On Aristotle’s Posterior Analytics A 13

I offer a novel divisio textus and overall interpretation of the first part of Posterior Analytics A 13. I argue that in this chapter Aristotle distinguishes why-syllogisms, which are from the primary cause, from that-syllogisms, which are not from the primary cause. Since a primary cause is convertible with the effect, a syllogism is a that-syllogism either because its middle term is a convertible effect of the major, or because it is a non-convertible cause of the major, or because it is a non-convertible effect of the major. These three ways the middle term may appear in a that-syllogism are introduced in the first part of APo A 13 according to the extensional relations between cause and effect.