Full Idea
The notion of truth and falsity apply to suppositions as well as to assertions.
Gist of Idea
Truth and falsity apply to suppositions as well as to assertions
Source
Timothy Williamson (Vagueness [1994], 7.2)
Book Reference
Williamson,Timothy: 'Vagueness' [Routledge 1996], p.187
A Reaction
This may not be obvious to those who emphasise pragmatics and ordinary language, but it is self-evident to anyone who emphasises logic.