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(b. Athens [?], 427 B.C.; d. Athens, 348/347 B.C.)

theory of knowledge; advocacy, in theory and practice, of education based on mathematics; organization of research.

Plato’s enthusiasm for mathematics, astronomy, and musical theory appears everywhere in his writings, and he also displays a far from superficial knowledge of the medicine and physiology of his day. In ancient times competent judges held that he had promoted the advance of mathematics, especially geometry, in his lifetime.1 Theodore of Cyrene and Archytas of Tarentum were his friends, and Eudoxus of Cnidus, Theaetetus, and Menaechmus his colleagues or pupils. His critics assert that his theory of knowledge rules out any empirical science and that, owing to his idealism, he had a radically false idea of the procedure and value of the mathematics that he admired. Even so, it can be said that the Academy, founded by him at Athens at a date not exactly known (380 B.C.?), became a center where specialists—not all of them sympathizers with his philosophy and epistemology—could meet and profit by discussion with him and with one another.

Our object here must be to trace Plato’s intellectual development and, incidentally, to submit part of the material upon which an estimate of his services or disservices to science must be based. It must be considered how far he is likely to have carried out in his school the project, sketched in the Republic, of a mathematical training preparatory for and subordinate to dialectic, and whether, in the writings believed to belong to the last twenty years of his life, he took note of recent scientific discoveries or was influenced by them in matters belonging to philosophy.

As for sources of information, the account of Plato’s life and doctrine by Diogenes Laertius (probably early third century A.D.) is based on previous authorities of unequal value. He reports some evidently reliable statements by men who were in a position to know the facts and who were neither fanatical devotees nor detractors, and he has preserved the text of Plato’s will. Aristotle gives us a few details, and Cicero a few more.

The Epistles, ascribed to Plato and printed in the Herrmann and Burnet editions of the Greek text of his works, would, if genuine, furnish us with a personal account of his conduct at important crises in his life; and, what is more, they would tell far more about his ideals of education and the work of the Academy than can be gathered from the dialogues. Unfortunately, opinion regarding authenticity of the Epistles is so divided that caution is essential. In the ensuing account, where reference is made to this source, the fact has been indicated.

Plato’s writings have been preserved entire. But the double fact that they are dialogues and that the scene is usually laid in the past leads to difficulties of interpretation which are sufficiently obvious. Moreover, nothing definite is known about either the manner of their first publication or their relative order, still less the dates. Some hypothesis about the latter is a presupposition of fruitful discussion of Plato’s development.

A statistical study of the style of Plato’s works, in which the pioneer was the Reverend Lewis Campbell (1869), has led to results which have met with wide approval: many scholars hold that Parmenides and Theaetetus were written later than the Republic, and that a group of dialogues having close stylistic affinity to one another and to the Laws (which is plainly a work of old age) came still later. This is credible from a philosophical point of view, and its correctness is assumed here; but such a method can only yield a probable result.

Several members of Plato’s family are mentioned, or appear as characters, in his dialogues. He himself was the son of Ariston2 and Perictione, and was born either at Athens or Aegina, where his father may have gone as a settler when the Athenians occupied the island. Nothing reliable is known of his father’s ancestors, but those on his mother’s side were men of distinction. Perictione was descended from Dropides, a close friend (some say brother) of Solon, the famous poet-statesman of the sixth century B.C. She was a cousin of Critias, son of Callaeschrus, an intellectual daring in both speculative thought and action. It was Critias who in 404 B.C. led the extremists among the Thirty Tyrants and put to death the moderate Theramenes. He became guardian of Perictione’s brother Charmides and drew him into public affairs. Both perished in the battle which put an end to the Thirty’s six months of power.

Plato was one of four children. His brothers Adeimantus and Glaucon take a leading part in the Republic, where they are depicted with admiration and a clear impression of their personality is left. They appear once more briefly in the Parmenides, and Xenophon presents Socrates proving to Glaucon the folly of his trying to address the Assembly when he is not yet twenty.3 The brothers were considerably older than Plato, and his sister Potone (mother of Speusippus, who followed him as head of the Academy) was doubtless born in the interval.

Plato’s father, Ariston, appears to have died young. Perictione then married Pyrilampes, son of Antiphon, who had been prominent in state affairs as a close associate of Pericles; he was probably her uncle. Another son, called Antiphon after his grandfather, was born; this half brother of Plato’s has a part in the Parmenides. Most of these persons are mentioned either in Charmides (155–158), or in Timaeus (20E), or at the opening of Parmenides.4

Plato’s social position was such that he might well have aspired to an active part in public affairs, but it could not have been easy for him to decide what role to assume. Some scholars take it for granted that the example and writings of Critias left a deep impression upon him; others point out that it was only in the concluding phase of the Athenian struggle against the Peloponnesians that Plato’s maternal relatives emerged as reactionary extremists, and that in his stepfather’s home he would have been imbued with liberal opinions and respect for the memory of Pericles.

No one can say with certainty what the complexion of his views was at the age of twenty-four, except that he was obviously no friend to egalitarianism and full democracy. The story which he tells, or is made to tell, in Epistle VII seems probable. His friends and relatives among the Thirty at once called upon him to join them, but instead he determined to wait and see what they would do. They soon made the former regime seem highly desirable by comparison. Socrates was commanded to help in the arrest of a man who was to be put to death illegally under a general sentence, so that he would either be involved in their impious actions or refuse and thus expose himself to punishment. When the Thirty were overthrown, Plato again thought of public affairs—but with less eagerness than before. The democratic leaders restored to power showed moderation at a time when ruthless acts of revenge might have been expected. Nevertheless Socrates was brought to trial on the pretext of impiety and found guilty. As Plato grew older and the politicians, laws, and customs of the day displeased him more and more, he was thrown back on a theorist’s study of ways of reform.5

None of this is inconsistent with what is otherwise known. Socrates’ disobedience to the illegal command of the Thirty was a fact widely spoken of. Plato would probably have been impressed to an equal degree by Socrates’ courageous independence in such matters and by his faith in argument (argument with himself when he could not find a respondent). He became conspicuous among Socrates’ habitual companions, as distinct from the occasional listeners to his conversation. With Adeimantus he heard Socrates’ provocative defense in court against the charge of impiety;6 when a majority had found him guilty, Plato was one of those who induced Socrates to offer to pay a substantial fine, for which he would be a guarantor.7

Owing to illness, Plato was absent from the last meeting of Socrates’ with his friends.8 After the tragedy, he retried, with other Socratics, to Megara, the home of Euclid.9 The attack on Socrates was personal, and perhaps the prosecutors did not desire his death. His Athenian friends can hardly have been in danger. But there are some hints in the Phaedo that he advised those present, among whom were the Megarians Euclid and Terpsion, to pursue the search for truth in common and not lose heart when plausible reasoning led them nowhere; rather, they must make it their business to master the “art of argument,” logōn techuē.10

Probably his wish was piously carried out by his followers, and a few years elapsed before the different direction of their interests became clear. As a metaphysician Euclid was a follower of Parmenides, and accepted the Socratic thesis that there is a single human excellence, not a plurality of “virtues.” His thought had no religious coloring, nor was he an educational reformer. His younger disciples turned in earnest fee the hoped-for logon techne, and not without result; they prepared the way for the propositional logic of the Stoic school.11 This might be supposed to go together with an interest in the sciences, but this is not recorded of the Megarians. Plato, on the other hand, began to turn in that direction; his first dialogues and the Apology must have been written during the years 399–388 B.C. He felt it his duty to defend the memory of Socrates, especially since controversy about his aims had been revived by hostile publications. As the chance of political action remained remote, he gradually developed the idea of a training of the young not in rhetoric but in mathematics—and in Socratic interrogation only after the mathematical foundation had been laid. Part of his diagnosis of the ills of Athens was that young men had bewildered themselves and others by engaging too soon in philosophical controversy; these ideas probably found little sympathy among the Megarians. How long he remained among them is not recorded, but he was liable to Athenian military service, probably as a cavalryman. A statement has indeed come down to us 12 that he went on expeditions to Tanagra (in Boeotia) and Corinth. This is credible in itself, and in the latter case the reference could be to an engagement in 394 B.C. outside Corinth, in which the Spartans and their allies defeated the Athenians and Thebans. But neither does it seem inconsistent with Plato’s regarding Megara for a time as his home. About 390 he resolved to visit the West, where Archytas of Tarentum survived as a maintainer of the Pythagorean system of education and was also active in research.

Plato’s views at the time of departure on his journey to the West are well seen in the Gorgias. It is his first major constructive effort as a moralist, but there is as yet no positive doctrine of knowledge and reality. When Callicles spurns conventional justice, as a means of defrauding the strong and energetic of what naturally belongs to them, and declares that temperance is not a virtue (why should a clear-sighted man choose to curb his own desires?), Socrates confidently develops an answering thesis: the supervision of the soul must be supposed comparable in its operation to the arts, which impose form and design (eidos, taxis) and preserve the natural subordination of one part of a subject to another (kosmos). Human good does not consist in the ceaseless satisfaction of desires, irrespective of their quality (if it did, man would stand apart from the general world order), and self-discipline is the basis of happiness. But the statesmen of Athens, the dramatists and musicians, the teachers and learners of rhetorical persuasion, have all alike failed to understand this and have flattered rather than guided the public.

