Logic as Tool
Logic and rational argument are tools for reaching truth and living virtuously, not ends in themselves.
Stoics were masters of formal logic — Chrysippus developed propositional logic that remained unmatched until the 19th century. Yet they insisted logic is a tool in service of ethics and physics. Cleverness in argument without wisdom in living is merely sophistry.
Logic's task is to guard truth from error.
Stoic logic influenced medieval scholastic logic and contributes to the history of formal logic that culminates in modern mathematical logic.
Lives of Eminent Philosophers