. In this short historical sketch I am indebted to two excellent secondary sources both for data relative to the history of ideas and for quotations from the pre-Socratics: B. A. G. Fuller, A History of Philosophy,
3rd ed., revised by Sterling M. McMurrin (New York, Henry Holt & Co., 1955), and W. T. Jones, A History of Western Philosophy
(New York, Harcourt, Brace & Co., 1952).
. A later follower of Parmenides got him out of this logical predicament by postulating the real as nonspherical and infinite in extent.
. For all his insistence on logic Parmenides seems to be guilty of a breach of logic in his first and all-important premise that nothingness is nonexistent. It is certainly true that when we think of nothingness we think something, i.e., a concept called “nothing.” In other words, according to Parmenides, to think “nothing” is to think a contradiction, and since a contradiction represents an unreal situation, “nothing” must be unreal, or nonexistent. The semanticist today would point out that Parmenides is here confusing the meaning
of “nothing” with its referent
in nature. To think “nothing” is to think of a meaning with a definite positive content and does not involve a contradiction, because the meaning of the term is quite different from the natural state to which it refers. As we shall see, the assertion of the real
existence of nothingness in the form of empty space was one of the revolutionary departures from Parmenidean logic made by the atomists.
. The word “atom” itself in Greek means “indivisible,” “irreducible.”
. There are a number of good laymen’s accounts to be had—for example, Fritz Kahn, Design of the Universe
(New York, Crown Publishers, Inc., 1954), especially pp. 51–127. Also Lancelot Whyte, Essay on Atomism: From Democritus to
1960 (London, Thomas Nelson & Sons, 1961).
38; cf. Lucr. 1.146–73 (=L1).
39; cf. Lucr. 1.232–37: “Infinite time and a day long past must necessarily have consumed all that is of mortal frame; but if in that span of time long past there have existed bodies out of which this universe of things is made new and now consists, such things of a certainty are gifted with a deathless substance. Hence no thing can revert to nothingness.”
41. All that remains of the ancient atomic theory today are the terms “atoms” and “particles”; in all other respects Epicurus’ description is completely wrong. The atom is not solid, it is not irreducible or immutable, and it is decomposable. Even the conception of “corporeality,” or matter, is radically different today; see note 5 above. However, it is worth noting from a purely historical point of view that the indivisibility of the atom was firmly accepted in nineteenth- and early twentieth-century physics. By the 1930’s the atom was pictured as a relatively simple structure, something like a miniature solar system, in which electrons moved in orbits around a central nucleus composed of protons and neutrons. But this simplicity of structure has been radically changed by the advanced techniques and refined instruments that have been developed more recently. Today the atom could more accurately be pictured as a jungle of elementary particles, some forty of which have so far been discovered, and the expectation is that still more remain to be discovered.
39; cf. Lucr. 1.265–328.
39–40. The student should note that the existence of empty space is proved indirectly by an argument called the reductio ad absurdum
(which is also a great favorite of Lucretius) . This consists in assuming the truth of the opposite
of the proposition you wish to prove and then showing that this leads to an absurdity. Given a pair of contradictories (e.g., here, “space either exists or does not exist”), if one is shown to be absurd or false, the other is necessarily true. By assuming hypothetically that space is nonexistent, two absurdities follow: “Bodies would not have anywhere to exist, nor would they have a medium through which to move.” Since bodies obviously do have a place to exist
and do move, Epicurus has indirectly proved the desired proposition: “Space exists.”
In this connection it is noteworthy that Epicurus makes no mention of time, which conceivably might be a third basic entity in the system of the universe. See Herod. 72–73 for his (rather unsatisfactory) treatment of time, and note 20 to that letter.
42. Note the use of the reductio ad absurdum
(note 11, above).
45. As we see from Pyth.
88–90 the general assumption made by the Epicureans was that each of these infinite worlds is geocentric, with a sun, moon, and stars. This, even in the absence of adequate observational techniques, would seem to indicate an excessive and uncritical reliance on analogy. A wide variety of shapes is allowed. Some worlds are spherical, others oval, others triangular, etc. “All these possibilities exist, inasmuch as they are not contradicted by any phenomenon in our own world.” The atomic generation of any such world is described in some detail in Pyth.
. Epicurus, if pressed, might have evaded this difficulty by a technical rejoinder: The sensed motion of any compound is an accident
(i.e., nonessential characteristic) of a particular collection of atoms, just as color, shape, and size are properties
(i.e., essential characteristics) of all atomic aggregates (Herod.
68–71). “We should not deny existence to these clear and distinct phenomena on the ground that they do not have the nature of the whole object of which they are accidents or the nature of permanent properties. Nor, on the other hand, should we regard them as things in themselves, because this is unthinkable in the case of both accidents and permanent properties. On the contrary, we should think of them . . . as what perception itself shows their peculiar nature to be.” (Herod.
