Noun
English Wikipedia has an article on:modus tollensWikipedia
modus tollens (uncountable)
(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.
In instances of modus tollens we assume as premises that p → q is true and q is false. Source: Internet
The modus tollens rule can be stated formally as: : where stands for the statement "P implies Q". Source: Internet