Strategic Vagueness, and Appropriate Contexts

This paper brings together several approaches to vagueness, and ends by suggesting a new approach. The common thread in these approaches is the crucial role played by context. In Section 2, we treat game-theoretic rationales for vagueness, and for the related concepts of ambiguity and generality. Common about these rationales is that they are based on the assumption of a conflict of interest between speaker and listener. We review this literature using a single example. We argue that the most plausible application to vagueness in natural language of these models is one where the listener only imperfectly observes the context in which the speaker makes her utterances. Yet, it is clear that not all vagueness can be accounted for by conflicts of interest. This is why the rest of the paper looks at the case of common interest. Section 3 argues that being vague by saying that someone is bald makes sense in a context where precision is of less importance; in a context where precision is of more importance, one can then refer to someone as completely bald. This make sense because the longer and therefore more costly to utter expression ‘completely bald’ is then used less often. Vagueness is thus seen as an application of Horn’s pragmatic rule that (un)marked states get an (un)marked expression. Section 4 tackles the Sorites paradox, which apparently leads to the violation of standard axioms of rational behaviour, and shows that this paradox arises from the use of vague predicates in an inappropriate context. If, as suggested by the Sorites paradox, fine-grainedness is important, then a vague language should not be used. Once vague language is used in an appropriate context, standard axioms of rational behaviour are no longer violated. Section 5 finally takes a different approach from the previous sections, and following prospect theory assumes that context directly enter agents’ utility functions in the form of reference points, with respect to which agents think in gains and losses. The rationale for vagueness here is that vague predicates allow players to express their valuations, without necessarily uttering the context, so that the advantage of vague predicates is that they can be expressed across contexts.