Why were Stoic logicians especially interested in fallacies and refutations?

Stoic logicians were particularly interested in fallacies, paradoxes, and forms of refutation because their approach to logic was deeply rooted in the context of debate and public disputation. Unlike Aristotle, whose logical interests eventually shifted toward scientific demonstration, the Stoics maintained a primary focus on the practical challenges of argumentation.1

By studying these logical pitfalls, Stoic philosophers sought to refine their ability to navigate complex debates and defend their positions against opponents. This focus was consistent with their broader philosophical commitment to reason as the essential model for human existence and the primary tool for achieving a life in agreement with the world's rational design. Consequently, their development of propositional logic—which emphasized hypothetical propositions and inference schemata—was highly advanced, serving as a rigorous framework for analyzing the validity of arguments encountered in discourse.12