Logic / Unit 5 Logic 194 short lesson, about 20 seconds
Modus Tollens as a Proof Move
Captions available
The idea
From p ⊃ q and ~q, derive ~p.
In practice
1. A ⊃ B. 2. ~B. 3. ~A (1, 2, MT).
Where people slip
The negation must match the consequent exactly. ~B and B are the pair; ~B and ~~B are not — yet.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Unlocks
- Nothing yet depends on this.
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