25 April 2006

Two Arguments from the Categories

Yesterday I considered the suggestion that the key question of Metaphysics Z is not, as is commonly held, "What is substance (ousia)?" but rather "What makes something such that it can be sorted?" --it being supposed that ousia does this.

I took this suggestion from Aquinas' De Ente et Essentia, approaching that work as a brief commentary on Z and Lambda. One advantage of this interpretation, I pointed out, is that it seems to make good sense of the topics actually considered in Z.

Yesterday I also noted that Aquinas thinks that Aristotle arrives at this question through a consideration of the categories. Now there would seem to be two ways in which one could take the categories to lead to the investigation of Z so conceived.

The first way, one might say, is from the very fact that there are categories; the second is from the priority of one category over the others.

The first way is what, it seemed to me, Aquinas was proposing in De Ente et Essentia. I gave a formulation yesterday, but here is another way of putting it:

We seem to incapable of considering that something exists, without supposing that it exists in one of the categories. We cannot even entertain the existence of something, without first thus classifying it. For instance, to consider the height of a horse, is already to be considering something distinct from the color of the horse. We couldn't be confused about whether we were investigating a quantity as opposed to a quality of the horse. This suggests that there is a deep connection between asserting the existence of a thing, and classifying it. We might then conclude that to assert the existence of a thing, just is to say that there is something about it such that it can be classified. Call this its ousia.

I asked whether there was warrant in Z1 for attributing an argument like this to Aristotle. After looking again at the chapter with this question in mind, I do not think that there is (although please feel free to disagree with me from your own examination of the chapter).

What I do find warrant for attributing to Aristotle, in Z1, is the following argument, which seems different from what Aquinas proposes. This argument hinges, not on the mere fact of the categories, but on the priority which the category named ousia enjoys relative to the others. This argument would proceed as follows.

To ask what ousia is, is to ask what truly or really (ontws) exists. We may understand this as: what especially (malista) exists. Let us approach this question through a consideration of the categories, since these involve predications of what 'is'. We see in that case that, although there are ten categories, the category of ousia is prior. In fact it is prior in all the ways in which one might wish to assert priority (as Z1 takes pains to observe). Thus ousia especially exists. However, a predicate which identifies the ousia of a thing tells us what, that is, what sort, it is (1028a14-18). Thus, what really exists is what makes a thing such that it can be sorted. To inquire into ousia, then, is to inquire into what it is about a thing which makes it such that it can be sorted. (And thus follows the investigation of Z.)

This latter argument does seem to me to be Aristotle's and to be found in Z1.

And this seems to me the correct way of approaching Z.