Modus Tollendo Tollens

Proof Rule
The modus tollendo tollens is a valid deduction sequent in propositional logic.

Also see
The following are related argument forms:
 * Modus Ponendo Ponens
 * Modus Ponendo Tollens
 * Modus Tollendo Ponens

The Rule of Transposition is conceptually similar, and can be derived from the MTT by a simple application of the Rule of Implication.

These are classic fallacies:


 * Affirming the Consequent
 * Denying the Antecedent