In his use of the varied senses of kosmos (which, according to the context, means world or world order, moral discipline, or adornment). Socrates is here on Pythagorean ground; and ideas are already present which Plato expanded only in his later writings and his oral instruction.13 The Gorgias passage is also an emphatic answer to the friends who had sought to draw Plato into Athenian politics.14

Concerning the journey itself, in Epistle VII Plato says, or is made to say, that he was then forty years old (324A) and that in Italy and Sicily he was appalled by the sensuous indulgence which he found taken for granted there. On crossing to Syracuse he made the acquaintance of Dion, the young brother-in-law of the tyrant Dionysius the Elder, who listened attentively to his discourses and aroused his admiration by his intelligence and preference for a sober life. In the tyrant’s entourage this was viewed as an affectation of singularity and led to Dion’s becoming unpopular.15

If this evidence is set aside as suspect, the next best source is Cicero.16 He says that Plato visited Egypt before proceeding to Italy; that he spent a considerable time with Archytas and with Timaeus of Locri; and that the object of the voyage was to gain acquaintance with Pythagorean studies and institutions. To this some reservations must be made. First, it can hardly be true—if Cicero means this that when he boarded the ship Plato was altogether ignorant of mathematics. In his own dialogues there is clear evidence that the sciences were to some extent taught to boys at Athens and that there was an opportunity of learning from specialists in mathematics and astronomy, no less than from those in music, meter, and grammar. About Pythagoreanism also Plato already had some information, judging from the Gorgias passage mentioned above; he could have obtained this (as Wilamowitz suggests) from the Thebans Simmias and Cebes, pupils of Socrates who are said to have met Philolaus.17

Secondly, it does not seem likely that Timaeus of Locri was still alive at the time of Plato’s journey. In Timaeus 20A he is described as a man of intellectual distinction who has already held high office, and this is at a time certainly previous to 415 B.C. (It is possible that at this time Plato met Philistion of Locri, and derived from him the interest in the physiology of the Sicilian Empedocles, which is visible in both Meno and Phaedo) Cicero’s report may be wrong in some of its detail, but it seems true in spirit. Plato’s purpose in visiting the West was to see for himself how the Pythagoreans conducted their science-based educational system, and he did at this time establish a connection with Archytas.

Plato returned to Athens, after two years’ absence, in 388 B.C. (Ancient biographers related, with some circumstantial detail, that at Syracuse he had exasperated the tyrant Dionysius the Elder by open criticism of his rule and had been handed over as a prisoner to a Spartan envoy. But such insolence is hardly in character for Plato, and probably his voyage home was of a less sensational kind.) He might at this time have visited the Pythagoreans at Phlius, in the Peloponnesus. The setting of the Phaedo suggests personal acquaintance with their leader Echecrates, and Cicero confirms this.18

Nothing definite is recorded about Plato’s personal life during the ensuing twenty-two years. But the Academy was founded, or gradually grew up, during this time, and he composed further dialogues in Socratic style. The Meno and Euthyplwo, Euthydemus. Phaech, Symposium, and Republic must all be assigned to these years. In them he puts forward the distinctive account of knowledge which has taken shape in his mind; explains his purpose and method in education and shows the continuity of his aims with those of Socrates; and differentiates himself, where necessary, from the Italian Pythagoreans. It is natural to place the Republic at the end of this series, and to regard it as either a prospectus for a proposed school or as a statement to the Athenian public of what was already being carried out among them.

Aristotle gives a clear analysis of the factors which produced Plato’s doctrine of Forms.19 Plato was acquainted from youth with an Athenian named Cratylus, who declared with Heraclitus that there is no stable substance, or hold for human knowledge, in the sense world. Plato did not deny this then or later but, wishing to take over and continue the Socratic search for universals, in the sphere of morals, which do remain permanent, he necessarily separated the universals from sensible particulars. It was he who termed them Ideas and Forms. In his view particulars (that is, things and states of things, actions and qualities) derive reality from Forms by “participation” and when we name or speak of these particulars, we in effect name Forms.

In the dialogues Plato often starts from a contrast between knowledge and opinion. To live in a state of opinion is to accept assertions, either of fact or of principle, on authority or from mere habit. The opinion may be true and right; but since it is held without a rational ground, it may be driven from the mind by emotion and is less proof against forgetfulness than knowledge is. The holder of it may also be deceived in an unfamiliar instance. Based as it is on habit, an opinion cannot easily be transmitted to another; or, if the transmission takes place, this is not teaching. In terms of the theory of Forms, the holder of knowledge knows the Forms and can relate particular instances to them (although Plato did not successfully explain how this occurs), whereas the contented Holder of opinions moves about among half-real particulars.

In middle life, then, Plato had advanced from his Socratic beginnings toward beliefs, held with assurance, from which many practical consequences flowed. The chief elements were the knowledge-opinion contrast; the belief in a realm of immutable Forms, with which human minds can make intermittent contact and which on such occasions the minds recognize as “their own” or as akin to them;20 given this, the soul, or its intellectual part, is seen to be likewise eternal; and the belief that the Forms, each of which infuses reality into corresponding particulars, in turn derive their existence, intelligibility, and truth from one supreme Form, the Good.

The advance from the plurality of Forms to their source is in consequence regarded as the ultimate stage in human study, megiston mathēma;21 it is a step which will be taken by only a few, but for the welfare of mankind it is important that a few should take it. Within the dialogue it is described but cannot be accomplished. There are hints of a methodical derivation of the other Forms from the Good; but for the present the image, whereby the Good is shown to have the same relation to other objects of intellection as the sun has to other visible things, takes its place. In reading the Republic and later dialogues, one must therefore reckon with the possibility that in the school Plato amplified or corrected the exposition which he chose to commit to writing.

The Athenians thought it suitable that young men should exercise themselves in argument on abstract themes before turning to serious business, and were prepared to tolerate “philosophy” on these terms. But Plato, as has been said, speaks out against this practice and holds that it has brought philosophy into discredit. Indeed, according to him, the order of procedure should be reversed. Argument, or its theory, is the hardest branch of philosophy and should come later. Men and women to whom legislation and administration are ultimately to be entrusted should undergo discipline in the sciences (including reflection on their interrelation) before they embark, say, at the age of thirty, on dialectical treatment of matters which have to be grasped by the intellect without the help of images. Such a discipline will single out those who have capacity for dialectic. To them will fall the task of making good laws, if these are not found in existence, and of interpreting and applying them if they are. For this purpose knowledge must be reinforced by experience.22 Lawless government is the common fault of despotism and democracy.

Plato holds that ignorance of mathematical truths which are in no way recondite, for example, the wrong belief that all magnitudes are copoensurable, is a disgrace to human nature.23 It is not, however, this that is emphasized in his educational plan in the Republic. He explains that it is characteristic of mathematical studies that they gently disengage the intellect from sensible appearances and turn it toward reality; no other discipline does this. They induce a state of mind (which Plato terms dianoia, discursive thought) clearer than “opinion” and naive trust in the senses but dimmer than knowledge and reason. In geometry, for instance, the learner is enabled or compelled, with the aid of figures, to fix his attention on intelligible objects. Also, mathematicians “lay down as hypotheses the odd and even, various figures, and the three kinds of angles and the like”24 but leave them unexamined and go on to prove that the problem that gave rise to their investigation has been solved. In this respect mathematical procedure tends to divert the mind from reality and can provide only conditional truth. But such studies, pursued steadily and without continual talk of their practical use, are a good preparation for methodical treatment of such relations among Forms as cannot be visibly depicted.

Arithmetic and plane geometry will be the basis of an education which is to end in knowledge; the geometry of three-dimensional figures must also be studied. When, in the dialogue, Glaucon observes that this hardly yet exists as a science, Socrates says that there are two reasons for this: first, no state at present honors the study and encourages men to devote themselves to it; and second, a director is needed in order to coordinate the research.25 Such a man will be hard to find; and at present even if he existed the researchers are too self-confident to defer to him. Even without these conditions, and even when the researchers do not succeed in explaining what they are striving to achieve, the intrinsic charm of the study of three-dimensional figures is carrying it forward. This is one of the passages in which speakers in Plato’s dialogues refer prophetically, but in veiled terms, to circumstances at the time of writing. It is somewhat enigmatic for us. The intention is perhaps to compliment Theaetetus, who had discovered constructions for inscribing in a sphere the regular octahedron and icosahedron. Either he or Plato himself is cast for the role of a director, and there is a plea for public support of the Academy so that research can continue.

