contrapositive

[ kon-truh-poz-i-tiv ]

adjective

1. of or relating to contraposition.

noun

1. a contrapositive statement of a proposition.

contrapositive

/ ˌkɒntrəˈpɒzɪtɪv /

adjective

1. placed opposite or against

noun

1. logic
   1. a conditional statement derived from another by negating and interchanging antecedent and consequent
   2. a categorial proposition obtained from another, esp validly, by any of a number of operations including negation, transferring the terms, changing their quality, and also possibly weakening from universal to particular

Word History and Origins

Origin of contrapositive¹

First recorded in 1855–60; contraposit(ion) + -ive

Example Sentences

In the case of the I proposition the contrapositive is impossible, as infringing the main rule of conversion.

From Project Gutenberg

Every positive in thought has a contrapositive, and the positive and contrapositive are of the same kind.

From Project Gutenberg

But take the obverse of the contrapositive of both premises: All m is p; All m is s: ∴ Some s is p.

From Project Gutenberg

As before, the conclusion in the constructive type resolves itself into the subalternate of the major itself, and in the destructive type into the subalternate of its contrapositive.

From Project Gutenberg

Every impression felt is felt as a change or transition from something else: but it is a variation of the same impression—the something else, the contrapositive, is not entirely different.

From Project Gutenberg