Full Idea
The meta-logical law of excluded middle is the meta-linguistic principle that any statement 'A' in the object language is either truth or false; it is now known as the principle of 'bivalence'.
Gist of Idea
'Bivalence' is the meta-linguistic principle that 'A' in the object language is true or false
Source
Timothy Williamson (Vagueness [1994], 5.2)
Book Reference
Williamson,Timothy: 'Vagueness' [Routledge 1996], p.145
A Reaction
[He cites Henryk Mehlberg 1958] See also Idea 21605. Without this way of distinguishing bivalence from excluded middle, most discussions of them strikes me as shockingly lacking in clarity. Personally I would cut the normativity from this one.
Related Idea
Idea 21605 Excluded Middle is 'A or not A' in the object language [Williamson]