Philosophy / Unit 1 Philosophy 0019 short lesson, about 20 seconds
Validity
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The idea
A deductive argument is valid when it is impossible for all its premises to be true and its conclusion false.
In practice
"All fish fly. Trout are fish. So trout fly." Valid: the premises are false, but if they were true, the conclusion could not fail.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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