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Single Idea 9195

[from 'The Philosophy of Mathematics' by Michael Dummett, in 5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle ]

Full Idea

It must not be concluded from the rejection of excluded middle that intuitionistic logic operates with three values: true, false, and neither true nor false. It does not make use of true and false, but only with a construction being a proof.

Gist of Idea

Intuitionists reject excluded middle, not for a third value, but for possibility of proof

Source

Michael Dummett (The Philosophy of Mathematics [1998], 8.1)

Book Reference

'Philosophy 2: further through the subject', ed/tr. Grayling,A.C. [OUP 1998], p.178


A Reaction

This just sounds like verificationism to me, with all its problems. It seems to make speculative statements meaningless, which can't be right. Realism has lots of propositions which are assumed to be true or false, but also unknowable.

Related Idea

Idea 15941 For intuitionists excluded middle is an outdated historical convention [Brouwer]