In this original and important book, Harold Kincaid defends a view of the special sciences-all sciences outside physics-as autonomous and nonreducible. He argues that the biological and social sciences provide explanations that cannot be captured by explanations at the level of their constituent parts, and yet that this does not commit us to mysterious, nonphysical entitites like vital forces or group minds. A look at real scientific practice shows that the many different sciences can be unified in a way that leaves them each an autonomous explanatory role. This book will be of great interest to philosophers of science and social scientists.