The view expressed in the nineteenth century about Stoic logic, namely that it either copies Aristotle’s syllogistic or develops it in a vacuous and pedantic way, was accepted unanimously both in the histories of ancient philosophy and in the works focusing on the history of logic. From the early decades of the twentieth century on, however, given the important advances in the field of formal logic, it has finally become obvious that the Stoic logical system differed essentially from the Aristotelian and should be studied on its own merits. Indeed, the first reactions to the negative appraisal of Stoic logic came mainly from logicians, who were interested in the development of ancient logic and noticed the similarities between Stoic and propositional logic. The articles and books on the Stoics’ contribution to logic published since then, have managed to reconstruct in detail the Stoic logical calculus and to show its significance in the history of ancient logic.

These tutorials are an introduction to Stoic logic. My aim is to present the context from which Stoic logic emerged, to give as clearly as possible its basic features, and to assess its importance by comparing it to the Aristotelian syllogistic. No knowledge of ancient Greek is assumed.

• Session 1: The background of Stoic logic.
• Session 2: The Stoic logical system.
• Session 3: Stoic vs. Aristotelian syllogistic.