On Existence and Substance

This last weekend I picked up Thomas Aquinas, De Ente et Essentia, on the hunch that somehow it would be relevant to what I had been thinking about. I confess that I hadn't understood before the significance of this book, since I had in a fairly foolish way allowed myself to get misled by the common translation of the title (On Being and Essence).

This time I was astonished to find that Aquinas uses ens for o)/n, and essentia for ou)si/a. A scholar of Greek philosophy, then, would wish to understand the title as, "On Existence and Substance", or, perhaps, "On Being and Substantial Being".

When its theme is understood in that way, the opuscula acquires the appearance of, in effect, a brief and elegant commentary on Z and its relation to L. Furthermore, it is a commentary which is enlightening insofar as it builds on a tradition very different from ours, that is, the tradition of Arabic commentators.

I want to share with you an interesting argument from its beginning.

The opening chapter of Z, as you know, seems simply to repeat doctrine about the priority of substance among the categories. It is a puzzle, I think, how this chapter relates to the rest of the book, and I think it is fair to say that most commentators today treat Z as if it begins with chapter 3. Burnyeat for instance, although he comments on ch. 1, says that the chapter merely directs us to what sort of being should be the principal object of the following investigation, namely, 'substantial being': "The chapter explains why a treatise on being should concentrate on primary being" (Map 12).

Yet Aquinas in De Ente et Essentia thinks that there is an important argument implicit in Aristotle's opening appeal to the categories. On Aquinas' reading, this argument sets the direction for the investigations of Z and, indeed, even helps to explain what I've been wondering about, viz. precisely on what grounds perceptible substances are given so much attention in Z.

I've whet your curiosity, I hope. In a subsequent post, I'll say what that argument is.