noun
Technical term in logic; refers to the inference that derives a new proposition by switching the subject and predicate and negating both.
換質換位は伝統的論理学で用いられる推論形式の一つである。
Contraposition is one of the inference forms used in traditional logic.
対偶 is the more common modern term for contraposition in logic; 換質換位 is a traditional, less frequently used synonym.
Compound of 換質 (change of quality) and 換位 (change of position), reflecting the logical operations of negation and subject-predicate reversal.