Sentence Examples with the word Modus tollens

Sigwart does not indeed shrink from this and greater absurdities; he reduces the first figure to the modus ponens and the second to the modus tollens of the hypothetical syllogism, and then, finding no place for the third figure, denies that it can infer necessity; whereas it really infers the necessary consequence of particular conclusions.

Two forms are possible (i.) modus ponens (which establishes the consequent set down in the major premise): if A is B, it is C (or C is D); A is B; therefore A is C (or C is D), and (ii.) modus tollens (which disproves the antecedent): if A is B, it is C (or C is D); A is not C (or C is not D); therefore it is not B (or A is not B).