Single Idea 12376

[catalogued under 5. Theory of Logic / A. Overview of Logic / 6. Classical Logic]

Full Idea

Demonstrations by reduction to the impossible assume that everything is asserted or denied.

Gist of Idea

Demonstrations by reductio assume excluded middle

Source

Aristotle (Posterior Analytics [c.327 BCE], 77a23)

Book Reference

Aristotle: 'Posterior Analytics (2nd ed)', ed/tr. Barnes,Jonathan [OUP 1993], p.17

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A Reaction

This sounds like the lynchpin of classical logic.