This book constitutes the first sustained, comprehensive, and rigorous critique of contemporary Hobbesian contractarianism as expounded in the work of Jean Hampton, Gregory Kavka, and David Gauthier. Professor Kraus argues that the attempts by these three philosophers to use Hobbes to answer current political and moral questions fail. The reasons why they fail are related to fundamental problems intrinsic to Hobbesian contractarianism: first, the problem of collective action arising out of the tension in Hobbes's theory between individual and collective rationality; second, the classical problem of explaining the normative force of hypothetical action, a problem that can be traced to the conflicting strategies of hypothetical justification found in Rawls's and Hobbes's theories. Given the deep interest in Hobbesian contractarianism among philosophers, political theorists, game theorists in economics and political science, and legal theorists, this book is likely to attract wide attention and infuse new life into the contractarian debate.