Abstract

Chapters 10 and 11 are critical to the argument of Metaphysics Zeta: these chapters are concerned with the purification of form. Z.10 introduces the apparatus of part and whole and consists of an argument to the end that form and its parts have priority over the other internal structural components of c‐substances, i.e. matter and the compound of form and matter; while in Z.11 Aristotle argues that form and its parts cannot involve any admixture of matter. Wedin argues that the causal role of form presupposes its purity: if form is to explain why a certain portion of matter constitutes a c‐substance of a given kind, then matter—whether this latter is understood as functional, or remnant matter—cannot already be contained in the form. This is the ‘purity thesis’, as Wedin calls it: matter cannot be included in the definitions of natural organisms, Wedin points out, because that would make the explanandum a part of the principle that explains it. Wedin also argues that form must be sufficiently complex to provide definitions of the natures of particular compounds, which are complex, even though form itself is a kind of universal.