Full Idea
In a formal semantics we can label two properties 't' and 'f' and suppose that some sentences have neither (or both). Such a manoeuvre shows nothing of philosophical interest. No connection has been made between 't' and 'f' and truth and falsity.
Gist of Idea
The 't' and 'f' of formal semantics has no philosophical interest, and may not refer to true and false
Source
Timothy Williamson (Vagueness [1994], 7.2)
Book Reference
Williamson,Timothy: 'Vagueness' [Routledge 1996], p.190
A Reaction
This is right, and means there is a huge gulf between 'formal' semantics (which could be implemented on a computer), and seriously interesting semantics about how language refers to and describes the world.