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Anaxagoras

Anaxagoras

The Greek philosopher Anaxagoras (ca. 500-ca. 428 B.C.) was the first to formulate a molecular theory of matter and to regard the physical universe as subject to the rule of rationality or reason.

Anaxagoras was born on the Ionian coast of Asia Minor in the town of Clazomenae, near Smyrna (now Izmir, Turkey). Nothing is known about his life before the age of 20, when he began to study philosophy. About 462 he moved to Athens, which was rapidly becoming an attractive cultural center. Anaxagoras was the first philosopher to take up residence in Athens. His teachings influenced the playwright Euripides, but his most famous pupil was Pericles, who dominated the political life of Athens during the 30 years Anaxagoras lived there.

Anaxagoras did not believe that the sun and moon were divinities, as the Greeks did, and he was prosecuted for his teachings. He returned to Asia Minor to a town allied with Athens, Lampsacus (now Lapseki, Turkey). Here he was treated with respect, and his memory was still honored a century after his death.

"About Nature"

Anaxagoras's views are preserved only in excerpts and summaries, more or less authentic. His book, written in prose, was entitled About Nature. It started with this assertion: "All things were together, infinite in number." This abrupt beginning was intended as a blunt contradiction of an earlier contention that the universe was "one continuous whole, which was not in the past," there being only an everlasting unchanging present. In direct opposition to this perpetually static monism, Anaxagoras propounded a constantly changing pluralism. He was the first philosopher to declare the number of separate things to be infinite (the universe as a whole having already been described as infinite).

Each of Anaxagoras's infinitely numerous separate things could be divided and further subdivided endlessly. All the things that were together were infinite not only in number but also in smallness: "Of what is small, there is no smallest part, but always a smaller." By contrast with the thinkers who maintained that matter consisted of those smallest units which were the atoms or indivisible particles, Anaxagoras believed in the infinite divisibility of matter. Nevertheless, as often as this process of subdivision was repeated, the resulting product always emerged as a unit of matter, however infinitesimally small it might be. In this sense Anaxagoras may be regarded as the author of the first molecular theory of matter.

Concept of Mind

His infinitely divisible things, infinite in number, were originally all together. How they had come together and where they had come from were questions not propounded by Anaxagoras. Thus, his universe began with a vast indiscriminate jumble or species of magma, which in the course of time was set whirling by Mind: "The whole rotation was controlled by Mind in such a way that in the beginning there was a vortical motion. At first the turning began on a small scale, but it spins more widely and it will spin even more widely."

What is more, Anaxagoras's Mind itself was not an insubstantial, incorporeal, exclusively mental, spiritual, or divine entity. Unlike a theist, Anaxagoras described his cosmic Mind as being the "most delicate and purest of all things." Nor was Anaxagoras a dualist in the conventional sense of one who counterposes mind against matter, for he declared that "Mind even now is where all other things are too, in the surrounding plenitude as well as in the things that have been assembled and those that have been disassembled."

Anaxagoras rebuked "the Greeks for not thinking correctly about birth and death, since nothing is born or dies; on the contrary, everything is assembled out of existing things and then dissolved. Accordingly, the Greeks would properly call birth 'combination' and death 'dissociation."' In other words, any individual thing comes into being by combining preexisting components and is dissolved into its constituent parts when its existence is terminated. While individuals come and go, the building blocks or molecular particles persist. They move about freely and enter into new combinations without undergoing any change in their essential nature.

This unceasing flux of migration, combination, dissolution, and recombination is not senseless or chaotic. For Anaxagoras, cosmic Mind "is infinite and absolute; it possesses perfect knowledge of everything, exerts the greatest power, and dominates all living things, the biggest and the smallest." Since all life in Anaxagoras's universe is under the control of Mind, each molecular interchange occurs according to rule. His universe therefore is thoroughly rational, and what he called "Mind" is analogous to what was afterward termed the "laws of nature."

Split-Level Universe

To this overall vision of an orderly cosmos, Anaxagoras contributed some valuable details. Of these, unquestionably the most spectacular was his discovery that the moon does not shine by its own light. By contrast, in the Hebrew Bible the moon was the lesser of the two great lights; like the sun, which was the biblical greater light, the Hebrew moon was self-luminous. Presumably it is because the earth too receives light from the sun that Anaxagoras declared the moon to be earth. His earth and moon resembled each other also in having "flat areas and depressions." Anaxagoras's amazingly prescient description of the moon's ups and downs and his implicit denial that the lunar surface was perfectly spherical waited more than 2,000 years for visual confirmation by Galileo's telescope, and then more than 3 additional centuries for the direct physical proof provided by the American astronauts on the moon.

