The philosophy of biology has considerable implications for our understanding of the kind of beings we are; perhaps because of this, it has been an area of rapid development and considerable controversy in recent years. This textbook offers an accessible guide to the traditional themes and the recent debates, assuming no prior training in philosophy or biology on the part of the reader. The central subject of the philosophy of biology is evolutionary theory. Professor Sober gives an account of the structure and explanatory significance of the theory, and considers the evidence for it; his discussion ranges over creationism, sociobiology, teleology and the issue of nature versus nurture.