modus tollendo tollens

Etymology
Borrowed from   (roughly, “mode where infirming infirms”).

Noun

 * 1)  A valid form of argument in which the antecedent of a conditional proposition is infirmed, thereby entailing the infirmation of the consequent. Modus tollendo tollens has the form:
 * 1. If non-P, then non-Q.
 * 2. non-P.
 * 3. Therefore, non-Q.

Hypernyms

 * See also Thesaurus:argument form
 * See also Thesaurus:argument form