A.contradiction of propositions, Arist.Int.17a33, AP0.72a12, Metaph.1011b23, 1055b1, al.; “ἐξ ἀντιφάσεως” per contra, Porph.Chr.58; ἐξ ἀντιφάσεως συλλογισμός, e.g. 'either there is day or there is not day', Chrysipp.Stoic.2.87; ἡ κατ᾽ ἀντίφασιν ἐρώτησις, e.g. 'Does A possess B or not?', Ps.-Alex. Aphr.in SE81.35, cf. 103.16.
II. contradictory proposition, Arist. Int.22a39, APr.34b29, al.