The Duality of Moral Language: On Hybrid Theories in Metaethics

Faculty opponent: Professor Mark Schroeder (University of Southern California)

Abstract
Moral language displays a characteristic duality. On the one hand, moral claims seem to be similar to descriptive claims: To say that an act is right (or wrong) seems to be a matter of making an assertion, thus indicating that the speaker has a moral belief about which she can be correct or mistaken. On the other hand, moral claims seem to be different from descriptive claims: There is a sense in which, by claiming that an act is right (or wrong), a speaker indicates that she is inclined to perform (or not perform) the act, to want others to perform it (or not perform it), and to react with praise towards those who do it (or blame or resentment towards those who do not). Hybrid theories maintain that utterances of moral sentences have both a descriptive and a practical linguistic function.

In this thesis, I investigate how a hybrid theory can best accommodate the descriptive and the practical aspects of moral language. I evaluate and criticize the way that existing hybrid theories have proposed to explain the duality of moral language. The main arguments against these views are that they either: fail to accommodate the way that the practical or attitudinal import of moral claims vary across different contexts and linguistic environments; or that they fail to show how the practical or attitudinal import is reliably inferred by interlocutors in virtue of general communicative principles.

I develop and defend a new hybrid theory called ‘dynamic descriptivism’. This theory accommodates the duality of moral language by appeal to the way that moral utterances affect a dimension of communication which consists of the shared assumptions that interlocutors mutually assume to mutually accept. Moreover, I discuss a problem which has affected a wide range of theories of moral language – including existing hybrid theories – which is the problem of explaining what it is that interlocutors disagree about when they disagree about matters of morality. I argue that that dynamic descriptivism offers new resources for solving this problem.