Despite an impressive philosophical pedigree, contractualism (or contractarianism) has only been properly developed in two ways: by appeal to the idea of an instrumentally rational bargain or contract between self-interested individuals (Hobbesian contractualism) and by appeal to the idea of a substantively reasonable agreement among individuals who regard one another as free and equal persons warranting equal moral respect (Kantian contractualism). Both of these existing models of contractualism are susceptible to apparently devastating objections. In this article, I outline a third, 'deliberative' model of contractualism, which is based on the idea of a deliberatively rational agreement and which, I argue, represents a significant improve...