Full Idea
The law of excluded middle (for every proposition P, either P or not-P) must be carefully distinguished from its semantic counterpart bivalence, that every proposition is either true or false.
Gist of Idea
Excluded middle says P or not-P; bivalence says P is either true or false
Source
Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3)
Book Reference
Colyvan,Mark: 'An Introduction to the Philosophy of Mathematics' [CUP 2012], p.7
A Reaction
So excluded middle makes no reference to the actual truth or falsity of P. It merely says P excludes not-P, and vice versa.
Related Ideas
Idea 9024 Excluded middle has three different definitions [Quine]
Idea 8709 The law of excluded middle is syntactic; it just says A or not-A, not whether they are true or false [Friend]
Idea 18919 There are no 'falsifying' facts, only an absence of truthmakers [Engelbretsen]