Note 16 — Chapter V · ANALYTICA PRIORA I.
Reading edition
We find Aristotle declaring in Topica, II. viii. p. 113, b. 15, that in converting a true Universal Affirmative proposition, the negative of the Subject of the convertend is always true of the negative of the Predicate of the convertend; e.g. If every man is an animal, every thing which is not an animal is not a man. This is to be assumed (he says) upon the evidence of Induction — uncontradicted iteration of particular cases, extended to all cases universally — λαμβάνειν δ’ ἐξ ἐπαγωγῆς, οἷον εἰ ὁ ἄνθρωπος ζῷον, τὸ μὴ ζῷον οὐκ ἄνθρωπος· ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων.… ἐπὶ πάντων οὖν τὸ τοιοῦτον ἀξιωτέον.
The rule for the simple conversion of the Universal Negative rests upon the same evidence of Induction, never contradicted.