Abstract. Current teleology in Western biology, philosophy, and theology draws on resources from four main Western philosophers. (1) Plato's Timaeus shows how to interpret the universe as the handiwork of a purposive Creator who subordinates secondary, necessary, causes to primary, intelligent, causes. (2) Aristotle's Physics sets forth purpose as implicit in the nature of things. Purposes of different sorts inhere in different types of being, and everything has a natural function. Living things grow to actualize the potentials of the goal whose principle they bear within themselves. (3) Kant's Critique of Judgment denies that purpose is anything that human beings can know, strictly speaking. Nevertheless, purpose is a concept we must use to make sense of biological systems. (4) Hegel's Philosophy of Nature articulates organic systems as dialectically including and transcending mechanical and chemical systems. Teleological themes persist, in different ways, in contemporary discussions; I consider two lines of criticism of traditional teleology—by Richard Dawkins and Stephen Jay Gould—and one line that continues traditional teleology in an updated way—by Holmes Rolston, III.