Making Sense of the Moral ‘Must’

I offer a critique of the dominant representationalist understanding of the moral ‘must’ and argue for an alternative understanding that is second-personal and performative. The representationalist understanding faces serious theoretical difficulties, having to do with the nature of the necessity that is supposedly referred to by the moral ‘must’; and it is also morally problematic, in that it encourages us to suppose that utterances of the form ‘N (morally) must φ’ may be understood, and their truth assessed, altogether apart from such morally significant matters as the nature and history of the relationship between the speaker and her addressee(s) or the illocutionary force of the utterance. The alternative understanding dissolves the theoretical difficulties faced by those who have tried to vindicate a representational understanding of the moral ‘must’. It is also morally superior, in that it underscores the dependence of the sense of sentences of the form ‘N must φ’ – as uttered in moral contexts, and first and foremost in the second person – on morally significant contextual features such as who addresses whom, and with what illocutionary force, and what puts the first person in a position to address the other with these words and in that way.