The idea that a political order derives its authority, legitimacy, and justification from some kind of initial agreement or contract, whether hypothetical or tacit, has been a mainstay of political philosophy, at least since Hobbes. Today, the leading approach to theorizing justice–John Rawls’ conception of “justice as fairness”– employs a contract doctrine, albeit of a somewhat modified kind. There, too, the idea is that an initial agreement, struck under special conditions of fairness, settles the principles of justice that will govern a society. The fundamental thought driving social contract theories is undeniably intuitive: What else could justify social rules and principles but the agreement of those who are to live under them? But, of course, there are fairly obvious problems with the very idea of a hypothetical prosocial fair agreement that results in principles and rules to govern actual societies. In Social Contract Theory for a Diverse World: Beyond Tolerance (Routledge, 2017), Ryan Muldoon (SUNY Buffalo) launches an original kind of criticism of social contract theory, both in its classical and current formulations. According to Muldoon, extant social contract theories do not take sufficient account of diversity. Muldoon then proposes a revised version of social contract theory, and also a reorientation in political philosophy itself. In Muldoon’s hands, social contract theory is not aimed primarily at the production and justification of principles of justice; rather, the social contract is a tool of discovery in an ongoing social experiment.