In Aristotle's terminology, ousia, or substance, is that which is the subject of predication, but never itself predicated of anything. This is a highly technical definition; I don't expect it reflects the ordinary use of the word in ancient Greece.

Did Aristotle arrive at this definition by considering and refining the ordinary use of the word?* Or is it a purely technical definition which he simply introduces?

If his definition is purely technical, how does Aristotle's use of the word compare to its ordinary use in his society?

*As is his wont. As I understand his notion of science, we start with ordinary use/reputable beliefs that can distinguish between different kinds of things but do not tell us why things are different. Then we go through puzzles until we have a definition that does tell us why a given thing is that sort of thing. Then we have arrived at the starting point for a science.

  • On the pre-Aristotelian history (in Ancient Greek phil) of the terms regarding being (εἶναι and its nominal form οὐσία) see : Charles Kahn, Essays on Being, Oxford University Press (2009). Commented Jun 14, 2018 at 10:54
  • See Plato, Phaedo, 65d13, speaking of "absolute beauty and goodness” : "καὶ τῶν ἄλλων ἑνὶ λόγῳ ἁπάντων τῆς οὐσίας ὃ" (English : "I am speaking of all such things, as size, health, strength, and in short the essence"). Commented Jun 14, 2018 at 11:00
  • From what I understand Aristotle took the most basic traits of language as reflecting the most basic traits of being, and "derived" his list of categories by classifying forms of judgment in his syllogistic, subjects and predicates became substances and qualities, etc. Hence the semantic flavor of the "definition". Kant later followed with his "categories of understanding", but to him they mirrored our own faculties rather than reality, see How does Kant derive the categories of the understanding from the logical forms of judgment?
    – Conifold
    Commented Jun 14, 2018 at 23:20

1 Answer 1


'Did Aristotle arrive at this definition by considering and refining the ordinary use of the word? Or is it a purely technical definition which he simply introduces?' This extract from Michael Loux might help. Loux suggests, and supports the claim with argument, that Aristotle did not give ousia his own technical meaning. He seems to take the term as used (or as he understood it to be used) by predecessors such as Democritus and Plato. His novelty is to offer new criteria for what counts as ousia. (Compare in later philosophy how, say, Descartes, F.H. Bradley and Russell, don't disagree on what 'truth' means and none of them wants to give it a technical definition but they disagree over the criteria of truth - over what conditions have to be satisfied for a proposition to be true.)

WHATEVER novelty he may have claimed for his own answer to the question "Which things are ousiai?", Aristotle viewed his attempt to formulate a response to that question as continuous with the inquiries of earlier thinkers; and this suggests that the sense he attached to the term ousia is such that philosophers as different as Plato, Democritus, and Aristotle himself can all be said to be attempting an identification of ousiai. That Aristotle construed the term as neutral between opposing ontologies is clear from the early chapters o? Metaphysics Z;1 and unless we make this assumption, many of the ensuing chapters of Z and H are likely to remain a mystery. Recent tendencies to translate ousia as it occurs in the middle books of the Metaphysics in terms of the expression "reality" rather than in the more traditional ways as "substance" reflect a sensitivity to this point. But while the picture of a subject of or a thing standing under other things plays a more central role in the Categories than in the middle books, it is, nonetheless, misleading to read this picture into our translation of ousia as it occurs in the earlier work; for even there the term has a sense that is independent of the famous formula of 2a 11-12 ("neither said of a subject nor present in a subject"). That formula does not represent the attempt to stipulate a sense for a technical term which Aristotle wants idiosyncratically to introduce; it is rather the attempt to provide a criterion for identifying the things he takes to be the best candidates for an antecedently understood title. Thus, at 2a 33-2b 6 we find Aristotle effectively arguing that the things picked out by the formula actually deserve the title ousia, a procedure pretty clearly inappropriate in the case of a stipulated definition of a technical term. But what sense did he attach to the title? In part, he must have taken its derivation from the verb einai as explicative of its sense. In part too, he must have viewed its occasional use in Plato to express the idea of an ontologically privileged entity as precedent for his own use. Finally, there is the argument of 2a 33-2b 6, where Aristotle suggests that a minimal condition on any attempt to identify things worthy of the title prote ousia is that the items so identified constitute the smallest set such that we can truly say of the members of that set, "If none of these things existed, nothing else would either." (Michael Loux, 'Ousia: A Prolegomenon to Metaphysics Z and H', History of Philosophy Quarterly, Vol. 1, No. 3 (Jul., 1984), pp. 241-265 : 241.)


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