“Nothing happens at random, but everything from a rational principle and of necessity.” – Leucippus.1
Continuing now with the views of ultimate reality of the pre-Socratic Greek philosophers, we leave behind the insights of the Milesians and move to the Atomists – Leucippus and Democritus. Little is known of Leucippus, not even his dates or birthplace, though he is thought to have lived in the fifth century B.C.E. His comprehensive account of the universe, Great World-System, is lost to history, but according to Aristotle he was the originator of atomism. Our knowledge of his theories survive mainly second hand and through fragments of his successor, Democritus (circa 460-370 B.C.E.), who wrote lost works on astronomy, other natural sciences, mathematics, epistemology, and ethics.2
Leucippus and Democritus can be seen as the earliest theoretical physicists who derived their theories from an uncanny deduction, rather than from scientific induction. In responding to Parmenides who denied the possibility of change and of non-being, the Atomists concluded, “Not-being exist as much as being.”3 Not-being for the atomists is space, also called the “void” or “nothing” or the “infinite,” while Being is atoms, also called the “compact.” Their argument is simple enough; if perceptible objects are continually divided into progressively smaller parts, there must be at last the smallest parts which can no longer be divided. This indivisible matter – a-tomon meaning “uncuttable”4 – is not perceptible and is continuously in motion. Differences in perceptible objects reflect differences in the shape, arrangement, and position of atoms of varying sizes. Logically, space or “what is not” is required for motion to be possible.
Some remarkable consequences of these simple deductions follow. First, matter and objects are generated by the joining of atoms and undone by the dissolution of the aggregates.5 Second, the motions of the atoms responsible for the material world are determined, that is the explanation of natural processes is mechanical, meaning physical laws, not intelligent design. Third, changes in the universe are quantitative rather than qualitative, that is, subject to mathematical reasoning. For example, Democritus is the first to realize that variation in weight may be due to differences in numbers of atoms.6 Fourth, color, sound, and taste are secondary qualities incident to the interaction of atoms with the sense organs;7 thus Democritus anticipates Kant’s theory that we cannot know the thing-in-itself. Last, again using only deduction, Democritus explains how the heavenly bodies come into existence: large groups of atoms become isolated in the void, conglomerate to form a whirl or vortex with finer atoms in the outer area and heavier ones in the center so that a spherical mass forms dragging still more atoms into it by the whirl.8
Therefore the atomists retain the general view of nature as a multitude of phenomena based on an underlying unity, seemingly building on much of the Milesians’ thought, and achieve the most “coherent and economical physical system” in the ancient world, and the one most like our modern view. We turn next time to less scientific models that attempt to address the more abstract or obscure nature of reality and its paradoxes.
1 Honderich, Ted, The Oxford Guide to Philosophy. Oxford University Press, 2005. ISBN 978-0-19-534093-8, page 512.
2Ibid., page 198.
3Allen, Reginald E., Greek Philosophy: Thales to Aristotle. The Free Press, New York, NY, 1966. Page 16.
4Honderich, Ted (editor), The Oxford Guide to Philosophy. Oxford University Press, 2005. ISBN 978-0-19-534093-8, page 198.
6Edwards, Paul (editor), The Encyclopedia of Philosophy. Macmillan Publishing Co., Inc. & The Free Press, 1972. Volume 1, page 194.
7Allen, Reginald E., Greek Philosophy: Thales to Aristotle. The Free Press, New York, NY, 1966. Page 16
8Edwards, Paul (editor), The Encyclopedia of Philosophy. Macmillan Publishing Co., Inc. & The Free Press, 1972. Volume 4, page 448.