A Beginner's History of Philosophy, Vol. 1: Ancient and Mediæval Philosophy

by Herbert Ernest Cushman

Their Differences—The Development of the Meaning of Idea. 1. But the forms or ideas are so vitally different in the doctrines of these two philosophers that they have nothing in common save the name. On the one hand, Democritus took the word “idea” just as he found it in popular speech. It is the shape of a visible thing, the geometrical form of physical objects. It gets no new content in his hands, but is merely the physical atom. With Plato, however, the word gets a new meaning. He fills the form or idea with an ethical content. The idea as a quantity becomes now a quality. The idea becomes an Idea. The forms of Plato are logical species and teleological causes,while the forms of Democritus are atom-complexes.[23] In both philosophersthey are the norms of reality. But while Democritus still keeps his forms as the realities of physical nature, Plato conceives his forms to be true realities of objective human nature.

2. This vital difference between the two philosophers may get some explanation from the difference in the philosophical inheritance of each. To be sure, they were contemporaries, both being born in the Anthropological Period and both doing their most mature work in the Systematic Period. Both, too, were acquainted with the philosophy of the preceding time. But the ethical teaching of Socrates dominated Plato, and through it he became the legitimate perfecter of the Greek enlightenment and the anthropological movement. But what was the influence of Socrates upon Democritus? It seems to have been nothing. Why is Plato absolutely silent about Democritus when he mentions other Greek philosophers? No one has yet been able to say. Democritus stands at Abdera isolated from the ethical movement at Athens. The only influence upon him from that movement came from Protagoras, who was a member of the school at Abdera. Democritus is the finisher of the Cosmological movement.

The Life of Democritus (460–370 B. C.). Democritus was twenty years younger than Protagoras, about ten years younger than Socrates, and a generation older than Plato. He was outlived by Plato; and Aristotle was a young man when Democritus died. He was therefore contemporary with the intellectual movementgoing on in Greece, with Athens as a centre. While he does not appear to have come under the influence of Socrates, he was well acquainted with the destructive epistemology of the Sophists. Abdera, where he lived, is in Thrace, and seems to have been outside the Anthropological movement at Athens. The school of Leucippus was at Abdera; and Democritus was instructed in the Sophistic doctrine directly from Protagoras, who was a member of the Atomistic school before going to Athens. The three Systematic philosophers were wide travelers, Democritus not less than Plato and Aristotle. He traveled extensively through Greece, Egypt, and the Orient. He then returned to Abdera and began his scientific activity. He remained five years in Egypt, and came to know the greater part of western Asia. He returned to Abdera about 420 B. C., and therefore did not begin his teaching before he was forty years old. The length of time that Democritus, Plato, and Aristotle took for their apprenticeship, and the advanced age before they began their mastership, is remarkable. Democritus was the greatest investigator of nature in antiquity, and Aristotle used much of Democritus’ work for his own scientific writings. The ancients admired the writings of Democritus, and the loss of them in the fourth century after Christ is one of the most lamentable that has happened to the literary documents of antiquity. His works were extraordinary in number, and upon every known subject.

Democritus was the real exponent of the Atomistic school. The founder, Leucippus, belonged to the Cosmological Period; Protagoras, the Sophist, belonged to the Anthropological Period, and had great influence in thedevelopment of the school at Abdera; but Democritus, in systematizing the doctrines of Leucippus and in accepting the perception theory of Protagoras, became its most notable representative. He was the great systematizer of the Cosmologists, and yet he differed from all the Cosmologists in embodying in his theory the results of the Sophistic movement.

The Comprehensiveness of the Aim of Democritus. The reconstruction of the philosophy of Democritus has always been difficult for the historian because, from the originally great mass of his writings, only fragments remain. The fragments show, however, many interesting things: that he covered the entire range of experience in his investigations; that he was quite as much interested in psychical as in physical problems; that his contribution to epistemology was even greater than to physics; and that he was interested in the atomic theory because he believed that it was a working hypothesis for the explanation of experience of every kind. This last characteristic shows the systematic nature of his work and his right to stand with Plato and Aristotle. Democritus fully realized that the task of science was to explain experiences through a conception of reality. So he constructed his conception of the atom in order that he might explain phenomena intelligibly. He saw that no conception strange to experience or against experience, like the Eleatic Being, would answer scientific demands. A rational conception of absolute reality will have value only as experience testifies to it and, on the other hand, as it explains experience. Democritus valued his theory of the atoms because it seemed to explain all phenomena. This construction of a single fundamental rational principle for all kinds of phenomenashows how much more of a systematic scientist he was than the Cosmologists.

