Single Idea 17924

[catalogued under 5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle]

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


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]