modus tollens

British  

/ ˈməʊdəs ˈtɒlˌɛnz /

noun

1. 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

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Etymology

Origin of modus tollens

literally: mood that denies

Example Sentences

You can also use your knowledge of necessary and sufficient conditions to understand the last form, modus tollens.

From Textbooks • Jun. 15, 2022

Moore’s argument takes the form of what is known as modus tollens, meaning a valid inference where the consequence of a conditional is denied.

From Textbooks • Jun. 15, 2022

The modus tollens of reasoning from known inferences to the unknown proposition, is not only a rigorous, but a very easy mode of proof.

From The Critique of Pure Reason by Meiklejohn, John Miller Dow