Underspecification and Communication

It has recently been argued that our use of vague language poses an intractable problem for any account of content and communication on which (i) the things we assert are propositions and (ii) understanding an assertion requires recognizing which proposition the speaker asserted. John MacFarlane has argued that this problem concerning vague language is itself a species of an even more general problem for such traditional accounts—the problem posed by “felicitous” underspecification. Repurposing certain ideas from Allan Gibbard, MacFarlane offers a novel theory of vagueness, plan-expressivism, as an account that can handle both vagueness and such underspecification in communication. In this paper, I argue that despite its many virtues, plan-expressivism fails as a general account of meaning and communication. In particular, I show that when it comes to the problem of felicitous underspecification, plan-expressivism fares no better than the more traditional accounts of content and communication it is intended to replace. Along the way, I argue that the problem of felicitous underspecification puts considerable pressure on an assumption that is at the core of both plan-expressivism and the accounts of its more traditionalist rivals – namely, that in cases of successful linguistic communication, we must always be able to find something – whether a propositional content or a conversational update – that the speaker is intending to share with her audience.