Atomism

Lore & Background

In the 5th century BC, Leucippus and his pupil Democritus proposed that all matter was composed of small indivisible particles called atoms. Nothing is known about Leucippus except that he was the teacher of Democritus, who wrote prolifically but none of his treatises survive complete. Democritus argued that matter cannot be divided infinitely, so it must be made of extremely tiny particles. He believed atoms are too small for human senses, infinitely many, infinitely varied, and have always existed, floating in a void and varying in form, order, and posture. He maintained that atoms and void are the only things that exist; all other things exist only by social convention. A similar idea was developed independently by Kanāda of the Vaiśeṣika school, who proposed indivisible particles (paramāṇu). Indian Buddhists such as Dharmakirti developed distinctive theories involving momentary atoms (kalapas) that flash in and out of existence. In the early 19th century, John Dalton gave the name 'atom' to the particles of chemical matter for which experimental evidence was found, though the connection to historical atomism is at best tenuous.

Reader's Guide

Atomism stands as a foundational reductive argument in Western and Eastern philosophy, proposing that everything is composed of atoms and void and that nothing they compose really exists—only atoms ricocheting mechanistically in empty space. Democritus famously stated that by convention sweet is sweet, bitter is bitter, hot is hot, cold is cold, color is color, but in reality there are only atoms and the void. This view contrasts with substance theory, where a prime material remains qualitatively invariant under division. Atomism influenced later scientific thought, particularly through John Dalton's chemical atomism, though the modern concept of elementary particles is only tenuously connected to philosophical atoms. The theory aimed to remove the distinction drawn by the Eleatic school between absolute reality and the world of change, and it provided a mechanistic explanation for sensory qualities and material transformation.

Did You Know?

• Leucippus is the earliest figure whose commitment to Greek atomism is well attested and is usually credited with inventing it.
• Democritus believed bitterness is caused by small, angular, jagged atoms passing across the tongue, while sweetness is caused by larger, smoother, rounded atoms.
• Indian Buddhists such as Dharmakirti developed theories of momentary atoms (kalapas) that flash in and out of existence.
• Plato described solids as composed of indivisible triangles, with different arrangements leading to the four simple bodies of fire, air, water, and earth.