Full Idea
A philosopher might endorse bivalence for propositions, while treating vagueness as the failure of an utterance to express a unique proposition.
Gist of Idea
We can say propositions are bivalent, but vague utterances don't express a proposition
Source
Timothy Williamson (Vagueness [1994], 7.2)
A Reaction
This idea jumps at out me as an extremely promising approach to vagueness, because I am a fan of propositions (and have written a paper on them). The whole point of propositions is that they are not ambiguous (and probably not vague).
Book Reference
Williamson,Timothy: 'Vagueness' [Routledge 1996], p.187
Related Idea
Idea 9133 Propositions are what settle problems of ambiguity in sentences [Sorensen]