# modus tollens

(redirected from*Proof by contrapositive*)

Related to Proof by contrapositive: Proof by contradiction, Proof by induction

## modus tollens

(ˈməʊdəs ˈtɒlˌɛnz)*n*

(Logic)

*logic*the principle that whenever a conditional statement and the negation of its consequent are given to be true, the negation of its antecedent may be validly inferred, as in*if it's Tuesday this must be Belgium*and*this isn't Belgium so it's not Tuesday*[literally: mood that denies]

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

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