There is a similar personal reference in the treatment of the sciences of astronomy and musical theory.26 Socrates dissociates himself from the Pythagoreans while approving of their statement that the two sciences are closely akin. Their theory of harmony is restricted to a numerical account of audible concords; and the aim of their astronomy is to discover the proportion between month, year, and the period of revolution of the planets. Instead of this, heard harmonies should be studied as a special case of the harmonies between numbers; and the proportion between month, year, and so forth (which is doubtless not unvarying) as an application of some wider theory dealing with the spatial relations of any given number of bodies of any shape, moving at any regular speeds at any distances. The visible universe will be to the “true astronomer” what a beautifully contrived diagram might be to the geometer, that is, an aid to the science, not the object of contemplation. Here Plato is indicating that he has not simply established on Athenian soil a replica of the Pythagorean schools. Attachment to the sense world must be loosened and the sciences taught with emphasis on their affinity to one another; for it is the power of synopsis, the perception of common features, that is to be strengthened. Those few who excel in this are to be set apart and trained to pursue another method which treats hypotheses as provisional until they have been linked to the unconditionally real and so established.27

There is no question here, as some have thought, of a fusion of the existing special sciences. The ideal held out is probably this: The One is an aspect of the Good (this was common ground to Euclid of Megara and Plato); from the concept of unity, the number series can be made to emerge by deduction; and from the Good, by a process which makes more use of Socratic questioning, the system of moral and aesthetic concepts can likewise be evolved.28

Boys will have some introduction to all the sciences that have been mentioned. Compulsion is to be avoided in the training of the mind, especially since what is learnt under duress leaves no lasting impression. At the age of twenty when state-enforced physical exercise is to cease, those judged capable of further progress must begin to bring together the knowledge that they have hitherto acquired randomly and to consider in what way the sciences are akin to one another and to reality. Until they are thirty this will be their occupation. After this there can follow five years of that dialectical exercise that Athenian custom regards as a fitting occupation for mere adolescents.29

The program here outlined is our safest guide to the actual institutions of the Academy. But it is an ideal that is sketched, and one need not insist that it was carried out in detail. For instance, Plato did not admit women, and it is highly improbable that he gave no philosophical instruction to those under thirty; it would doubtless occur to him that since he could not prevent them from obtaining such instruction, it would be better to make sure that they were well taught.

“Academy” was an area to the northeast of the city which had been laid out as a park, including a public gymnasium. According to Lysias, the Spartans encamped there during the troubled year 403 B.C. Plato may have copoenced teaching in the gymnasium itself; but he soon purchased an adjoining garden and erected buildings there, and from this moment he may be said to have instituted a school. Hitherto he could not exclude chance listeners. The buildings may have included lodgings for students or visitors, and Plato himself presumably lived in the neighborhood. Common meals had been a feature of Pythagorean life, and this precedent was followed. Legal recognition was secured by making the Academy a religious fraternity devoted to the Muses.

Plato nominated his nephew Speusippus to be his successor, but later the head seems to have been elected. Presumably the power of admission rested with the head, and those accepted contributed to the maintenance of the school according to their means. The story that the words “Let no man unversed in geometry enter” were inscribed over the door cannot be traced back further than John Philoponus (sixth century). In the first century B.C., “academic” teaching was being given in the gymnasium of Ptolemy near the agora of Athens.30

In the teaching, Plato will doubtless have been assisted from an early stage by Theaetetus, who, as the dialogue named after him shows, was a boy of exceptional promise in 399 B.C. He was an Athenian. The dialogue records his death from wounds received in battle at Corinth, complicated by illness, and was obviously written soon afterward (ca. 368–367 B.C.). Hence his collaboration with Plato may have lasted about fifteen years.

Somewhat later, Eudoxus of Cnidus resided occasionally at the Academy. He is known to have died at the age of fifty-three, and the dates for his life now usually accepted are ca. 400-ca. 347 B.C. in mathematics he was a pupil of Archytas, but it is not clear when this instruction was received. During a first visit to Athens at the age of twenty-three, he heard lectures from Plato. Later he established a school at Cyzicus in northwest Asia Minor, one of those Greek cities which had been abandoned to Persian control under the Peace of Antalcidas in 387 B.C.; Eudoxus probably felt insecure there and was glad to maintain a connection with the Platonists.

Eudoxus was at Athens when Aristotle first arrived as a student in 367 B.C., and it is plain from several Aristotelian passages31 that he deeply influenced his juniors and played an important part in the life of the school. In Plato’s Philebus there is probably some concealed allusion to him. Mathematics and astronomy were his main business, but he took part as a friendly outsider in philosophical debate arising from Plato’s writings. He was not one to pledge himself to accept philosophical dogmas, nor was this expected of him, and his work exhibits the close attention to phenomena which the Socrates of the Republic deprecates.

But Eudoxus recognized that philosophy has a legitimate role in criticizing the procedure of specialists. His explanation of the celestial movements in terms of homocentric spheres, rotating about a stationary spherical earth, was put forward in answer to a problem posed by Plato: “What are the uniform and ordered movements by the assumption of which the apparent movements of the planets can be accounted for?” Eudoxus did not abandon his own school and merge it with that of Plato; and Proclus’ statement that he “became a companion of Plato’s disciples” does not mean this, for we know that Aristotle later carried on the connection with Cyzicene mathematicians which Plato had established. Epistle XIII, ascribed to Plato, mentions Helicon as a pupil of Eudoxus and implies the presence of other Cyzicenes at Athens in the period 365–362 b.c.

If we consider Plato’s relation to Theaetetus and Eudoxus and also bring in the evidence of Aristotle, his personal role in the Academy begins to appear. He probably committed all the specialist instruction to them. He took note of their research and sometimes criticized their methods, speaking as a person with authority; he guided the juniors in that reflection about first principles and about the interrelation of sciences that in Republic VII is designated as suitable for them;32 and he confided to some an ethico-mathematical philosophy in which two ultimate principles, from which Form-Numbers were derived, were found by analysis.

The last item is outside the scope of this article, and concerning the other two a few examples must suffice. Theaetetus added to previously known constructions of regular solid figures those for the octahedron and icosahedron, and gave a proof33 that there can be no more than five regular solids. He also tried to classify incopoensurable relations, connecting them with the three kinds of means. Plato’s inspiration may be seen in this effort to systematize. Plato is credited by Proclus with beginning the study of conic sections, which his followers developed, and with either discovering or clearly formulating the method of analysis, which proved fruitful in geometry in the hands of Leodamas of Thasos.34 According to Plutarch, Plato criticized Eudoxus, Archytas, and Menaechmus for trying to effect the duplication of the cube by mechanical means and so losing the benefit of geometry.35 Aristotle says that Plato (in oral instruction) “used to object vigorously to the point, as a mathematical dogma, and on the other hand often posited his indivisible lines.”36

The view that the sciences contemplate objects situated halfway between Forms and sensibles and having some of the characteristics of both, which is not found in Plato’s dialogues, was probably at home in the same discussion. Observation of the heavens went on, perhaps under the direction of Eudoxus or his companions. Aristotle says that he had seen an occultation of Mars by the moon (then at half-moon); this must have been in April or May 357 B.C., a calculation first made by Kepler.37

It was maintained by H. Usener in 1884 that the Academy was the first known institute for scientific research, a statement which initiated a debate not yet closed. It has been opposed from one point of view by those who compare the Academy to a modern school of political science (and perhaps jurisprudence) thoroughly practical in its orientation; and from another especially by Jaeger, who thinks that it was no part of Plato’s intention to teach science in encyclopedic fashion and promote its general advance.38 The Academy was not a place in which all science was studied for its own sake but one in which selected sciences were taught and their foundations examined as a mental discipline, the aim being practical wisdom and legislative skill, which in Plato’s opinion are inseparable from contemplative philosophy.

Evidently the crux of this matter is whether empirical sciences, which had no place in the curriculum projected for the guardians in the Republic, were, in fact, pursued under Plato’s auspices. Jaeger seems to be right in his skepticism about the apparent evidence of such activity. It may be added that proofs that Plato was personally interested in (for instance) medicine and physiology, which Timaeus affords, are not quite what is wanted. One might argue that he was indeed an empirical scientist manqué, pointing to his interest in the manufacturing arts in the Statesman, his marvelous sketch of the geology of Attica in the Critias, and his attention to legislative detail in the Laws. It was an imperfectly suppressed love of the concrete and visible, rather than any retreat from his avowed opinions, that led him to pose the problem concerning celestial phenomena which Eudoxus later solved. But it is a long step from these admissions to the pronouncement that the Academy became an institute of scientific research.

Plato’s activity at Athens was interrupted by two more visits to Sicily. When Dionysius the Elder died in the spring of 367 B.C., two problems in particular demanded solution: what the future form of government Syracuse itself should be; and when and how several Greek cities, whose populations had been transferred elsewhere under Dionysius’ policy, should be refounded. Plato’s admirer Dion planned to make his nephew, Dionysius the Younger, a constitutional monarch, and appealed for Plato’s aid in educating him for his responsibility. His proposal was that Plato should come to Syracuse and take charge of a group of earnest students, which Dionysius might unobtrusively join.

Plato yielded to pressure and arrived in the spring of 366 b.c. But, according to Epistle VII, he found a situation of intrigue. Some Syracusans believed that Dion’s aim was to occupy his nephew with interminable study while he himself wielded effective power. From another side there was pressure for the restoration of full democracy. A war with Carthage (or against the Lucanians) was in progress. Three months after Plato’s arrival the young ruler charged Dion with attempting to negotiate with the Carthaginians and expelled him. Plato left the following year (365 b.c.), after obtaining what he took to be a promise that Dion would be recalled.

In 362 b.c. he once more left the Academy (appointing, it is said, Heraclides Ponticus as his deputy) and returned to Syracuse. There were reports that Dionysius was now genuinely interested in philosophy; but in consenting to go Plato was more influenced, according to Epistle VII, by a promise that a favorable settlement of Dion’s affairs could be reached on condition that he return. Dion had spent his years of exile in Athens and had become a friend of Plato’s nephew Speusippus.

