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affirming the consequent

The invalid form: if P, then Q; Q; so P.

Affirming the consequent is the formal fallacy: if P, then Q; Q; therefore P. It imitates modus ponens but asserts the consequent instead of the antecedent. Q may be true for some other reason.

Examples

  • "If it's a cat, it has fur. My pet has fur. So it's a cat." It could be a dog.

See also

modus ponens denying the antecedent formal fallacy
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