Abstract
In this chapter, Hankinson discusses the theory of Atomism, from Leucippus and Democritus to Epicurus and his followers. The early Atomists were concerned with the circumvention of the Eleatic denial of motion; they did so by positing unchanging atoms and the existence of the void in which the atoms move. Democritean Atomism is thoroughly mechanistic and reductionist; Epicurean Atomism is ontologically more generous, accepting, for instance, the reality of properties and guaranteeing, by virtue of the controversial notion of the ‘swerve’, the exercise of free will. Thus, although strictly speaking it denies uncaused events, Epicureanism nevertheless holds that human action is not subject to determinism. The later Epicureans also reject the Stoic view that fundamental physical principles are logically necessary truths.