Oppenheim's Defense of Noncognitivism

In his recent book, Moral Principles in Political Philosophy, Felix Oppenheim provides a useful examination of the assumptions of well known figures in the history of political philosophy concerning the logical status of moral principles. Classifying them as cognitivists (if they view fundamental moral principles as either true or false) or noncognitivists (if they view moral principles as neither true nor false), Oppenheim attempts to exhibit the inadequacy of the cognitivist point of view and, importantly, the adequacy of the noncognitivist position. My critique aims at demonstrating the inconclusiveness of Oppenheim’s arguments against cognitivism. Oppenheim presupposes the availability of a plausible and workable criterion for determining when a sentence counts as a statement (statements are for Oppenheim entities which are true or false and, thus, “cognitively meaningful”), but he fails to provide any attractive candidate for that position. Further critical discussion revolves around the following related questions: Is there adequate positive support for the noncognitivist view? Does it allow for the rationality of fundamental moral commitments? And can Oppenheim really justify his case that, far from being irrational or pernicious, noncognitivism is naturally associated with certain humanistic ideals, such as toleration of those of differing moral and political viewpoint?