Leucippus & Democritus (Atomists) c 430 bc

Russell argues that it is difficult to separate Leucippus and Democritus because they were generally mentioned together and cross-attributed. Leucippus was earlier, with Democritus in fact a contemporary of Socrates and the Sophists (Russell discusses him earlier because of his link with Leucippus).

They were atomists; they believed that everything was composed of atoms, which were physically, but not geometrically, indivisible. They thought that there was empty space between the atoms and that they were indestructible, always in motion and infinite in number.

Many of there contemporaries apparently criticised them for attributing everything to chance but Russell argues that they were in fact determinists. Russell argues that, in contrast to Socrates, Plato and Aristotle, they sought to explain the world without the notion of purpose or final cause, asking the more mechanistic (and scientific) 'what caused this?' rather than 'what purpose did this serve?'. They attempted to reconcile the ideas of Parmenides with the observable reality of motion and change.

Democritus was a materialst; he thought the soul was composed of atoms and that thought was a physical process. He disbelieved in popular religion. He approved of cheerfulness, moderation, friendship and democracy and disliked sex, violence and women.

Russell argues that Greek philosophy decayed in some senses after Democritus, moving away from a scientific, imaginative discovery of the world to the scepticism of the Sophists and a focus on the study of how we know rather than on acquiring new knowledge, Socrates' emphasis on ethics, Plato's rejection of the world of the senses in favour of pure thought and Aristotle's belief in purpose. Although Aristotle and Plato were geniuses, Russell feels that they sowed the seeds of the later decay of philosophy.