Sameness, Definition, and Essence

Abstract

I formulate an apparent inconsistency between some claims Aristotle makes in his Metaphysics about the sameness and non-sameness relations which obtain between an object and its essence: while a (type of) object is not the same as its essence, an essence is thought as being the same as its essence. I discuss different ways in which one may propose to overcome this apparent inconsistency and show that they are problematic. My diagnosis of the problem is that all these putative solutions share the assumption that Aristotle is operating exclusively with the notion of strict numerical identity between an object and its essence, or between definiendum and definiens. I introduce the notion of sameness in nature which holds between an object and its essence, understood as the metaphysical counterpart to the relation of 'being defined as': two items are the same in nature just in case the answer to the 'what is it?' or 'what is its nature/essence?' question is common to both. I argue that the notions of sameness in nature and 'being defined as' need not (but may) entail strict identity. Further, they are compatible with, indeed require, the idea that an essence is prior to its essence-bearer, or that a definiens is prior to the relevant definiendum. I conclude that the twin notions of sameness in nature and 'being defined as' successfully defuse the apparent inconsistency formulated at the outset.

Aristotle on the Relation between Substance and Essence

“…Hence, the essence is causally more basic than or ontologically prior to the substance. Therefore, since nothing is ontologically prior to itself, a substance cannot be identical with its essence (Charles 2011: 152;Peramatzis 2011: 4;2014;2015: 203-7). Or rather, it may be true that some substances are identical with their essences, namely, forms, but it cannot be generally true that substances 22 See Peramatzis 2014: 159-60 for a discussion of ways of being in this context.…”

“…In a series of papers, Norman Dahl (1997;1999;2003;2007) has developed a careful reading of Z.6 aimed at showing that the Z.6 claim is formulated in terms of sameness in formula or substance. Similarly, David Charles (2011: 153-54) and Michail Peramatzis (2011: 4-5;2014;2015: 203-7) contend that Z.6 concludes merely that each substance is the same in nature or definition as its essence, even though, according to Peramatzis, sameness in nature implies identity in the case of forms and their essences. Finally, Mary Louise Gill (2006: 358-59) has claimed that each substance is the same as its essence in the sense that the essence exhausts what the substance is.…”