The Enriched Physics of Democritus—Hylozoism becomes Materialism. There is so great enrichment in elaboration and generalization in the physical doctrine of Democritus over that of Leucippus that it amounts to a change in principle. In all probability Leucippus, like other Cosmologists, was a hylozoist, and did not differentiate matter and life. He is to be grouped with the Reconcilers, or even with the Eleatics, rather than with Democritus. Democritus was a materialist. The period of forty years between himself and Leucippus had been the rich period of the introduction of psychological investigation and of the discrimination of psychical from physical processes. Materialism or spiritualism is not possible in the historical development of the human mind until it passes through just such a period of differentiation as the Sophistic Enlightenment. Before such a period there is animism and hylozoism; after such a period there is materialism and spiritualism of various sorts. Matter must be discriminated from spirit before one of the terms can be reduced to the other. So the hylozoistic pluralism of Leucippus became in the hands of Democritus a realistic materialism, pluralistic as well.

The reduction of all phenomena by Democritus to a mechanics of atoms was theoretically an enrichment of physics, for it anticipated the underlying principle of modern physics. The apparent qualities of things and the qualitative changes of things are conceived by Democritus to be in truth only a quantitative relation of atoms. He set before himself the task of explaining in detail how this or that quality consists of atoms in mechanical motion. The mental life of man must beexplained in the same way. So too, wherever he could, he emphasized more sharply than his predecessors the mechanical necessity of the movement of atoms. Impact caused by contact of the atoms was the cause of every occurrence and change. No event is to be explained as the manifestation of some spirit, or referred to some spiritual agency. Mechanical cause is behind every event; mechanical cause is the unifying principle of the doctrine of Democritus; mechanical cause is the reason for the chasm between the philosophy of Plato, of Aristotle, and that of Democritus. It is the reason, too, why the theory of Democritus was obscured until modern times. All teleological conceptions and all hylozoistic and animistic ideas are expelled from the theory of Democritus, on the assumption that spatial form and motion are simpler and more comprehensible terms of explanation. Thus for the first time we have a conscious outspoken materialism, and for the first time the world is conceived to be a universal reign of mechanical law.

The physical theory of Democritus also yielded a rich scientific explanation of the historical evolution of the universe. The universe, according to Democritus,—following the teaching of Leucippus,—consists of two parts: the Plenum or self-moving, qualitatively similar atoms; and the Void or empty space, in which the atoms move. The Plenum, or the atoms, is Being; the Void is not-Being.The atoms differ only in form and size;[24] they are infinite in number and therefore are of an infinite number of forms and sizes; they are imperceptibly small. The perceptible qualities do not belongto them, but to their motions. Motion is an irreducible function of atoms, and each atom, lawless in itself, is in flight through space. An aggregation of atoms arises when the atoms meet in their cosmic flight. The shock causes a vortex which draws more atoms into itself. Like atoms are drawn together, and the heavy atoms press the fine fire-atoms to the periphery. Thus innumerable worlds are formed, for any place of the meeting of several atoms can be the beginning of a new world. Sometimes small worlds are drawn into the vortices of large worlds, and sometimes large worlds disintegrate in fatal collisions. The worlds are therefore endless and in endless succession. The whole swings in space like a ball; the rim of the whole consists of compact atoms; the centre is filled with air. To much further length than we can go here Democritus developed a theoretical description of cosmic evolution upon the principle of mechanical necessity—and the description is almost modern.

The Materialistic Psychology of Democritus. It is easy to understand an explanation of the physical universe as atoms in motion; for our modern scientific theories of nature are set in these terms, even if we have transformed the Democritan static atom into a dynamic entity. It is rather more interesting to follow such a materialist as Democritus in his extension of the materialistic principle over upon the realm of the mental life.

In the first place, Democritus conceives man to be part and parcel of the world of atoms. Man is composed of all kinds of atoms. His body consists of earth, water, and air atoms. His mind is made up of fire atoms, which differ from the others in being the finest,smoothest, and most mobile. On this account the fire atoms are the most perfect of all. Psychical activity is the motion of fire atoms. They are scattered throughout the universe, and wherever they are, there is life. They are in plants and animals as well as in man. There is a larger collection of them in man, and this shows his superiority over other living things. In man there is a fire atom between every two other atoms, and the whole is held together by breathing. The different forms of mental activity are simply different forms of atomic motion.