Moral claims not only assume to be true, but they also guide our choices. This fascinating book presents a new theory of normative judgment, the "standard-based theory," which offers a schematic account of the truth conditions of normative propositions of all kinds, including moral propositions and propositions about reasons. Here, David Copp argues that because any society needs a social moral code in order to enable its members to live together successfully, and because it would be rational for a society to choose such a system, certain moral codes—and the standards they include—are justified. In this work, Copp raises a number of important issues in moral theory, as well as in metaphysics and the philosophy of language.