The Beginnings of Formal Logic: Deduction in Aristotle’s Topics vs. Prior Analytics

Abstract

It is widely agreed that Aristotle’s Prior Analytics , but not the Topics , marks the beginning of formal logic. There is less agreement as to why this is so. What are the distinctive features in virtue of which Aristotle’s discussion of deductions ( syllogismoi ) qualifies as formal logic in the one treatise but not in the other? To answer this question, I argue that in the Prior Analytics —unlike in the Topics —Aristotle is concerned to make fully explicit all the premisses that are necessary to derive the conclusion in a given deduction.