Democritus, c.460-c.370 BC, a Greek philosopher, developed and systematized classical atomism, a theory credited to his teacher Leucippus. The theory postulated a world made up of hard, indivisible (hence atomic, from Greek atoma, "uncuttable") particles of matter moving through empty space.


According to Democritus, the atoms had shape, mass, and motion but no other qualities, such as color or flavor. These latter were supplied by the observer and were subjective. Democritus described them as existing by convention or by custom (nomos), as opposed to existing by nature (physis). The atoms had various shapes, Democritus thought, for "why should they have one shape rather than another?" All change was to be explained by reference to the transfer of momentum as the atoms collided. Democritus suggested that our cosmos was formed by a spinning vortex of such atoms and that there were an infinite number of worlds formed in the same way.


Democritus' belief in the unchanging nature of the intelligible universe and the changing nature of the sensible universe was a direct confrontation of the ideas of Parmenides, who denied all change, and Heraclitus, who denied all constancy. His ethics were also a path between the extremes of these two philosophers. Democritus' ethical naturalism rejected any teleology or belief in chance that would deny people's responsibility for their own well-being. He rejected all supernatural sanctions of human behavior, thought that belief in an afterlife was a ridiculous fiction, and held that it was an individual's conscience alone that determined right or wrong action. Because of this, perhaps, Democritus was known in ancient and medieval art and letters as the "laughing philosopher," in contrast to Heraclitus, the "weeping philosopher."


Robert S. Brumbaugh


Bibliography: Furley, David, The Greek Cosmologists (1987); Guthrie, W. K. C., A History of Greek Philosophy, 2 vols. (1962; repr. 1979).

Last modified on: Friday, October 17, 1997.