modus tollens

• MT (initialism)

From Latin modus tollendō tollēns (“the mode where the denying denies”), from modus (“mode”) and forms of tollō (“I deny”).

modus tollens (uncountable)

1. (philosophy, logic) A valid form of argument in which the consequent of a conditional proposition is denied, thus implying the denial of the antecedent. Modus tollens has this form:

   1. If P, then Q.

   2. Not Q.

   3. Therefore, not P.

• inference rule
• See also Thesaurus:argument form

• modus ponens