CATEGORY means a predicate. Now the predicate of an assertion is usually some class-name or concept under which the subject is brought, in the case of affirmative assertions, or from which the subject is excluded, in the case of negative assertions. In popular usage, accordingly, the term category is applied to any class or concept. Philosophically, however, the term category is confined to ultimate modes of being, or to the ultimate concepts or modes of apprehension by which reality is known. The first systematic account of categories was given by Aristotle. His account held the field for many centuries. Its most serious com petitor in the history of philosophy is the account given by Kant. But although the general orientation of the two philosophers was very different, yet their lists of categories are remarkably similar when due allowance is made for their difference in philosophical standpoint.
Aristotle's Account of the Categories.—This is contained partly in the treatise of that name which forms the first of the collection of logical treatises known as the Organon, and partly in the Metaphysics. Aristotle assumed that our ultimate modes of apprehending reality correspond to ultimate modes of being. Like most pre-Kantian philosophers who were not sceptics Aris totle did not seriously consider the possibility that reality may not be in itself what it is perceived or conceived to be. The Aris totelian categories were accordingly regarded by him as expressing at once ultimate modes of being and ultimate modes of apprehen sion (or predication) . His list of categories was as follows (the Latin and English equivalents are added for convenience).
okia substantia substance iroTE quando time 7rocr6v quantitas quantity stacr6at sit/is (or situa tion) 7r ocov qualitas quality fXecv habitus state (or condition) rpor TL relatio relation roceiv act%o activity irov ubi place 7raQXecv passio passivity (or being acted on) How exactly Aristotle arrived at his scheme of ten categories is not known. It has been suggested that he was guided by familiar grammatical distinctions—nouns, adjectives of quantity and of quality, adverbs of place and of time, the active and the passive voice of verbs, and so on. But there is no real evidence of this contention. A certain degree of correspondence between categories and grammatical distinctions would be inevitable in any case, seeing that distinctions in thought naturally find expression in linguistic differences.
In order to understand the Aristotelian list of categories one must be clear about the meaning of "ultimate modes of being" which they were intended to express. J. S. Mill was under the impression that the list was intended to be a table of classification of all nameable things, and consequently criticized it as at once defective in some respects and redundant in others. But that was a misconception. To be a "thing" is only one "mode of being," namely, that of "substance," in the Aristotelian list. But the same concrete reality can embody many or all modes of being. Of Aristotle, for instance, one can predicate that he was a man (sub stance) who lived in Athens (place) in the 4th century B.C. (time), taught philosophy (activity), was accused of atheism (passivity), felt depressed (state), fled to friends (relation), and so on. A classification of "things" would be bad if it included the same object (say, Aristotle) in several classes at once. But it is quite different with "modes of being." Several or all ultimate modes of being may, and do, exist in the same concrete individual, and yet such mode of being may be quite distinct from, and irreducible to, any other. To be a "thing" is different from being a "quantity" or "quality," etc., and none of them can be made intelligible by reference to the other. The predicate "green" may be explained by reference to "colour," and "colour" may be explained by refer ence to "quality"; but "quality" itself cannot be usefully ex plained by reference to any other term, but is ultimate in this sense. Similarly with the other categories—they were all intended to express ultimate modes (or summa genera) of being, and there fore of predication.
Aristotle himself did not regard his ten categories as of equal importance. It is clear that he regarded substance as, in a sense, the most fundamental category, inasmuch as quantity, quality, etc., can only exist in substances. Hence the Scholastic, Cartesian and Spinozistic distinction between Substance and Accidens (or Mode), between that which exists by itself and that which only exists in another. Curiously enough recent thought has tended more and more to discard the category of substance altogether (see SUBSTANCE) in favour of a world of "events" in space-time. There is also a tendency to discard the categories of activity and passivity or at least to reduce them to that of quantity (see CAUSALITY). Kant's Account of the Categories.—This is most intimately connected with his "critical" standpoint, and constitutes the very core of his philosophy. Kant dismisses the idea that we can have knowledge of things as they are in themselves (noumena), and he confines human knowledge to phenomena, that is, to appear ances of the real rather than to the inner being of it. This stand point involves jettisoning of one side of the doctrine of the cate gories as taught by Aristotle, namely, the claim that they repre sent ultimate modes of being. From Kant's point of view the enquiry must confine itself to ultimate modes of human appre hension or forms of synthesis. Now Kant held that in all so-called human knowledge certain raw materials are supplied from out side, but that they are worked up, as it were, by certain forms of apprehension which are inherent in the human mind (see A PRIORI), and he distinguished two groups of such forms of syn thesis. In one group he placed space and time, which he regarded as forms of synthesis involved already in the very possibility of apprehending things at all in sense-perception. They are forms of sense-apprehension or perception (as distinguished from forms of thought). In the other group he placed the categories or forms of thought. This restriction of the term category to a mode of thought as distinguished from any other mode of apprehension is peculiar to Kant. Aristotle made no such distinction, and using the term category in the Aristotelian sense, it may be said that Kant recognized the Aristotelian categories of space and time, at least as modes of predication. In Kant's special sense, however, the categories are forms of conceptual or intellectual synthesis. Now judgment is the same as thought or understanding. The ultimately different forms of judgment should consequently ex press the ultimately different kinds of synthesis of the under standing. Kant accordingly derived his list of categories from the different forms of judgment. But instead of critically determining first what the altimate forms of judgment are he took over from formal logic the usually recognized list with just a little further elaboration or over-elaboration. His result is represented in the following table which gives the Kantian categories together with the various forms of judgment to which they severally correspond. It will be observed that they are grouped into four principal classes with three divisions in each.
