High Quality Content by WIKIPEDIA articles! In traditional logic, contraposition is a form of immediate inference in which from a given proposition another is inferred having for its subject the contradictory of the original predicate, and in some cases involving a change of quality (affirmation or negation). For its symbolic expression in modern logic see the rule of transposition. Contraposition also has distinctive applications in its philosophical application distinct from the other traditional inference processes of conversion (logic) and obversion where equivocation varies with different proposition types.