Signs and demonstration in Aristotle

Abstract

ABSTRACTIn this paper, I explore the contrast drawn by Aristotle in two parallel passages of the Posterior Analytics (I.6, 75a28–37 and II.17, 99a1–4) between ‘signs’ and ‘demonstration’. I argue that while at APo. I.6 Aristotle contrasts demonstration proper with a deductively valid sign-syllogism (the tekmērion of APr. II.27), at APo. II.17 the contrast is rather between a demonstration proper and a deductively invalid sign-syllogism (the sēmeion in the strict sense of APr. II.27).