Logic / Unit 9 Logic 430 short lesson, about 20 seconds
Rebuttals vs. Undercutters
Captions available
The idea
A rebuttal argues the conclusion is false; an undercutter argues the support doesn't hold — leaving the conclusion open.
In practice
"The witness is lying" rebuts nothing about the defendant; it undercuts one line of support.
Where people slip
Confusing them overclaims: destroying an argument for p is not establishing not-p. That confusion has its own name.
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.
Something wrong in this lesson? Flag it · Sources for Logic