Note 80 — Chapter VII · ANALYTICA POSTERIORA I.
Reading edition
Ibid. I. xxvi. p. 87, a. 2-30. Waitz (II. p. 370), says: “deductio (ad absurdum), quippe quæ per ambages cogat, post ponenda, est demonstrationi rectæ.”
Philoponus says (Schol. pp. 234-235, Brand.) that the Commentators all censured Aristotle for the manner in which he here laid out the Syllogism δι’ ἀδυνάτου. I do not, however, find any such censure in Themistius. Philoponus defends Aristotle from the censure.