Contemporary discussions of the success of science often invoke an ancient metaphor from Plato\u27s Phaedrus: successful theories should carve nature at its joints. But is nature really jointed ? Are there natural kinds of things around which our theories cut? The essays in this volume offer reflections by a distinguished group of philosophers on a series of intertwined issues in the metaphysics and epistemology of classification. The contributors consider such topics as the relevance of natural kinds in inductive inference; the role of natural kinds in natural laws; the nature of fundamental properties; the naturalness of boundaries; the metaphysics and epistemology of biological kinds; and the relevance of biological kinds to certain q...