Abstract

Aristotle usually has an extremely bad reputation as a physicist among scientists and historians of science. Central to this is the treatment of his version of the geocentric conception of the cosmos, according to which the earth is at the centre of the cosmos and does not move, and which was the dominant picture in antiquity and throughout the middle ages. Aristotle’s view is commonly regarded as a pernicious influence on the course of cosmology until the Renaissance, one which held sway only because of Aristotle’s authority. The chapter argues that his integration of astronomy and physics—his pursuit, in a variety of works written over a long period, of the question: ‘what does the world have to be like, in terms of a unified physics, if current astronomical theory is right?’—embodies a degree of comprehensiveness, sophistication, and elegance simply unparalleled in the ancient world. It is also more robust—given the astronomy of Aristotle’s day—than is usually thought: the chapter considers a number of difficulties it faced, and outlines responses which Aristotle either did make or could have made. The only serious rival to Aristotle’s astrophysics before Kepler and Newton was the theory set out in Ptolemy’s Planetary Hypotheses, which attempts to integrate physics with his astronomy: the chapter argues that for all its subtlety, this theory fares very poorly as a piece of physics. It was not, therefore, simple deference to authority which led some Islamic and Renaissance scientists to prefer Aristotle’s theory even though they could not see how to square it with Ptolemaic astronomy.