ABSTRACT
William Alston and Jonathan Bennett raise a puzzle that takes students right to the heart of John Locke's metaphysics, offer an ingenious and original solution to it, and they do it all in sparklingly clear philosophical prose. They claim that only atoms—or things more basic than atoms—will be basic in this sense, but in fact Lockean masses will qualify as well. They solve the puzzle about people and substances by saying that Locke takes people, organisms, and machines to be substances in the broad sense, but not in the narrower sense. Locke takes any change in the material constitution of a coherent group of atoms to be the end of one mass and the beginning of another, so no mass can possibly gain or lose parts. He may count collections, kinds, and stuffs as substances.
