-340 – -284
Diodorus Cronus (fl. c. 300 BCE) was a Greek philosopher of the Megarian-Dialectical school, renowned for his contributions to propositional logic and modal theory. He is best known for the 'Master Argument' (Kyrieuon logos), which attempted to demonstrate that only what is or will be the case is genuinely possible. His strict definition of possibility and his analyses of conditional statements were highly influential on Hellenistic logic.
Formulated the Master Argument (Kyrieuon logos) linking the past's necessity to a strict definition of possibility
Defined possibility as 'what is or will be the case', rejecting unactualized possibilities
Developed an account of the 'connexive' or truth-functional conditional (the Philonian conditional)
Advanced propositional logic independently of Aristotelian syllogistic
Influenced Stoic logic, particularly through his students Philo and Zeno of Citium