Plato’s mission ended in failure. Dion’s agents were forbidden to send him the revenue from his estates; and Plato made his escape with some difficulty, returning home in 361 b.c. Dion thereupon took steps to effect his return to Syracuse by force, urging Plato to aid him and to punish Dionysius as a violator of hospitality. But Plato answered (still according to the Epistle) that he was too old, that after all Dionysius had spared his life, and that he wished to be available if necessary as a mediator. Other members of the Academy, however, joined the expedition. Dion succeeded in his enterprise but failed to reconcile the warring parties; and after a brief period of power he was murdered by the Athenian Callippus (354 b.c.). Epistles VII and VIII, addressed to Dion’s partisans, belong to this time or were fabricated as belonging to it. They contain constructive advice which, in language and spirit, closely resembles Laws III. Plato died in 348/347 b.c., at the age of eighty.

Was Plato at all influenced in his later years by progress in the special sciences? It may be replied that later modifications in his general theory of knowledge seem to have been the product of his own reflection rather than of any remarkable discoveries and were not such as to affect his educational ideals. He did, however, absorb new scientific ideas and make use of them for his purposes as a moralist. This is seen in one way in the Timaeus, where the world is shown to be a product of beneficent rational design, and in another in the Laws, where theological consequences are drawn from the perfect regularity of the planetary movements.

In the Timaeus, Plato has not abandoned his theory of Forms, for Timaeus declares that the perpetually changing, visible cosmos can at best be an object of “right opinion.” The view earlier attributed to Socrates in Phaedo—that the only satisfactory explanation of physical facts is a teleological one—is assumed from the start and carried out in detail. Timaeus opposes mechanistic views with a superior atomism, in which Theaetetus’ construction of the mathematical solids plays a part. Sicilian influence is especially strong. From Empedocles“system the doctor Philistion of Locri, with whom Plato was personally acquainted,39 developed a theory whereby the heart is the center of life and consciousness, and the veins and arteries carry pneuma along with blood. Timaeus adopts this physiology and the explanation of disease which went with it, except that in making the brain the organ of consciousness he follows Alcmaeon. (It appears then to have been the Academy, with its Sicilian connections, which brought the knowledge of Empedoclean medicine to the mainland.) All this leads up to the conclusion that man can learn to regulate his life by study of the cosmos, which is a divine artifact but also an intelligent being.

The Athenian Stranger in the Laws says that he was no longer a young man when he became persuaded that each of the planets moves in a single path, and that we malign them when we call them “wanderers.” He evidently speaks for Plato, and the remark is a formal withdrawal of what was said in RepublicVII of the erratic celestial movements; but in favor of what new system? Surely that of Eudoxus. This may not have lasted long, and was open to an objection that was soon seen, but it was the first scientific astronomy. From it Plato could, and did, argue that all movement stems from a soul (matter is inactive); perfectly regular movement stems from a wise and beneficent soul; and the rotation of the stars, sun, and planets is perfectly regular.

In these later developments Plato may appear not as a lover of science but as a biased user of it. But “an intense belief that a knowledge of mathematical relations would prove the key to unlock the mysteries of the relatedness within Nature was ever at the back of Plato’s cosmological speculations” (Whitehead, Adventures of Ideas, p. 194).40


1. Proclus in his copoentary on Euclid’s Elements gives a summary account of the development of geometry from the time of Thales. He claims that Plato brought about a great advance, and names some of those who worked with his encouragement in the Academy. Closely similar language is used in a fragmentary papyrus found at Herculaneum, “Academicorum philosophorum index Herculanensis,” where Plato’s role is said to be that of a supervisor who propounded problems for investigation by mathematicians. Simplicius in his copoentary on Aristotle’s De Caelo informs us that Eudoxus’s astronomical system was a solution of a carefully formulated problem set by Plato. The common source of the first two reports is probably the history of mathematics by Eudemus of Rhodes, and Simplicius says that his statement is derived from Book 2 of Eudemus’ History of Astronomy. Greek texts are in K. Gaiser, “Testimonia Platonica” (Appendix to Platons Ungeschriebene Lehre), nos. 15–21, 460–479. An English translation of the latter part of the Proclus passage is in Heath, A Manual of Greek Mathematics, 184–185.

2.Apology 34a; RepublicII , 368a.

3.Memorabilia III, 6.

4. For a family tree, see John burnet, Greek Philosophy From Thales to Plato (London, 1924), appendix; or C. Ritter, Platon, I, 13.

5.Epistles VII, 324–326.

6.Apology 34a.

7.Ibid., 38b.

8.Phaedo 59b, c.

9. Diogenes Laertius III , 6, and II , 106, quoting Hermodorus, a pupil of Plato.

10.Phaedo 78a, 107b.

11. W. and M. Kneale, The Development of Logic (Oxford, 1962), ch. 3; B. Mates, Stoic Logic (Berkeley-Los Angeles, 1961), intro.

12. Aelian, V, 16; VII 14; and Diogenes Laërtius, III, 8, where there is confusion between Plato and Socrates.

13. Robin, Platon, pp. 101–103.

14. Cornford, Republic of Plato, Intro., p. xvii.

15.EpistlesVII , 326–327.

16.De RepublicaI , 10.

17.Phaedo 61d.

18.De finibusV , 29.87.

19.Metaphysics, 987a32.

20.Phaedo 75E, 76e.

21.RepublicVI , 503–505.

22.RepublicVI , 484c, d.

23.LawsVII , 819–820.

24.RepublicVI , 510c.

25.Ibid., VII , 528b.

26.Ibid., 528e ff.

27.Ibid., 533.

28. Cornford, who gives this exposition, relies upon Parmenides 142D ff. See his trans. of the Republic, p. 245, and his “Mathematics and Dialectic in the Republic VI-VII.”

29.RepublicVII , 535–540.

30. See Cicero, De finibus V, 1, for an eloquent description of a walk to the gymnasium’s original site, now deserted.

31. Especially Nicomachean Ethics X, ch. 1.

32.RepublicVII , 535–540.

33. Euclid XIII, 18A

34. See Cornford, “Mathematics and Dialectic in the RepublicVI–VII ,” pp. 68–73.

35.Quaestiones convivales 718f.

36.Metaphysics A, 992a20; see Ross ad. loc

37. See Stocks’s note in oxford trans. of Aristotle, vol. II ; and Guthrie’s ed. of Aristotle’s on the Heavens (Loeb), p. 205.

38. Aristotle, p. 18 and elsewhere.

39.Epistles II, 314d.

40. That the system presented through Timaeus is formulated in antithesis to mechanist atomism—whether or not Plato knew of Democritus as its chief author—is clearly shown by Frank, Platon u. die sogenannten Pythagoreer, pp. 97–108. On the meaning of Timaeus 40b, c, concerning the earth’s rotation, see Cornford, Plato’s Cosmology, pp. 120–134. On Philistion, see Jaeger, Diokles von Karystos, pp. 7, 211. For the argument that laws 822a–e can refer only to the system of Eudoxus, and for Plato’s astronomy in general, see Burkert, Weisheit und Wissenschaft, pp. 302–311.


I. Original Works. For present purposes the most important dialogues are Meno, Phaedo, Republic, Parmenides, Theaetetus, Timaeus, and Laws. The Epistles and Epinomis, even if they are not authentic, are informative. There are translations with introductions and notes in many modern languages.

Some useful English versions are Phaedo, R. Hackforth, trans. (Cambridge, 1955); Republic, F. M. Cornford, trans. (Oxford, 1941); Theaetetus, Parmenides, and Timaeus, F. M. Cornford, trans., in vols. entitled, respectively, Plato’s Theory of Knowledge (London, 1935), Plato and Parmenides (London-New York, 1939), and Plato’s Cosmology (London, 1937); Timaeus and Critias, A.E. Taylor, trans. (London, 1929); Philebus and Epinomis, A.E. Taylor, trans., R. Klibansky et al., eds. (Edinburgh-London, 1956), with intro. to the latter by A. C. Lloyd; Epinomis, J. Harward, trans. (Oxford, 1928); Epistles, J. Harward, trans. (Cambridge, 1932); Epistles, Glenn R. Morrow, trans. (Urbana, III., 1935; repr. New York 1961); Laws, A. E. Taylor, trans. (London, 1934; repr. 1960).

The appropriate vols. in the French trans., Oeuvres complètes, 13 vols. in 25 pts. (Paris, 1920–1956), published under the patronage of the Association Guillaume Budé, should also be consulted.

II. Secondary Literature. On Plato’s life, see H. Leisegang, Platon, in Pauly-Wissowa, Realenzyklopādie, 1st ser., XX. The following books and articles are important for his views concerning method and for an estimate of his understanding of science.

J. Adam, The Republic of Plato, II (Cambridge, 1902); W. Burkert, Weisheit und Wissenschaft (Nuremberg, 1962), containing a useful bibliography; F.M. Cornford, “Mathematics and Dialectic in the Republic VI–VII,” in Mind, 41 (1932), 37–52, 173–190, repr. in Studies in Plato’s Metaphysics, R. E. Allen, ed. (London, 1965), 61–95; and E. Frank, Platon und die sogenannten Pythagoreer (Halle, 1923).

