Full Idea
'Modus ponendo tollens' (MPT) says that if the negation of a conjunction holds and also one of its conjuncts, then the negation of the other conjunct holds. Thus P, ¬(P ∧ Q) |- ¬Q may be introduced as a theorem.
Gist of Idea
'Modus ponendo tollens' (MPT) says P, ¬(P ∧ Q) |- ¬Q
Source
E.J. Lemmon (Beginning Logic [1965], 2.2)
Book Reference
Lemmon,E.J.: 'Beginning Logic' [Nelson 1979], p.61
A Reaction
Unlike Modus Ponens and Modus Tollens, this is a derived rule.