Logic / Unit 4 Logic 155 short lesson, about 20 seconds
Affirming a Disjunct
Captions available
The idea
p or q; p; therefore not-q. Invalid.
In practice
He's a veteran or a teacher. He's a veteran. "So he's not a teacher" — inclusive or: he may be both.
Where people slip
DS's evil twin. It secretly upgrades ∨ to exclusive-or without paying for it.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
Unlocks
- Nothing yet depends on this.
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