Proving too much

Informal fallacies → Other informal

Proving too much is when your argument or principle, if taken seriously, would also "prove" something clearly false or absurd. So the argument is too strong for its own good and shouldn't be accepted. We can reject the principle or narrow it. The fallacy is to use a principle that has unacceptable implications. The remedy is to test the principle with other cases: if it would prove too much, we need to qualify or reject it.

Examples

  • We should never trust anyone who was ever wrong. So we can't trust any scientist, because every scientist has been wrong about something.

  • All killing is wrong. So killing in self-defence is wrong.

  • We should never take risks. So we shouldn't cross the road.

  • Any mistake disqualifies you. So one typo means we reject the whole application.

  • If we allow one exception, we must allow all.

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