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Modus Tollens as a Proof Move

This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.

State

From p ⊃ q and ~q, derive ~p.

Show

1. A ⊃ B. 2. ~B. 3. ~A (1, 2, MT).

Watch for

The negation must match the consequent exactly. ~B and B are the pair; ~B and ~~B are not — yet.

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Unlocks

  • Nothing yet depends on this.