Christopher Byrne

In his metaphysics and natural philosophy, Aristotle uses the concept of a material cause,i.e., that from which something can be made or generated. This paper argues that Aristotle also has a concept of matter in the sense of physical stuff. Aristotle develops this concept of matter in the course of investigating the material causes of perceptible substances. Because of the requirements for change, locomotion, and the physical interaction of material objects, Aristotle holds that all perceptible substances must be extended in three dimensions, movable, and corporeal due to their material causes. Thus, perceptible substances are physical substances because they are made out of something physical.

According to a long interpretative tradition, Aristotle holds that the formal cause is the ultimate object of induction when investigating perceptible substances. For, the job of induction is to find the essential nature common to a set of individuals, and that nature is captured solely by their shared formal cause. Against this view, I argue that Aristotle understands perceptible individuals as irreducibly composite objects whose nature is constituted by both their formal and their material cause. As a result, when investigating perceptible objects, the job of induction is to discover their composite, formal and material nature. The process by which universal claims about this composite nature are justified, I argue, is similar to what we now know as mathematical induction. In particular, such claims are grounded in a non-enumerative, but replicable process in which things are resolved into their simplest components. As a result, the observation of past uniformities has, at most, a heuristic function in scientific inquiry.

Aristotle uses two kinds of material cause in his analysis of biological organisms: compositional matter, which persists through their birth and death;and functional matter, which consists of the organs and functional parts out of which biological organisms are made while they are alive. These two kinds of material cause, it has been argued, have quite different explanatory roles: functional matter is required by biological organisms to perform their essential functions,but compositional matter contributes nothing necessary to them and is only responsible for their accidental properties. Against this view, I argue that biological organisms are systematically dependent upon their compositional matter and the latter is responsible for many of their necessary attributes.