contraposition the immediate logical operation on any categorical proposition that is accomplished by first forming the complements of both the subject term and the predicate term of that proposition and then interchanging these complemented terms. Thus, contraposition applied to the categorical proposition ‘All cats are felines’ yields ‘All non-felines are non-cats’, where ‘nonfeline’ and ‘non-cat’ are, respectively, the complements (or complementary terms) of ‘feline’ and ‘cat’. The result of applying contraposition to a categorical proposition is said to be the contrapositive of that proposition. See also SQUARE OF OPPOSITION , SYLLOGIS. R.W.B.