See also K. Gaiser, Platons ungeschriebene Lehre, 2nd ed. (Stuttgart, 1968), which contains in an app. the Testimonia Platonica, ancient evidence relative to the organization of the Academy and to Plato’s esoteric teaching; and “Platons Menon und dic Akademie,” in Archiv für Geschichte der philosophie, 46 (1964), 241–292; T. L. Health, History of Greek Mathematics (Oxford, 1921), and Aristarchus of Samos (Oxford, 1913), esp. chs. XV and XVI ;G. E. R. Lloyd. “Plato as Natural Scientist,” inJournal of Hellenic Studies, n 88 919680, 78–92; C. Ritter, Platon, 2 vols. (Munich, 1910–1922), containing a chapter on plato’s doctrine of nature and his attitude toward the problems of science; L. Robin, platon (paris 1935); F. Solmsen, “Platonic Influences in the Formation of Aristotle and Plato in the Mid-Fourth Century Goteborg,1960);and A. E. Taylor, Plato, the Man and His Work, 4th ed. (London,1937).

There is a review of literature relating to plato, 1950–1957, by H. Cherniss in Lustrum, 4 (1959),5–308, and 5 (1960), 323–648; sec. II.B deals with the Academy, sec. V.E with mathematics and the sciences.

On the Academy, the comprehensive account in E. Zeller, Philosophie der Griechen, 6th ed. (Hildesheim, 1963), has not yet been superseded; and H. Usener, “Organisation der wissenchaftlichen Arbeit,” in Preussische Jahrbucher, 53 (1884), repr. in Vortrage und Aufsätze (1907), 67 ff., has been a starting point for later discussion. See also E. Berti, La filosofia del primo Aristotele (Padua, 1962), pp. 138–159; H. Cherniss, The Riddle of the Academy (Berkeley, 1945); H. Herter, platons Akademie, 2nd ed. (Bonn, 1952); W. Jaeger, Aristole, 2nd ed. (Oxford, 1948), Diokles von Karystos (Berlin, 1938), and Paideia (Oxford, 1944), II and III; G. Ryle, Plato’s Progress (Cambridge, 1966); P.M. Schuhl, “Une école de sciences politiques,” inRevue Philosophique de la France et de L’étranger, 84 (1959), 101–013; J. Stenzel, platon der Erzieher (Leipzig, 1928); and U. von Wilamowitz, platon (Berlin, 1919; 5th ed. 1959).

On Eudoxus, se K. von Fritz, “Die Lebenszeit des Eudoxos v. Knidos,” in philologus, 85 (1929–1930), 478–481; H. Karpp, Die philosophie des Eudoxos v. Knidos (Wurzburg, 1933); and E. Frank, “die Begründung der mathematischen Naturwissenschaft durch Eudoxus?” in L. Edelstein, ed., Wissen, Wollen, Glauben (Zurich, 1955),134–157.

On the mathematical intermediates in Plato’s philosophy, see W. D. Ross, Metaphysics of Aristotle (Oxford, 1924), I, 166 ff.; J. A. Brentlinger, “The Divided Line and Plato’s Theory of Intermediates,” in phronesis, 7, no. 2 (1963) 146–166; S. Mansion, “L’objet des mathematiques et de la dialectique selon platon,” in Reuue philosophique de Louvain, 67 (1969), 365–358.

On the number in RepublicVIII , 546, see The Republic of Plato, Adam. ed., II, 201–203, 264–312; A. Diès, “Le Nombre de platon,” in Mémoires de l’Académie des inscriptions, 14 (1940); Gasier, Platons ungeschribene Lehre, pp. 271–273,409–414. On the shape of the earth in the Phaedo, see Burkert, Weisheit und Wissenschaft, pp. 282–284, and earlier literature there mentioned. On Platon as geographer and as physicist, see P. Friedländer, Platon, 2nd ed. (Berlin,1954), I, chs. 14, 15. On the Epinomis and the history of science, see E, des Places, “Notice” to the Epinomis, in Platon, Oeuvres completes, Collection Bude, XII, 118–128.

D. J. Allan

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Plato, son of Ariston, a member of the Athenian nobility, was born in 427 B.C. and died at the age of eighty in 347 B.C. Perhaps the greatest thinker of all times, he was not only a philosopher but the founder of political theory (he was himself involved in practical politics) and of sociology; he was, moreover, a physicist and a cosmologist. His influence, direct as well as indirect, upon European (and thus American) thought is incalculable. Whether his influence was on the whole beneficial or not is a question which has recently become highly controversial. For his political philosophy is authoritarian and hostile to democratic ideas, as when he said, “The wise shall lead and rule, and the ignorant shall follow” (Laws 690b), just as his social theory is collectivistic and hostile to individualistic ideas: “You are created for the sake of the whole, and not the whole for the sake of you” (Laws 903c). He identified individualism with egoism and group egoism with altruism, overlooking the fact that people may be unselfish not only for the sake of “the whole” (the collective, the state) but also for the sake of other individuals.

Plato’s deep interest in the problems of politics and of society seems to have had two roots. One was a family tradition of assuming political responsibilities. (His father claimed descent from Codrus, the last king of Athens, and his mother from Dropides, a kinsman of Solon.) The other was the terrifying experience of the political and social disintegration which affected not only Athens but the whole of the Greek world during the later years of the Peloponnesian War (the “Decelean war” of 419–404 b.c.). This period coincided with Plato’s formative years and culminated for him in the trial and death of his friend and teacher Socrates in 399 b.c.

The Peloponnesian War (or wars; 431–404 b.c.) was not merely a war between the two most powerful city-states of Greece; it became, one might say, the first ideological war, and it involved some of the first large-scale ideological persecutions. The clash was between the ideologies of a tribalist and authoritarian (and perhaps even totalitarian) Sparta and the maritime trading empire of democratic Athens (the “Delian League”). It became the more terrible because some of the leading families of Athens and its democratic allies were traditionally antidemocratic and oligarchic, and sympathetic to Sparta. (Thus Aristotle mentioned in his Politics, 1310a, an oligarchic oath which even in his time was still in vogue, as he said; it consisted of the formula “I promise to be an enemy of the people, and to try my best to give them bad advice.”)

When the Spartan King Lysistratus captured Athens in 404, he instituted there an oligarchic puppet government, under Spartan protection, known as the Thirty Tyrants. The Thirty were led by two of Plato’s maternal uncles, the highly gifted Critias and the much younger Charmides. During the eight months of their reign of terror, the Thirty killed scores of Athenian citizens—almost a greater number of Athenians than the Spartan armies had killed during the last ten years of the war (Meyer [1884–1902] 1953–1958, vol. 5, p. 34). But in 403, when Plato was 24 years old, Critias and the Spartan garrison were attacked and defeated by the returning democrats. Originally only 70 men, led by Thrasybulus and Anytus, the democrats established themselves first in the Piraeus, where Plato’s uncles were killed in battle. For a time, their oligarchic followers continued the reign of terror in the city of Athens itself, but their forces were in a state of confusion and dissolution. Having proved themselves incapable of ruling, they were ultimately abandoned by their Spartan protectors, who concluded a treaty with the democrats. The peace treaty re-established democracy in Athens. Thus the democratic form of government had proved its superior strength under the most severe trials, and even its enemies began after a few years to think it invincible.

As soon as the restored democracy had re-established normal legal conditions, a case was brought against Socrates for “corrupting the youth”; its meaning was clear enough: he was accused of having corrupted Alcibiades, Critias, and Charmides, who were thought responsible for the defeat of Athens and for the bloody regime of the Thirty. In his defense Socrates insisted that he had no sympathy with the policy of the Thirty and that he had risked his life defying their attempt to implicate him in one of their crimes. He also made it clear that he preferred death to being prevented from speaking his mind freely to the young. Found guilty, he became the first martyr for the right of free speech.

Such were the tumultuous times of Plato’s most important formative years. They led him in his time of maturity to pose his fundamental problem: Society, and the body politic, are sick. How can they be cured?

Beginning of literary activity. That the historical events described influenced Plato in the sense indicated is, of course, conjectural. Indeed, it should be stressed that almost everything about the evolution of Plato’s thought, the sequence of his works, and the events of his life is conjectural. Our sources, so far as they are consistent, seem to be largely interdependent. Thus, we cannot be certain that this story of Plato’s life is not a legend. What is probably the oldest source, the Book of Plato’s Letters, may well be an ancient forgery. Even the most informative “Seventh Letter,” which many scholars accept as genuine, is suspect. (Certain other works transmitted under Plato’s name are almost certainly forgeries.) Yet even though the “Seventh Letter” is probably a forgery, it appears to be very old, and the writer must surely have been well informed about the facts of Plato’s life to get his forgery accepted. For the temporal order of Plato’s works, we have now what appears to be very good evidence from the statistics of minor stylistic peculiarities (“stylometry”). This method (which in the main leads to groupings rather than to a definite sequence) may fail, however, in cases in which Plato revised or rewrote his books. (We seem to have some independent evidence for the revision, by Plato, of at least one of his works, the Theaetetus; see Popper [1945] 1963, vol. 1, addendum II.) These uncertainties should be kept in mind throughout this account.

