c. 490-c. 430 B.C.

Greek Philosopher

The accomplishments of the Eleatic philosopher Zeno illustrate the law of unintended effect. Setting out to justify the propositions put forth by his teacher Parmenides, namely that change is impossible, Zeno achieved something quite different. Intentionally or not, his famous paradoxes showed both the power and the limitations of logic, and philosophers' interest in the challenges posed by these problems led to the formalization of logic, or dialectic, as a discipline.

Like Parmenides (b. c. 515 B.C.), Zeno came from Elea, a Greek colony in southern Italy. At about the age of 40, in 449 B.C., he accompanied his teacher to Athens, where he met and impressed Socrates (c. 470-390 B.C.) In fact, much of what is known about Zeno's career comes from the writings of Socrates's own pupil, Plato (427-347 B.C.).

Parmenides taught that nonbeing is...