Single Idea 9605

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

Full Idea

The law of excluded middle says if a proposition is false, then its negation is true

Gist of Idea

If a proposition is false, then its negation is true

Source

James Robert Brown (Philosophy of Mathematics [1999], Ch. 1)

Book Reference

Brown,James Robert: 'Philosophy of Mathematics' [Routledge 2002], p.5


A Reaction

Surely that is the best statement of the law? How do you write that down? ¬(P)→¬P? No, because it is a semantic claim, not a syntactic claim, so a truth table captures it. Semantic claims are bigger than syntactic claims.