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denying the antecedent

The invalid form: if P, then Q; not P; so not Q.

Denying the antecedent is the formal fallacy: if P, then Q; not P; therefore not Q. It imitates modus tollens but denies the antecedent instead of the consequent. Q may be true anyway.

Examples

  • "If you're a surgeon, you went to medical school. You're not a surgeon. So you didn't go to medical school."

See also

modus tollens affirming the consequent formal fallacy
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