This essay begins by approving Aristotle’s general argument for teleology in Physics II.8. It then explores his use of teleological explanations in the biological works, distinguishing his practice when actually giving explanations from his theory of how these explanations work. It is argued that while the practical instances usually make good sense, the theoretical explanation which identifies telos with form is wholly misleading. This brings the discussion back to the very puzzling chapter 9 of Physics II, and thence to a consideration of the idea that absolutely everything in nature is for some purpose. There are places where Aristotle seems to endorse this, although a more sober view would also assign a role to what may be called ‘laws of matter’, independent of teleology. The essay ends with some general reflections on Aristotle’s view of explanation in the natural sciences.
Keywords: Aristotle, Physics, biological works, form, teleology, necessity, nature, explanation, laws of nature