Diogenes of Babylon

Diogenes of Babylon was a Stoic philosopher who led the Stoic school in Athens in the second century BC. He is also known as Diogenes of Seleucia, after the city in Babylonia where he was probably born. He belongs to the generation that followed Zeno of Tarsus and helped carry Stoicism forward at a time when Greek philosophy was opening itself to Academic and Peripatetic influences, which shaped his thought.

Born in Seleucia on the Tigris, he was educated in Athens under Chrysippus of Soli and, after Zeno of Tarsus, became head of the Stoic school there. His pupils included Panaetius of Rhodes and Antipater of Tarsus, who later succeeded him as scholarch. Sources suggest that he closely followed Chrysippus, especially on dialectic, and that he taught Carneades in this field. Around 155 BC he joined Carneades and Critolaus on an embassy to Rome to appeal a heavy fine imposed on Athens after the sack of Oropus. They spoke first in private gatherings and then before the Senate, and Diogenes won admiration for his sober and temperate style.

Almost none of his writings survive; we know them through quotations in later authors and through a number of titles, among them works on dialectic, on the ruling faculty of the soul, and on speech. In language and logic he made lasting contributions. He distinguished three levels of speech: sound, expression and word. Together with Chrysippus, he helped establish the classification of parts of speech. In ethics he examined how one should rationally choose among things that are indifferent. He is also associated with a move toward eclecticism, admitting elements from the Academy and the Peripatetics, and with a stronger emphasis on Stoic materialism. The Epicurean Philodemus cites him often in his writings on music, where Diogenes is said to have held that music can calm the passions, order the soul and encourage virtue.

His main legacy lies in passing Stoic doctrine to Panaetius, and through him to the Roman world.