is to affection as the active voice is to the passive. Thus for action he gave the example, ‘to lance’, ‘to cauterize’; for affection, ‘to be lanced’, ‘to be cauterized.’ The term is frequently misinterpreted to mean a kind of emotion or passion.
The first six are given a detailed treatment in four chapters, the last four are passed over lightly, as being clear in themselves. Later texts by scholastic philosophers also reflect this disparity of treatment.
After discussing the categories, four ways are given in which things may be considered contrary to one another. Next, the work discusses five senses wherein a thing may be considered prior to another, followed by a short section on simultaneity. Six forms of movement are then defined: generation, destruction, increase, diminution, alteration, and change of place. The work ends with a brief consideration of the word 'have' and its usage.