Anne Peterson

How should we understand the relationship, for Aristotle, between matter, form, and hylomorphic composite? Are matter and form distinct from each other, so that each hylomorphic unity harbours a plurality within it, or would such a plurality undermine the unity of the composite? A recent strand of argument in both Aristotelian and contemporary literature on hylomorphism has concluded that no genuine unity can be composed of a plurality. I will argue that the objection motivating this conclusion falls away as improperly formulated in light of Aristotle's metaontology—in particular, his thesis that unity is indeterminate. The genuine objection threatening hylomorphic unity is one that Aristotle himself formulates as a central concern in his Metaphysics: no substance can be composed of substances. He answers this genuine objection in his appeal to the actuality/potentiality distinction, and in Metaphysics VIII.6 he reminds us why no more basic problem of hylomorphic unity arises. Against the backdrop of Aristotle's metaontology, hylomorphic unity cannot be undermined by the plurality, just as such, of matter and form.

The traditional concept of prime matter – a purely potential substratum that persists through substantial change and serves to constitute the generated substance – has played a dwindling part in Aristotelian scholarship over the centuries. In medieval interpretations of Aristotle, prime matter was thought to play these two roles in all substantial changes, not only in changes at the level of the four elements. In more recent centuries, traditional prime matter was relegated only to the context of substantial changes between the four elements. And in the last few decades of Aristotelian scholarship, it has become common either to downplay or even to eliminate prime matter’s role in elemental changes too. I will support the traditional concept of prime matter by showing that it aligns Aristotle’s view of elemental change with one of the central constraints on matter imposed in his Physics to a degree that cannot be achieved on the non-traditional interpretations: the need for matter to be in potentiality in a way that avoids the two problematic extremes of mere persistence, on the one hand, and destruction, on the other. This point will be supported by Aristotle’s rejection of both monism and pluralism in On Generation and Corruption. Second, I will argue that Aristotle calls for precisely the same kind of potentiality in a very different context: his critique of Anaxagoras’s view of matter in the Generation of Animals. Here the very same problematic extremes of mere persistence and destruction that plague the alternate views to traditional prime matter also plague the dominant views on the matter for animal generation. Especially since Aristotle takes living things to be paradigmatic substances, these comparisons suggest that the apparent idiosyncrasies of elemental transformation which have motivated interpreters to depart from traditional prime matter may not be so idiosyncratic after all. And if that is so, it may be that the problem lies not so much with traditional prime matter as with our assumptions about how persistence and constitution work in substantial change according to Aristotle. In the end, this line of argument opens the door to three new potential interpretations of the matter for substantial generation in Aristotle, interpretations which align with his concept of potentiality and – to varying degrees – with traditional prime matter as well.