Euclid of Megara, a Greek Socratic philosopher who lived around 400 BC, was the follower of Socrates. He is mainly known for founding the megarian philosophical school , and being confused with the famous mathematician Euclid of Alexandria by editors and translators of Euclid's Elements in the Middle Ages.

He was born in Megara, but in Athen he became the follower of Socrates. After Socrates's trial and death, Euclid went back to Megara, where, at his home, other frightened pupils of Socrates found an asylum. Euclid became the founder of megarian philosophycal school. As he said, The Good is One, but we can call it by several names, sometimes as wisdom, sometimes as God, sometimes as Reason, and he declared the opposite of Good does not exists. We don't know anything written by him.

His philosophy was a synthesis of the eleatic and socratic ideas. He identified the eleatic idea of One by the socratic idea of Good, but he called it Reason, God, and Mind too), and he said these were eternal and unchangeable. Because of these doctrines may contradict to empirical reality, they applied logic and rational reasoning to confute this. They descendants, the stoic logicians, were the deputizers of the most important logician school in the antiquity, beside peripatetics.

Euclid of Megara had three important pupils: Eubulides, Ichtyas – the second leader of the megarian school – and Thrasumakhus of Corinth, who was the master of Stilpo, who was the master of Zenon of Cythium; who was the founder of stoic school.

Resources

• Mates, Benson: Stoic Logic.