Most of Plato’s literary work consists of “Socratic dialogues”—dialogues, that is, in which Socrates is the main speaker and the superior intellect. Socratic dialogues were composed by several other writers, notably Xenophon; yet most of Plato’s dialogues bear the stamp of supreme originality, and we may therefore conjecture that it was Plato who invented this literary form. If so, then the view expressed by some scholars that it was the tragic death of Socrates which turned Plato into an author —into a writer of Socratic dialogues, to commemorate (and defend) his friend and teacher—is not only attractive but also likely to be true. This view would also suggest that the Apology of Socrates— Plato’s report of Socrates’ defense and of his condemnation—was Plato’s first work. Admittedly, there is important evidence against this: the Apology is a masterwork, and quite a number of the early dialogues are, in comparison, immature. On the other hand, it is not so very unusual that an author’s first work shows him at a peak which he is not soon to reach again; and in this particular case, the unique personality of Socrates and the immediate impression made by his defense in court (Plato made it quite clear that he was present) may be more than sufficient to explain how one of the greatest and most moving works of all literature could be the first fruits of a literary novice.

At at any rate, until we have good evidence to the contrary, it seems reasonable to accept the Apology as a true portrait of the historical Socrates and as a faithful report of the proceedings (hundreds of eyewitnesses of these proceedings must have been alive when the Apology was first published). It is a marvelous portrait, and the first (or almost the first, in view of Xenophanes and Pericles and Euripides) and the greatest manifesto of what may be called “critical rationalism”—the characteristically Socratic view that we ought to be aware of how little we know, and that we can learn by means of those critical discussions to which all theories and beliefs ought to be made subject. Though this is hardly a view which could ever become a generally accepted one, its influence upon Western thought (and Western science) has been of decisive importance.

Socrates’ critical rationalism is not skeptical, nor does it take pride in reason or cleverness: he believes in truth and in human beings, of whose intrinsic fallibility and intrinsic goodness he is equally convinced. Moreover, he is loyal to the democratic laws of Athens, and he loathes the crimes of the Thirty: he is a democrat, though one who is not greatly impressed by the democratic party leaders; he is a man passionately interested in other men; he is ready to die for the right of free discussion but despises the art of flattering the people.

Three periods of Platonic works. It is here proposed to divide Plato’s work into three periods. The first, or Socratic, period develops Plato’s portrait of Socrates as a man, teacher, and lover of truth. Its dialogues (I mention only the Crito, the Protagoras, and the Meno) are opposed neither to democracy nor to the value of the individual.

In the second period, Plato’s attitude, imputed to the Socrates of his dialogues, is different: Plato now blames democratic Athens—nay, democracy itself, the rule of the many, of the mob—for having murdered Socrates. This mob rule threatens every just man, who is like “a man who has fallen among wild beasts, unwilling to share their misdeeds and unable to hold out singly against the savagery of all” (Republic 496c).

This shows that the social body is sick. Plato has found his problem: how to heal the sick body of society.

The problem itself involves a theory—the organic theory of the state and of society. (The origin of this most dubious and ever-influential theory is Oriental.)

Plato’s new and very personal version of the organic theory of society is his analogy between the city-state and the soul of man: the city-state is the soul writ large, and the soul is a state in miniature. He thus originated the psychological theory of the state and also the political theory of the soul. The state is class-divided. Its structure is characterized by an unstable equilibrium between the ruling classes, consisting of the rulers and their helpers (or auxiliaries), and the ruled classes, the money-earning classes and the slaves. Similarly, the structure of the soul is characterized by an unstable equilibrium—indeed a schism—between its upper functions, reason and will, and its lower functions, the instincts or appetites. (It is interesting to note that Marx and Freud were unconscious Platonists. They also were anti-Platonists in accepting Plato’s scheme and inverting it, Marx by demanding the emancipation of the workers, Freud by demanding the emancipation of the instincts or appetites.)

The challenge of his problem led Plato to an almost superhuman intellectual effort. He developed not only a diagnosis and a therapy but (especially in his third period) a whole cosmology on which he based his diagnosis, and a theory of knowledge on which he based his therapy.

His social diagnosis goes deep. He is not satisfied with blaming democracy, which for him is a symptom rather than the malady itself. For the malady is social revolution—the revolutionary change which has overcome society and which has led to the dissolution of the old patriarchal society in which everybody knew his place and was happy. Society is in a process of degeneration: change is evil; stability is divine.

The stages of political degeneration are seen by Plato in the history of the Greek city-states. They begin with a golden age of hereditary kingship— the rule of the one, the best, the wisest—and an organic division of labor: the wisest rule, the courageous help them to keep order and defend the state, and the people work (in a variety of occupations). From here we move through aristocracy (or timarchy), the rule of the few who are the best, to the rule of the many, democracy. In the Republic, democracy is shown to lead only too easily to a final state of decay: to the rule of the ruthless demagogue who makes himself the tyrant of the city.

What are the causes of political degeneration? According to the Republic, the main work of Plato’s second period, it is the racial degeneration of the ruling class which undermines its fitness and its determination to rule. According to the Laws, the main work of his third period, the main cause of social change is culture clash, which is an unavoidable concomitant of the development of industry (such as the Athenian silver mines), of trade, of possessing a harbor and a fleet, and of founding colonies. All this shows astonishing insight, as does the remark that population pressure is one of the main causes of an unsettled society. (It seems not unlikely that Plato connected population increase, or increase in quantity, with racial degeneration, or decrease in quality: his view of the few who are good and the many who are bad may have suggested this to him (Laws 710d, 740d-741a, 838e).

So much for Plato’s sociological diagnosis.

The therapy which Plato advocated—his political program—fits the diagnosis: Arrest all social change! Return (so far as this is possible) to the patriarchic state! Strengthen the stability and the power of the ruling class, its unity, and its will to rule! For Plato formulated the following diagnostic-sociological law of revolution: “Change in the constitution originates, without exception, in the ruling class itself, and only when this class becomes the seat of dissension,” or when its will to rule is sapped, or when it is defeated in war (Republic 545d, 465b). Thus, the proper education of the ruling class becomes a major instrument of politics; the degeneration of the ruling class must be prevented by eugenics; the unity of the ruling class must be strengthened by a radical communism (confined to the ruling class) that involves the common ownership of women and children: nobody may know who his actual parents are, and everybody must look upon all the members of the older generation of their class as their parents. (This startling communism is the only major point of Plato’s program given up in the Laws as demanding too much, even though it is still declared to be ideally the best form of society.) Culture clash must be prevented, and it is said in the Laws that the city must therefore possess no harbor and no fleet, and that no citizen may possess means for traveling: the currency must be a token currency without intrinsic value (Laws 742a-c), though the government will possess a treasure of “general Hellenic currency.” Religion and rites are to be developed as important instruments for preventing change, and no variation in them may be tolerated. (This view, which anticipates the idea that religion is opium for the people, is the more remarkable for the absence of any churchlike organization in Greece.)

In his third period (especially in the Laws) Plato no longer used Socrates as his main speaker: it seems that he had become conscious that he had moved far away from Socrates’ teaching. Plato developed the political ideas of his middle period further and gave them (especially in the Statesman and the Timaeus) a cosmological background: the deepest cause of racial degeneration and political decay is that we are living in a world period in which the world is moving away from its divine origin; every change makes it less like its original model—the divine Form, or Idea, in whose image it was created.

In this third period, Plato developed further his theory of knowledge. In his first period, it was an optimistic theory which made it possible for every man to learn (Meno 81b–d). In his second and third periods, only the highly trained philosopher can attain true knowledge—knowledge of the divine Forms or Ideas.

Later life. It is difficult to relate the works of Plato’s second and third periods to his later life, whose most important events, according to tradition, were his journeys (one to Egypt and three to Syracuse), the foundation of the Academy, and the Academy’s (and Plato’s) participation in Syracusan high politics: his friend Dio invaded Syracuse, supported by other members of the Academy, and overthrew the Dionysian dynasty. Dio was murdered by Callipus, another member of the Academy, who in turn was murdered by the Pythagorean philosopher Leptines. (At least nine pupils of Plato’s Academy made themselves tyrants of some city or other.)

Traces of these journeys, such as allusions to Egyptian institutions, and of some others of these events, may be discerned in Plato’s work, but most of these interpretations, though interesting, are highly controversial.

The influence (for good or ill) of Plato’s work is immeasurable. Western thought, one might say, has been either Platonic or anti-Platonic, but hardly ever non-Platonic.

Karl R. Popper

[See alsoConstitutions and constitutionalism; Elites; Justice natural law; Political theory; Social contract; State; Utopianism, article onutopias and utopianism; and the biography ofAristotle.]


Plato. With an English translation. 10 vols. The Loeb Classical Library. London: Heinemann; New York: Putnam, 1917–1929. → Volume 1: Euthyphro; Apology; Crito; Phaedo; Phaedrus, 1917. Volume 2: Theaetetus; Sophist, 1921. Volume 3: The Statesman; Philebus; Ion, 1925. Volume 4: Laches; Protagoras; Meno; Euthydemus, 1924. Volume 5: Lysis; Symposium; Gorgias, 1925. Volume 6: Cratylus; Parmenides; Greater Hippias; Lesser Hippias, 1926. Volume 7: Timaeus; Critias; Cleitophon; Menexenus; Epistles, 1929. Volume 8: Charmides; Alcibiades I and II; Hipparchus; The Lovers; The Ages; Minos; Epinomis, 1927. Volumes 9–10: The Laws, 1926.

