FIGURES OF PROSLEPTIC SYLLOGISMS IN PRIOR ANALYTICS 2.7

Abstract

In chapters 2.5–7 of the Prior Analytics Aristotle is concerned with what he calls circular proof. He gives an account of circular proofs within the framework of his syllogistic theory, and discusses how they come about in the three figures of categorical syllogisms. The results of this discussion are summarized at the end of chapter 2.7, at 59a32–41. The summary contains several statements to the effect that certain circular proofs come about in the third figure. Some of these statements are problematic because the circular proofs in question are actually not in the third figure of categorical syllogisms; in fact, these circular proofs are not categorical syllogisms at all, but what Theophrastus called prosleptic syllogisms. Hence, the statements are incorrect if they are understood to refer to the third figure of Aristotle’s categorical syllogisms. Since it seems natural to understand them in this way, Ross and others conclude that the passage at 59a32–41 is spurious and should be excised, although it is found in all MSS. 1 By contrast, this paper aims to show that the passage is not spurious. Following Pacius, I argue that the problematic statements in it refer not to the third figure of categorical syllogisms, but to the third figure of prosleptic syllogisms. On this interpretation, the statements are correct and can be regarded as genuine. Given that they are genuine, they show that Aristotle was aware of a classification of prosleptic syllogisms into three figures, even though such a classification does not occur elsewhere in his writings. Thus, the passage at 59a32–41 appears to be the earliest evidence we have of figures of prosleptic syllogisms. I begin with an overview of Aristotle’s treatment of circular proofs in Prior Analytics 2.5–7, focussing on his use of prosleptic syllogisms (§1). Readers familiar with the contents of Prior Analytics 2.5–7 may wish to skip this overview. Next we consider the problematic statements in 59a32–41 (§2). I will argue that these statements refer to the third figure of prosleptic syllogisms, and that there is no reason to doubt Aristotle’s authorship of the passage (§3).