Change, motion, and explanation › Purpose without deliberation

Aristotle's natural teleology claims that some natural processes occur for the sake of ends. This does not mean that a plant thinks about what it wants to become. In II.8 he argues that the absence of deliberation does not rule out end-directed activity. His comparison with craft concerns the organization of a process toward a result, not a conscious plan inside every growing thing.

He presents a serious alternative. Perhaps useful arrangements arise through material necessity, and the arrangements that happen to work persist. The example concerns teeth: sharp front teeth tear food while broad molars grind it. Why not regard their usefulness as a fortunate result rather than their explanatory end? Aristotle answers by appealing to the regularity of such natural arrangements and their organized development (Physics II.8).

A reader can dispute that inference. Regular outcomes might require explanation without establishing the particular final-cause account Aristotle favours. The alternative he presents is worth reading carefully, but we should not equate its brief ancient formulation with a complete modern evolutionary theory. The chapter can identify the explanatory issue without claiming that Aristotle anticipated or refuted a later science.

Material necessity still matters in Aristotle's own account. In II.9 he asks what conditions are necessary if an end is to be realized. A saw must have appropriate material if it is to perform its work. Specifying what the tool is for does not make any material adequate. Conversely, listing its material properties does not by itself specify its function. The point is the relation between an end and the conditions required for it, not permission to ignore mechanisms.