It would be easy to diverge from this general overview into a detailed examination of the physics. This is because Epicurus seems to have been largely right. We now believe, as he did, that the universe is made of atoms, and if we do not now talk about motion, we do talk about energy and force. His physics are an astonishing achievement.
Of course, he was often wrong. He denigrated mathematics. He seems to have believed that the sun and moon were about the same size as they appear to us. Then there is an apparent defect in his conception of the atomic movements. Does the universe exist by accident? Or are their laws of nature beyond the existence and movement of the atoms? The first is not impossible. An infinite number of atoms in an infinite void over infinite time will, every so often, come together in an apparently stable universe. They may also hold together, moving in clusters in ways that suggest regularity. But this chance combination might be dissolved at any moment — though, given every sort of infinity, some of these universes will continue for long periods.
If Epicurus had this first in view, what point in trying to explain present phenomena in terms of cause and effect? Causality only makes sense on the assumption that the future will be like the past. If he had the second in mind, it is worth asking what he thought to he nature of these laws? Might they not, for example, have had an Author? Since Newton, we have contented ourselves with trying to uncover regularities of motion and not going beyond these. But the Greeks had a much stronger teleological sense.
Perhaps these matters were not discussed. Perhaps they were discussed, but we have no record of them in the surviving discussions. Or perhaps they have survived, but I have overlooked them. But it does seem to me that Epicurean physics do not fully discuss the nature of the laws that they assume.
On the other hand, let me quote two passages from his surviving writings:
Moreover, there is an infinite number of worlds, some like this world, others unlike it. For the atoms being infinite in number… are borne ever further in their course. For the atoms out of which a world might arise, or by which a world might arise, or by which a world might be formed, have not all be expended on one world or a finite number of worlds, whether like or unlike this one. Hence there will be nothing to hinder and infinity of worlds….
And further, we must not suppose that the worlds have necessarily one and the same shape. For nobody can prove that in one sort of world there might not be contained, whereas in another sort of world there could not possibly be, the seeds out of which animals and plants arise and the rest of the things we see.
What we have here is the admission that there may, in the infinite universe, be other worlds like our own, and these may contain sentient beings like ourselves. And there may be worlds inconceivably unlike our own. And there is the claim that living beings arise and develop according to natural laws. Epicurus would not have been surprised either by modern physics or by Darwinism. […]
However, while the similarities between Epicurean physics and modern science are striking, there is one profound difference. For us, the purpose of science is to give us an understanding of the world that brings with it the ability to control the world and remake it for our own convenience. This is our desire, and this has been our achievement because we have fully developed methods of observation and experiment. The Greeks had limited means of observation — no microscopes or telescopes, nor even accurate clocks. Nor had they much conception of experiment.
Moreover, scientific progress was neither conceived by Epicurus nor regarded as desirable. He says very emphatically:
If we had never been troubled by celestial and atmospheric phenomena, nor by fears about death, nor by our ignorance of the limits of pains and desires, we should have had no need of natural science.
He says again:
…[R]emember that, like everything else, knowledge of celestial phenomena, whether taken along with other things or in isolation, has no other end in view than peace of mind and firm convictions.
Sean Gabb, “Epicurus: Father of the Englightenment”, speaking to the 6/20 Club in London, 2007-09-06.
October 16, 2016
QotD: Epicurean physics
September 7, 2016
QotD: Plato, Epicurus and Democritus
For Plato, the world of appearance was a kind of dream, and the real world was something that only the initiated could begin to understand through logic and mathematics, and perhaps a dash of magic. So far as it existed, matter was evil, and the universe was strictly bounded in space and time.
For Epicurus, the world of appearance was the real world. There is a void, or vacuum, which is infinite in space and time. It has always existed. It will always exist. It goes on forever and ever. In this void is an infinite number of atoms. These are very small, and therefore imperceptible, but indivisible particles of matter. They have always existed and will always exist. They are all moving through the void at an incredibly rapid and uniform speed. The world as we see it is based on combinations of these atoms. Every atom is hooked, and the collision of atoms will sometimes lead to combinations of atoms into larger structures, some of which endure and some of which we can eventually perceive with our senses. All observed changes in the world are the result of redistributions of the invisible atoms that comprise it.
Though we are not able to see these atoms, we can infer their existence by looking at the world that our senses can perceive. All events — the wearing away of a rock by water, for example, or the growth of crystals or trees — can be fully explained by an atomic hypothesis. Since there is nothing that cannot be so explained, there is no need of any other hypotheses. In a surviving explanation of his method, he says:
…[I]n our study of nature we must not conform to empty assumptions and arbitrary laws, but follow the prompting of the facts.
Everything in the universe is made of atoms. We are made of atoms. Our souls are made of very fine atoms. Our senses work because every other physical object is continually casting off very thin films of atoms that represent it exactly as it is. These films strike on our senses and give us vision and sound. Heat is produced by the vibration of atoms temporarily trapped in structures that prevent them from their natural onward motion.
Whether or not anyone can at any moment think of a likely explanation, all events in the universe can be explained in purely naturalistic terms. Assuming atoms and motion, no further hypotheses are needed to explain the world.
Epicurus was not the first to explain the world by an atomic hypothesis. That was Democritus (460-370 BC). But he seems to have developed the hypothesis with a consistency and detail that took it far beyond anything that earlier philosophers had conceived.
Perhaps his most notable innovation is the doctrine of the swerve. There are two objections to the atomism of Democritus. The first is that if the atoms are all moving at the same speed and in the same direction, like drops of rain, there is no reason to suppose they will ever collide and form larger compounds. The second is that if they are not moving in the same direction, they will collide, but they will form a universe locked into an unbreakable sequence of cause and effect. This conflicts with the observed fact of free will.
And so Epicurus argues that every atom is capable of a very small and random deviation from its straight motion. This is enough to give an indeterminacy to the universe that does not conflict with an overall regularity of action.
Sean Gabb, “Epicurus: Father of the Englightenment”, speaking to the 6/20 Club in London, 2007-09-06.