71) This quotation grants a kind of existence to accidents such as sensed motion, but it does not tell us explicitly whether this existence is as real as that of atoms and void. “Things in themselves” does not refer to atoms and void but to supposed metaphysical entities such as motion per se,
se, etc. Democritus, on the other hand, took the strict view: “In reality there are atoms and void. That is, the objects of sense are supposed to be real, and it is customary to regard them as such, but in truth they are not. Only the atoms and the void are real.” (Frag. o; from Charles M. Bakewell, Source Book in Ancient Philosophy;
New York, Scribner’s, 1907).
. For the complete context, see Lucr. 2.251–93 (=L3, part II).
. The good name of Democritus should be protected from these criticisms. He was a complete determinist in both physics and ethics, which is much to his credit today, although not in ancient times. Most ancient philosophers upheld moral freedom in one sense or another and attempted to make man a partial exception to the natural order of “necessity.” Today the doctrine of metaphysical free will appears to us as one of those archaic relics of traditional religion that Epicurus and Lucretius should have done their utmost to combat. Moral freedom and determinism are by no means incompatible. Man is himself a causal agent in nature and is morally responsible when he acts “freely,” i.e., from his own settled character and in his own capacity as an individual, provided he is exempt from external force or pressure.
His settled character may be partially determined by inherited psychological traits and by environmental influences, but as a causal agent in his own right he has some capacity to alter himself in one direction or another. In general the modern tendency is to regard moral freedom not as freedom from determinism but as freedom from coercion (such as physical force and the various pressures exerted by governments, corporations, and society itself).
. On the nullity of death and hell, see Lucr. 3.445–73, 3.861–69, 919–30, 978–1010 (=Men.
L25 and L26).
49–50. Note that certain images may bypass the senses and enter the mind directly. This occurs when we dream or when we contemplate the divine beings whom we can never perceive with any of the senses. We may dream, for example, of a dead friend, and see and talk to him. In such a case the images are not fallacious; they are free-floating films that have persisted from times when the friend was still living. Cf. Lucr. 4.757–76.
. “The fact of sensation itself universally attests that there are bodies, and it is by reference to sensation that we must rationally infer the existence of imperceptible bodies,” or atoms (Herod.
. Cf. Lucr. 4.482–85: “What should we consider as having greater validity than sensation? Will reasoning that takes its rise from ‘false’ sensation have power to contradict the senses when it originates wholly from them? If they are not true, all reasoning likewise becomes false.” Lucretius devotes a long passage (4.379–521) to the infallibility of the senses and the false inferences we
draw from sensory data. The example of the round tower was suggested by Lucr. 4.353 ff.
. This whole development, both religious and philosophical, is beautifully sketched out by Gilbert Murray in his Five Stages of Greek Religion
(New York, Columbia University Press, 1925); see especially Chap. III and IV, “The Great Schools” and “The Failure of Nerve.” Many centuries later Kant was equally alarmed by contemporary eighteenth-century developments, especially the devastating skepticism of Hume, and took the appropriate dogmatic steps to rehabilitate the validity of scientific knowledge.
. Especially by Professor De Witt in his recent important study of Epicurus; see Norman W. DeWitt, Epicurus and His Philosophy
(Minneapolis, University of Minnesota Press, 1954), pp. 7, 26, and elsewhere. See notes 27 and 29 to Diogenes Laertius’ Life of Epicurus
for a fuller treatment of his objections.
38; cf. also Herod.
82, where “our immediate feelings and sensations” and “our existing clear and distinct perceptions” are listed as definitive criteria.
. See the important quotation on this point from L.D.
24, given in full in IV. 4, above.
. Cf. also Lucr. 1.423–25: “Unless there is a fundamental and persistent faith in the sensations we have in common, there will be nothing to which we can resort when we attempt a rational demonstration of difficult questions.”
. Diogenes Laertius, Life of Epicurus
32 and 33. Cf. also Lucr. 4.478–79, “You will find that the concept of truth arose first from the senses and that the senses cannot be refuted.” For Professor De Witt’s antiempirical views see notes 27 and 29 to the Life of Epicurus.
. See Pyth.
90 and Lucr. 2.1118–45 (=L18).
80. Cf. also Pyth.
87: “From terrestrial phenomena it is possible to derive certain indications of what takes place in the heavenly bodies. It can be observed how the former occur but not how celestial phenomena occur, because it is possible for the latter to happen from a variety of causes.” Analogy was also used to draw inferences about the subempirical. Epicurus’ atoms “fall” through infinite space by analogy to falling bodies on earth, and in Herod.
59 inferences are drawn concern
ing the minimal parts of the atom by analogy to “perceptual minima,” i.e., the smallest points that can be seen by the naked eye.
Lucretius abounds in analogies, some prosaic and commonplace, others poetic or merely decorative. For example in 2.317 ff. we have the beautiful picture of sheep grazing on a distant hillside. They appear as a statio...