The Republic. With an English translation by Paul Shorey. 2 vols. The Loeb Classical Library. London: Heinemann; New York: Putnam, 1930–1935.


AristotlePolitics. With an English translation. London: Heinemann; Cambridge, Mass.: Harvard Univ. Press, 1959.

Bluck, Richard S. H. (1949) 1951 Plato’s Life andThought. Boston: Beacon.

Burnet, John 1928 Platonism. Berkeley: Univ. of California Press.

Cherniss, Harold F. (1945) 1962 The Riddle of the Early Academy. New York: Russell.

Cherniss, Harold F. 1959–1960 Plato (1950–1957). 2 parts. Lustrum, Nos. 4–5. Göttingen: Vandenhoeck & Ruprecht.

Chroust, Anton-Herman 1962 Plato’s Detractors in Antiquity Review of Metaphysics 16:98–118.

Crossman, R. H. S. (1937) 1959 Plato Today. 2d ed. London: Allen & Unwin; New York: Oxford Univ. Press.

Demos, Raphael 1939 The Philosophy of Plato. New York and London: Scribner.

Dodds, Eric R. 1951 The Greeks and the Irrational. Berkeley: Univ. of California Press. → A paperback edition was published in 1963.

Field, Guy C. 1930 Plato and His Contemporaries: A Study in Fourth-century Life and Thought. London: Methuen.

Fite, Warner 1934 The Platonic Legend. New York and London: Scribner.

FriedlÅnder, Paul (1928–1930) 1958–1964 Plato. 2 vols. New York: Pantheon.

Gomperz, Theodor (1896–1909)1955 Greek Thinkers: A History of Ancient Philosophy. 4 vols. New York: Humanities Press. → First published in German. See especially volumes 2 and 3.

Grote, George (1865) 1888 Plato, and the Other Companions of Sokrates. 2d ed. 4 vols. London: Murray.

Kelsen, Hans 1942 Platonic Love. American Imago 3:3–110.

Kelsen, Hans 1957 What Is Justice? Berkeley and Los Angeles: Univ. of California Press. → See especially pages 82–109, “Platonic Justice.”

KoyrÉ, Alexandre 1945 Discovering Plato. New York: Columbia Univ. Press. → A paperback edition was published in 1960.

Levinson, Ronald B. 1953 In Defense of Plato. Cambridge, Mass.: Harvard Univ. Press.

Lodge, Rupert C. 1956 The Philosophy of Plato. London: Routledge.

Meyer, Eduard (1884–1902) 1953–1958 Geschichte des Altertums. 4th ed. 5 vols. Stuttgart (Germany): Cotta.

Morrow, Glenn R. 1939a Plato and Greek Slavery. Mind New Series 48:186–201.

Morrow, Glenn R. 1939b Plato’s Law of Slavery in Its Relation to Greek Law. Urbana: Univ. of Illinois Press.

Morrow, Glenn R. 1960 Plato’s Cretan City: A Historical Interpretation of The Laws. Princeton Univ. Press.

Popper, Karl R. (1945) 1963 The Open Society and Its Enemies. 4th rev. & enl. ed. 2 vols. Princeton Univ. Press. → Volume 1: The Spell of Plato. Volume 2: The High Tide of Prophecy: Hegel, Marx and the Aftermath.

Popper, Karl R. (1960) 1963 On the Sources of Knowledge and of Ignorance. Pages 3–30 in Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge. New York: Basic Books; London: Routledge.

Ross, W. David (1951) 1961 Plato’s Theory of Ideas. Oxford: Clarendon.

Ryle, Gilbert 1966 Plato’s Progress. Cambridge Univ. Press

Sabine, George H. (1937) 1962 A History of Political Theory. 3d ed. New York: Holt.

Shorey, Paul 1903 The Unity of Plato’s Thought. Univ of Chicago Press.

Shorey, Paul 1933 What Plato Said. Univ. of Chicago Press

Taylor, Alfred E. (1926) 1960 Plato: The Man and His Work. 7th ed. London: Methuen.

Von Fritz, Kurt 1954 The Theory of the Mixed Constitution in Antiquity: A Critical Analysis of Polybius’ Political Ideas. New York: Columbia Univ. Press.

Wild, John D. (1953) 1959 Plato’s Modern Enemies and the Theory of Natural Law. Univ. of Chicago Press.

Winspear, Alban D. (1940) 1956 The Genesis of Plato’s Thought. 2d ed. New York: Russell.

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Plato (427?–347 B.C.E.)

PLATO (427?347 B.C.E.)

Plato (427?347 b.c.e.) was a prominent Athenian philosopher who posed fundamental questions about education, human nature, and justice.

A student of the famous philosopher Socrates, Plato left Athens upon his mentor's death in 399 b.c.e. After traveling to other parts of Greece, Italy, and Sicily, Plato returned to Athens in 387 b.c.e. and founded a school of mathematics and philosophy called the Academy, which became the most prominent intellectual institution in all of ancient Greece. Plato authored a number of dialogues that often depicted Socrates engaging in the educational mode of dialectic. Like his mentor, Plato suspected that most people did not know what they claimed to know, and hence wondered why rigorous qualifications for rulers did not exist. Challenging the Sophists' claims that knowledge and truth were relative to the perspective of each individual, Plato developed an epistemology and metaphysics that suggested an absolute truth that could only be gleaned through rigorous self-examination and the development of reasonskills crucial for enlightened political leaders.

The Ideal State

Plato's educational ideas derived in part from his conception of justice, both for individuals and for the ideal state. He viewed individuals as mutually dependent for their survival and well-being, and he proposed that justice in the ideal state was congruent with justice in the individual's soul.

Plato's ideal state was a republic with three categories of citizens: artisans, auxiliaries, and philosopher-kings, each of whom possessed distinct natures and capacities. Those proclivities, moreover, reflected a particular combination of elements within one's tripartite soul, composed of appetite, spirit, and reason. Artisans, for example, were dominated by their appetites or desires, and therefore destined to produce material goods. Auxiliaries, a class of guardians, were ruled by spirit in their souls and possessed the courage necessary to protect the state from invasion. Philosopher-kings, the leaders of the ideal state, had souls in which reason reigned over spirit and appetite, and as a result possessed the foresight and knowledge to rule wisely. In Plato's view, these rulers were not merely elite intellectuals, but moral leaders. In the just state, each class of citizen had a distinct duty to remain faithful to its determined nature and engage solely in its destined occupation. The proper management of one's soul would yield immediate happiness and well-being, and specific educational methods would cultivate this brand of spiritual and civic harmony.

The Dialectical Method

Plato's educational priorities also reflected his distinct pedagogy. Challenging the Sophistswho prized rhetoric, believed in ethical and epistemological relativism, and claimed to teach "excellence"Plato argued that training in "excellence" was meaningless without content and that knowledge was absolute, certain, and good. As a result, teachers assumed a high moral responsibility. Plato doubted whether a standard method of teaching existed for all subjects, and he argued that morally neutral education would corrupt most citizens. He preferred the dialectical method over the Sophists' rhetorical pedagogy. For Plato, the role of the teacher was not to fill an empty reservoir with specific skills, but to encourage the student to redirect his or her soul and to rearrange the priorities within it to allow reason to rule over the irrational elements of spirit and appetite.

In the Meno, Plato examined a paradox that challenged the dialectical method of education: if one knows nothing, then how will one come to recognize knowledge when he encounters it? In response, Plato's Socrates proposed a different idea. Through a geometry lesson with a slave boy, he attempted to demonstrate that all possessed some minimal knowledge that served as a window into one's eternal and omniscient soul. Through dialectic, the teacher could refute the student's false opinions until the student pursued a true opinion that survived the rigors of critical examination. Unacquainted with the storehouse of knowledge in one's soul, a person needed to learn how to access or "recollect" it. Plato distanced himself further from the Sophists by distinguishing knowledge (eternal and certain) from opinion (unreliable and ephemeral).

Plato developed this idea more fully in the Republic, declaring knowledge superior to opinion in both an epistemological and ontological sense. Opinion reflected a misapprehension of reality, while knowledge belonged to an essential or "intelligible" realm. In particular, Plato proposed a linear hierarchy of knowledge starting with the "visible" realms of imagination and then belief, and moving to the "intelligible" realms of reason, and ultimately, knowledge. In his celebrated cave metaphor, Plato's Socrates depicted chained prisoners, who presumed shadows of representations cast by artificial light to be real. The first step of education, then, was to turn one's soul away from this artificial world of shadows and toward the representations of objects and ideas themselvesleading one to the realm of belief. The objects of belief, however, were still empirical, and thus, ephemeral, relative, and unreliable. Beyond the cave lay the intelligible realm of reason and knowledge. Plato asserted that ideas did not possess any physical qualities, and to ascend beyond the world of tangible objects and ideas, one needed to develop the power of abstract thinking through the use of postulates to draw conclusions about the universal essence or "form" of an object or idea. Mathematics constituted a particularly useful tool for the development of reason, as it relied heavily on logic and abstract thought. The ultimate stage of awareness for Plato was knowledge of the "form of the good"a transcendence of all postulates and assumptions through abstract reasoning that yielded a certain and comprehensive understanding of all things.

