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Democritus and atomism
c. 460–370 BC· Philosopher· Reality, mind & God
Mostly agreedGood evidence; some details uncertain.
A Greek from Abdera who, with his teacher Leucippus, held that everything consists of tiny indivisible atoms moving through empty space.
See it on the Philosophy map →The idea
Idea: reality is atoms (atomos, 'uncuttable') and void. Reasoning: Parmenides said change requires 'nothing' to exist; Democritus accepted that empty space exists, so atoms can move and recombine. Atoms never change, satisfying Parmenides, but their arrangements do, explaining change. Colors and tastes exist 'by convention'; only atoms and void are real. Main objection: Aristotle argued a void is impossible and atoms cannot explain purpose in nature.
Why it matters
Atomism was revived by Epicurus, rediscovered in the Renaissance, and shaped modern chemistry and physics, though modern atoms turned out divisible.
Legacy and sources
Of some 70 works listed by Diogenes Laertius, only about 300 fragments survive, mostly ethical sayings; his physics is known through Aristotle, Epicurus and Lucretius.
Still debated
His views are hard to separate from Leucippus', who may have originated atomism; Epicurus even claimed Leucippus never existed.
Connections (3)
▸Parmenides of Elea was answered by Democritus and atomismMostly agreed
The connection
Parmenides argued that change would require 'nothing' to exist, which is impossible. Leucippus and Democritus accepted his logic but denied the premise: empty space does exist. Atoms that never change, like Parmenides' Being but countless and tiny, move through the void, so change is only rearrangement.
When and how
Leucippus (perhaps from Miletus or Elea) and Democritus in Abdera, northern Greece, about 440–400 BC.
How sure are we?
Aristotle explicitly presents atomism as a reply to the Eleatics in On Generation and Corruption, Book 1, chapter 8.
Debates and open questions
How far atomism was a direct reply to Parmenides, rather than an independent physical theory that Aristotle later framed that way, is debated.
▸Democritus and atomism was adopted and revised by Epicurus and EpicureanismWell documented
The connection
Epicurus took over Democritus's picture of a world made only of atoms moving in empty space, but revised it: atoms have weight, come in limited sizes, and occasionally swerve. He also gave atomism a new job, ethics: once you see the world as atoms, fear of gods and death fades.
When and how
Late 4th century BC; Epicurus learned atomism from Nausiphanes, a follower of Democritus, on Teos, before founding his Garden in Athens around 307 BC.
How we know
Epicurus's Letter to Herodotus sets out his atomism; Cicero, Plutarch and others record both the borrowing and the changes, often accusing him of copying.
Debates and open questions
Epicurus claimed to be self-taught and disparaged Nausiphanes, so how much he owed Democritus directly, versus later atomists, is debated.
▸Democritus and atomism gave a materialist answer to What is ultimately real?Mostly agreed
The connection
Democritus answered that only atoms and void are real; everything else, from color to taste, is how atoms affect our senses. It was the first fully materialist answer: no gods, purposes or minds at the base of reality, only matter in motion.
When and how
Abdera, northern Greece, late 5th century BC.
How sure are we?
His fragment 'By convention sweet, by convention bitter... in reality atoms and void' is quoted by Sextus Empiricus.
Debates and open questions
Sources suggest he thought the soul was atoms too, yet his ethics seem to assume real choice; how he squared the two is still discussed.