Vagueness as Semantic

I shall argue that vagueness, understood as a semantic phenomenon, can be accommodated within standard semantics by assimilating it to contingency in standard modal semantics and suitably modifying the pragmatics. I claim that vagueness in natural language is not a defect and that accommodating it is therefore obligatory for semantic frameworks for natural languages. In section 17.2, I interpret the claim that vagueness is a semantic phenomenon as involving at least the claim that vague predicates do not determine an extension. I then outline three ways in which standard semantics can account for the failure of an expression to determine an extension, namely ambiguity, indexicality and relativity to circumstances of evaluation (e.g. contingency). I point out some problems with treating vagueness as a form of ambiguity or as a form of indexicality. Then I explain the view that vagueness is a form of relativity to circumstances of evaluation, and why such a view needs to provide an account of the normative significance of truth for assertion and belief. I show how this normative role is constrained by the two desiderata that we explain the seductiveness of sorites arguments and give an account of borderline cases. Finally I briefly consider higher-order vagueness and conclude by comparing the account given with other views of vagueness.