Reductio ad absurdum

Informal fallacies → Other informal

Reductio ad absurdum is when you take the other person's idea and push it to a silly extreme to make it look bad. When the extreme really does follow from their view, that can be a good argument. But sometimes the "silly" step doesn't really follow—you're just caricaturing their position. The fallacy is to claim the reductio follows when it doesn't. The remedy is to check whether the extreme case really is implied by their principle.

Examples

  • If we let people marry who they love, we'll have to let people marry tables.

  • If we allow this exception, we'll have to allow every exception.

  • If you support welfare, you support everyone living on benefits.

  • If we regulate this, next we'll regulate everything.

  • If we respect their beliefs, we have to respect all beliefs including dangerous ones.

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