Democritean Atomism

Abstract

An atomic structure of matter was proposed by Leucippus and Democritus in Ancient Greece in the fifth century BC as a response to an argument of Parmenides to the effect that change is impossible. For the ancient atomists permanent reality consists of portions of being (atoms) each characterised by an unchanging shape and size. Change involves the motion and rearrangement of atoms. In effect, ancient atoms were like idealised stones moving and colliding in the void and sometimes becoming entangled. As well as the physical, stone-like, atoms proposed as a response to Parmenides, some early Greek philosophers proposed individual magnitudes as components of continuous magnitudes as a response to Zeno's paradoxes. These 'atoms' were distinct from physical atoms and I doubt if Democritus included them in his atomic theory. The Ancient Greeks, including the atomists, defended their accounts of the ultimate structure of reality by extracting principles from common sense that could plausibly be construed as self-evident and drawing their consequences by logical reasoning. The connection between the early philosophical atomic theories and experience was tenuous.