Anaxagoras believed (mistakenly) that the sun was a red-hot stone. Apparently generalizing from the instances of the sun and moon, he asserted that all the heavenly bodies were stone. His opinion that rock was the material of those bodies may have been inspired by the fall of a huge meteorite, said to have been as big as a wagon, near the Dardanelles when he was a young man. Since Anaxagoras correctly classified the meteorite as an object fallen from the sky to the earth, his universe was all alike. Later the cosmos was divided into an ethereal heaven, reserved for divinities, and the coarse earth, to which mere mortals were consigned. The painful process of reunifying this post-Anaxagorean split-level universe amounted to a return to the one world of Anaxagoras.

Further Reading

Daniel E. Gershenson and Daniel A. Greenberg, Anaxagoras and the Birth of Physics (1964), is a collection of the ancient references to Anaxagoras, arranged in chronological order and analyzed as to content; the bibliography is annotated. Also useful is Felix M. Cleve, The Philosophy of Anaxagoras (1949). Among the general books on early Greek philosophy that discuss Anaxagoras are John Burnet, Early Greek Philosophy (1892; 4th ed. 1930); Theodor Gomperz, Greek Thinkers: A History of Ancient Philosophy (3 vols., 1896-1909; trans., 4 vols., 1901-1912); and G. S. Kirk and J. E. Raven, The Presocratic Philosophers: A Critical History with a Selection of Texts (1962).

Additional Sources

Schofield, Malcolm., An essay on Anaxagoras, Cambridge Eng.; New York: Cambridge University Press, 1980.

Anaxagoras., The fragments of Anaxagoras, Meisenheim am Glan: Hain, 1981. □

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Anaxagoras

Anaxagoras

(b. Clazomenae, Lydia, 500 B.C.[?]; d. Lampsacus, Mysia, 428 b.c.[?])

natural philosophy.

Although he was born of wealthy parents, Anaxagoras neglected his inheritance to devote himself to natural philosophy. At the age of twenty, he traveled to Athens, where he spent the next thirty years. There he became a friend of Pericles and brought Ionian physical speculation to Athens at the height of its intellectual development. Subsequently he was prosecuted for impiety and banished1 because, it was alleged, he held the sun to be a mass of red-hot stone. This charge doubtless was instigated by the political opponents of Pericles, who sought to attack him through his friendship with an atheistic scientist. Anaxagoras wrote only one treatise, completed after 467 b.c.

Like Empedocles, Anaxagoras sought to reconcile Parmenides’ logic with the phenomena of multiplicity and change. Each maintained that there was never a unity in either the qualitative or the quantitative sense and postulated instead a plurality of eternal, qualitatively different substances that filled the whole of space. They accepted Parmenides’ negation of coming-into-being and passing-away but replaced the former with the aggregation of their indestructible elements and the latter with their segregation. Motive forces were introduced to account for motion—a phenomenon whose validity had, prior to Parmenides, been taken for granted.

Anaxagoras evidently did not consider that Empedocles had fully satisfied the demands of Eleatic logic.2 Empedocles had seen no objection to making secondary substances come into being as various combinations of his elements. A piece of flesh, according to him, consisted of the four elements juxtaposed in almost equal quantities. Theoretically, if it were divided, one would arrive at a minimum piece of flesh and thereafter at particles of the constituent elements. Thus, flesh originally came into being from the elements and, strictly speaking, from what is not flesh. Anaxagoras’ own formulation of the problem is preserved: “How,” he asks, “could hair come to be from what is not hair and flesh from what is not flesh?” (Diels and Kranz, B10). His answer was to claim that everything preexisted in our food. Thus, he denied the existence of elements simpler than and prior to common natural substances and maintained that every natural substance must itself be elementary, since it cannot arise from what is not itself. Furthermore, to avoid being confuted by Zeno’s paradoxes against plurality, he held that matter was infinitely divisible; that however far any piece of matter might be divided, there always resulted smaller parts of the same substance, each of which always contained portions of every other substance3 and was itself capable of further division. Its predominant ingredients were responsible for its most distinctive features.

Initially, Anaxagoras held, all things were together in an apparently uniform, motionless mixture. Then Mind (Nov̂s) instituted a vortex, causing the dense, wet, cold, and dark matter to settle at the center and the rare, hot, and dry matter to take up peripheral positions as the sky. From the former, the disklike earth was compacted (Diels and Kranz, B15–16). The sun, moon, and stars, however, were torn from the earth and carried around, ignited by friction.4

Although strikingly rational, Anaxagoras’ astronomy was not fruitful because it provided no stimulus to discover the laws of planetary motion. A more important contribution was his concept of a separate, immaterial moving cause, which paved the way for a fully teleological view of nature.5 His theory of matter, however, was not influential, doubtless as much because of its subtlety and sophistication as because of its lack of economy.

