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)
Book Reference
Williamson,Timothy: 'Vagueness' [Routledge 1996], p.187
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).
Related Idea
Idea 9133 Propositions are what settle problems of ambiguity in sentences [Sorensen]