Abstract: In this chapter, Hankinson examines Aristotle's philosophy of science, or the logical structure of explanation as set out in the Posterior Analytics, and which is based on the theory of the syllogism worked out in the Prior Analytics. For Aristotle, definition is fundamental to the project of exhibiting science in its appropriate explanatory form, i.e. proceeding deductively from fundamental principles and axioms about the structure of things. Science and scientific explanation are for Aristotle construed realistically: science must mirror reality, and therefore theory always must cohere with observation and empirical investigation. Hankinson discusses Aristotle's qualitative physics of motion, on the basis of the doctrine of natural places, his account of chemical combination, and his cosmology, which is at once teleological in character, while being empirically adequate. Hankinson also discusses Aristotle's successors Theophrastus and Strato of Lampsacus: Theophrastus developed and refined Aristotle's methodology while bringing some scepticism to the ubiquitous application of teleology; Strato also tends more towards mechanistic explanations.

Keywords: cosmology, definition, observation, philosophy of science, Posterior Analytics, Prior Analytics, Strato of Lampsacus, Theophrastus, theory,