- Lived:
- c. 214–129 BCE · born in Cyrene (North Africa); taught in Athens
- Tradition:
- Academic Skepticism — Plato's Academy in its skeptical phase, at its brilliant peak
- The Big Idea:
- Absolute certainty is impossible — but we don't need it. Beliefs can be graded: some are more credible, better tested, more trustworthy than others, and that is enough to think and act well.
- In their words:
- "If Chrysippus had not been, I would not have been."
- If you remember one thing:
- He wrote nothing, argued both sides of everything, and invented the idea that runs modern science and modern courtrooms alike: you can act rationally on evidence without ever claiming to be certain.