NOTES

1. For the chronology of Anaxagoras’ life see Taylor, Davison, and Guthrie.

2. For the relative dating of the works of these two see Longrigg, p. 173, n. 49.

3. The interpretation of Anaxagoras’ theory is highly controversial. Certain scholars, most cogently Vlastos, reject this so-called naïve interpretation on the grounds that it involves a redundancy and an infinite regress. Their solution, although plausible, is, however, less in accordance with the fragments. On the question of the regress see especially Strang, pp. 101 ff.

4. The fall of the meteorite at Aegospotami in 467 b.c. probably suggested this theory. (It might be observed here that although Anaxagoras is commonly stated to have been the first to discover the true explanation of eclipses, there is evidence against his priority.)

5. For the reaction of Plato and Aristotle see Phaedo 97B and Metaphysics 985a 18 ff. (Diels and Kranz, A47).

BIBLIOGRAPHY

The collected fragments and later testimony are in H. Diels and W. Kranz, Die Fragmente der Vorsokratiker, 6th ed. (Berlin, 1951–1952), II, 5–44.

Secondary literature includes C. Bailey, The GreekAtomists and Epicurus (Oxford, 1928), pp. 537–556; D. Bargrave–Weaver, “The Cosmogony of Anaxagoras,” in Phronesis, 4 no. 2 (1959), 77–91: J. Burnet, Early, Greek Philosophy, 4th ed. (London, 1930), pp. 251–275; W. Capelle, “Anaxagoras,” in Neue Jahrbücher für das klassische Altertum (1919), 81–102, 169–198; F. M. Cleve, The Philosophy of Anaxagoras (New York, 1949); F. M. Corn–ford, “Anaxagoras’ Theory of Matter,” in Classical Quarterly, 24 (1930), 14–30, 83–95; J. A. Davison, “Protagoras, Democritus and Anaxagoras,” ibid., n.s. 3 (1953), 33–45; O. Gigon, “Zu Anaxagoras,” in Phiologus, 91 (1936–1937), 1–41; W. K. C. Guthrie, A History, of Greek Philosophy. II (Cambridge, England, 1965), 266–338; G. S. Kirk and J. E. Raven, The Presocratic Philosophers (Cambridge, England, 1957), pp. 362–394; J. Longrigg, “Philosophy and Medicine: Some Early Interactions,” in Harvard Studies in Classical Philology, 67 (1963), 147–175; R. Mathewson, “Aristotle and Anaxagoras: An Examination of F. M. Cornford’s Interpretation,” in Classical Quarterly, n.s. 8 (1958), 67–81; C. Mugler, “Le problème d’Anaxagore,” in Revue des ètudes grecques, 69 (1956), 314–376; A. L. Peck, “Anaxagoras: Predication as a Problem in Physics,” in Classical Quarterly, 25 (1931), 27–37, 112–120: J. E. Raven, “The Basis of Anaxagoras’ Cosmogony,” ibid., n.s. 4 (1954), 123–137; C. Strang, “The Physical Theory of Anaxagoras,” in Archiv Für Geschichte der Philosophic, 45 , 2 (1963), 101–118; P. Tannery, Pour l’historie de la science hellène, 2nd ed. (Paris, 1930), pp. 275–303; A. E. Taylor, “On the Date of the Trial of Anaxagoras,” in Classical Quarterly, 11 (1917), 81–87; G. Vlastos, “The Physical Theory of Anaxagoras,” in Philosophical Review, 59 (1950), 31–57; and M. L. West, “Anaxagoras and the Meteorite of 467 b.c.,” in Journal of the British Astronomical Association, 70 (1960), 368–369.

James Longrigg

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Anaxagoras

Anaxagoras (ăn´əksăg´ərəs), c.500–428 BC, Greek philosopher of Clazomenae. He is credited with having transferred the seat of philosophy to Athens. He was closely associated with many famous Athenians and is thought to have been the teacher of Socrates. His belief that the sun was a white-hot stone and that the moon was made of earth that reflected the sun's rays resulted in a charge of atheism and blasphemy, forcing him to flee to Lampsacus, where he died. Rejecting Empedocles' four elements (earth, air, fire, and water), Anaxagoras posits an infinity of particles, or "seeds," each unique in its qualities. All natural objects are composed of particles having all sorts of qualities; a preponderance of similar though not identical particles creates the difference between wood and stone. Anaxagoras' universe, before separation, was an infinite, undifferentiated mass. The formation of the world was due to a rotary motion produced in this mass by an all-pervading mind (nous). This led to the separating out of the "seeds" and the formation of things. Although Anaxagoras was the first to give mind a place in the universe, he was criticized by both Plato and Aristotle for only conceiving of it as a mechanical cause rather than the originator of order.

See D. E. Gershenson and D. A. Greenberg, Anaxagoras and the Birth of Physics (1964); M. Schofield, An Essay on Anaxagoras (1980).

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Anaxagoras

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