아리스토텔레스 실체론의 지형도

Abstract

The central question in Aristotle's ontology is the following: "what is substance?" This question seems to be very simple. His answer is, however, so extensively embedded in the various contexts of his ontology that it might be hard to figure out it without properly examining them. If carefully examined, the main points might be made as follows. The simplest version of the Aristotelian theory of substance is found in the Categories in which Aristotle tries to classify predicates and beings. Here, the term "substance" means the first category of being and at the same time the beings that belong to the category: perceptible individuals such as “this man” or “this horse” on the one hand and universals such as man and animal that “are said of” the individuals on the other hand. The former are called primary substances and the latter secondary ones. This theory of substance is, above all, characterized by the assumption that the primary substance is the principle of other beings in the sense that those exist only with reference to the primary substance. Aristotle holds that only the primary substance exists separately and as "this", while the other beings either exist by being predicated of the primary substance as ultimate subject or by being inherent in it. This commonsensical theory of substance goes more deeper in the Metaphysics to the extent that the primary substance advanced in the Categories is analyzed into its two parts, i. e. matter and form, and their substantiality is brought into question. As for the matter, Aristotle does not hesitate to deny its status of substance. The matter, he argues, is the ultimate substrate but does not have other two characteristics of substance, i. e. separability and "thisness". So, he ascribes the status of substance only to the form which is separable and exists as "this": He calls it "primary substance" on the ground that it is the cause of being for the composite substance. In this context of the so-called hylemorphism, therefore, it turns out that there are three sorts of substance, namely, perceptible individuals, universals, and forms. Futhermore, the ontological priority is given to the form which causes indefinite matter to become a definite and composite substance of a certain kind. This account of form in the Metaphysics shows that it is the immanent and particular principle which is responsible not only for the individuality of the perceptible substance but also for its universal character. Another concept of substance we encounter in the Metaphysics expresses itself in the phrase "substance of each thing". It means neither any sort of substance advanced in the Categories nor the form but the essence of each thing. From the viewpoint of logos he defines the essence of each thing as "that which it is said in virtue of itself" and assumes that the essence primarily belongs to substances and secondly to other non-substantial beings. How precisely Aristotle's conceptions of essence are elaborated, there remains one crucial question unanswered: Is there also any essence of individual substance if the essence primarily belongs to substance, as he assumes? In Metaphysics VII Aristotle does not go into this question. However, he alludes in many passages in his Metaphysics to the essence of individual by using such expressions as "your essence" and "the essence of Callias". Maybe his suggestions about individual essences can be at best interpreted, based on the background of his theory of heredity in the De generatione animalium.