Educational Programs

Plato also made clear that not all citizens of the ideal state possessed the same capacity to realize the "form of the good." As a result, he proposed distinct educational programs for future artisans, auxiliaries, and philosopher-kings. Plato favored mathematics as a precise and abstract model for the development of thought in the future rulers of the just state. Knowledge, however, could only be attained through the use of dialectic to shed all assumptions and to glean the first principle of all, the "form of the good." After many years of mathematical and dialectical study, followed by fifteen years of public service, the best of this group would have come to understand the "form of the good" and have become philosopher-kings. Cognizant of the interrelationship of all things and confident of the reasons behind them, the intellectually and morally elite would be equipped to rule the just state in an enlightened manner.

The Cultivation of Morals

In addition, Plato advocated the removal of all infants from their natural families to receive a proper aesthetic educationliterary, musical, and physicalfor the development of character in the soul and the cultivation of morals necessary for sustaining the just state. Suspecting that most writers and musicians did not know the subjects they depictedthat they cast mere shadows of representations of real objects, ideas, and peoplePlato feared that artistic works could endanger the health of the just state. Consequently, he wanted to hold artists and potential leaders accountable for the consequences of their creations and policies. This is why Plato advocated the censorship of all forms of art that did not accurately depict the good in behavior. Art, as a powerful medium that threatened the harmony of the soul, was best suited for philosophers who had developed the capacity to know and could resist its dangerous and irrational allures. Exposure to the right kinds of stories and music, although not sufficient to make a citizen beautiful and good, would contribute to the proper development of the elements within one's soul. For Plato, aesthetics and morality were inextricable; the value of a work of art hinged on its propensity to lead to moral development and behavior.

A Less-Ideal State

In the Laws, Plato considered the possibility that not only the majority, but all citizens could be incapable of reaching the "form of the good." He thus envisioned a second-best state with rulers ignorant of the "form of the good" but capable of thought. Such a society had absolute and unyielding rulers who eradicated any idea or thing that questioned their authority. Acting as if they possessed wisdom, such leaders established laws that reflected their opinions and their imperfect conception of the good.

Modern Scholarship

Contemporary advocates of popular democracy have criticized Plato's republican scheme as elitist and tyrannical in prizing order over individual liberty. Indeed, Plato believed that individuals could not stand alone, and as most would never reach internal harmony or virtue, the majority needed to be told how to conduct its life by those who possessed that knowledge. Incapable of understanding the reasons behind the laws, most citizens needed merely to obey them.

Some scholars have also questioned Plato's treatment of women in his just state. For instance, Jane Roland Martin has argued that although he did not differentiate education or societal roles on the basis of sex, Plato was not committed to gender equality. Despite his abolition of the family, gender distinctions would have likely persisted, as Plato did not seek to ensure the equal portrayal of men and women in literature. According to this view, Plato's female guardians-in-training warranted a distinct education from men to help mitigate the cultural, symbolic, and epistemological assumptions of female subordination. Identical education, then, did not necessarily constitute equal education, a point that holds significant implications for contemporary assumptions about the effects of coeducation.

These criticisms illustrate the longevity of Plato's educational, metaphysical, and ethical ideas. In addition, other scholars have eschewed the tendency to evaluate the modern implications of Plato's specific educational doctrines, and instead have highlighted his assumption that education could address fundamental social problems. They view Plato's method of inquirycritical self-examination through the dialectical interplay of teacher and studentas his primary contribution to educational thought. Indeed, perhaps education itself embodied the highest virtue of Plato's just state.

See also: Philosophy of Education.


Barrow, Robin. 1976. Plato and Education. London: Routledge and Kegan Paul.

Blankenship, J. David. 1996. "Education and the Arts in Plato's Republic. " Journal of Education 178:6798.

Martin, Jane Roland. 1985. Reclaiming a Conversation: The Ideal of the Educated Woman. New Haven, CT: Yale University Press.

Parry, Richard D. 1996. "Morality and Happiness: Book IV of Plato's Republic. " Journal of Education 178:3147.

Plato. 1976. Meno, trans. G. M. A. Grube. Indianapolis, IN: Hackett.

Plato. 1976. Protagoras, trans. C. C. W. Taylor. Oxford: Clarendon Press.

Plato. 1980. The Laws of Plato, trans. Thomas L. Pangle. New York: Basic Books.

Plato. 1992. Republic, trans. G. M. A. Grube and rev. C. D. C. Reeve. Indianapolis, IN: Hackett.

Scolnicov, Samuel. 1988. Plato's Metaphysics of Education. London and New York: Routledge.

Sevan G. Terzian

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In his written dialogues, Plato developed accounts of knowledge, reality, humanity, society, goodness, God, and beauty. Usually, when people speak of Platonism, they are referring to his theory of Forms, accompanied by a doctrine of the immortality of the soul and values that transcend power, prestige, and pleasure. Western thought has developed either by following and adapting his accounts or by reacting to them, either directly or indirectly through, most notably, Aristotle, Plotinus, Philo, and Augustine. The theory of Forms established the most basic concept of science as it came to be practiced in Europe, namely, that science aims to discover objective principles, in other words, "Forms." Plato's doctrine of the immortality of the soul and values that transcend the material world have reinforced and shaped systematic thinking within Judaism, Christianity, and Islam.

Life and times

Plato (428347 b.c.e.) was born in Athens to a rich and politically powerful family. Instead of taking his place in the ruling class, he became a philosopher. He founded the Academy and invented a new form of literature, the dramatic dialogue. His dialogues, featuring the philosopher Socrates (469399 b.c.e.), have profoundly shaped history, in a way comparable to the writings of Paul about Jesus.

Plato chose philosophy because he fell under the spell of Socrates as a young man while witnessing the horrors of political life in his time and city. At the time of Plato's birth, Athens, a city-state in Greece, was the world's first democracy, inventing such wonders as trial by jury, as well as some of the greatest sculpture, architecture, and drama of any age. But during this time of extraordinary human achievement, the wisest man of all, as confirmed by a religious oracle, was one who professed to have no wisdom at all: Socrates. Socrates would closely question people who professed to know politics, religion, or any deep wisdom about life, and he would show that their pretenses to wisdom were false. Socrates would also use his chains of questions to lead anyone who would speak with him to agree human excellence was exclusively a matter of wisdom, and that the search for wisdom was the best way to spend one's life.

Plato was fascinated by Socrates and joined other young men in spending time in his company. At the same time Plato observed how demagogues led Athens to prolong its Peloponnesian War (431404 b.c.e.) against Sparta, a war that ended in utter defeat for Athens. The Spartans installed an antidemocratic government that included members of Plato's family. This government ruled murderously, but briefly, until a citizens' armed rebellion restored the democracy, although Athens's empire and military preeminence were gone forever. Under this same democracy, just a couple of years later (399 b.c.e.), a religiously conservative prosecutor brought Socrates to trial on charges of atheism, heresy, and corrupting the young. The jury found Socrates guilty and sentenced him to death. It is no wonder that Plato became disillusioned with a life aimed at political rule, and decided instead to devote his life to developing Socrates's ideas.

Plato spent his time in private conversations with friends about Socrates' ideas, honoring his memory by continuing to seek wisdom. Some of these friends were Pythagoreans. Pythagoras lived about a hundred years before Plato in Greek colonies in the south of Italy. According to reports, Pythagoras had supernatural powers and formed a religious school of followers. He believed that human souls are reincarnated in animal and human bodies. Pythagoras also was aware of the mathematical structure of musical harmony and believed that numbers provide the explanation of all the order in the universe. Plato traveled to southern Italy a couple of times in his life, at least in part because of his interest in Pythagoras. In his written dialogues, Plato developed Pythagorean as well as Socratic ideas. Plato also followed Pythagoras in forming a school, which became known as the Academy.


Next to nothing is known of the way the Academy was run, but a great deal is known about Plato's writings, since all of his dialogues have survived. The dialogues present at least three different theoretical systems, probably from Plato's early, middle, and late periods, though any such dating is speculative and controversial. The early dialogues focus on ethical issues, and usually end with the speakers admitting their ignorance. For example, in the Laches the question is "What is courage?" in the Euthyphro "What is reverence?" in the Charmides "What is moderation?" in the Lysis "What is a friend?" and in the Protagoras "How are the virtues alike?" Though the arguments are inconclusive, they give an account of virtue as purely a matter of intellect, which is contrary to the widespread belief, then and now, that virtue requires proper desires or a good will in addition to technical know-how.

The middle and late dialogues end with the speakers reaching positive conclusions that are not limited to ethics. In the middle dialogues, such as the Phaedo, Symposium, Phaedrus, and Republic, Plato uses arguments to prove, as well as myths and metaphors to embellish, an account of the soul as having three parts: reason, which aims at truth; emotion, which seeks social values such as prestige; and desire, which aims at material satisfaction. This soul is immortal and destined to enjoy the beauty of divine objects that are not seen with the senses but understood, in much the way one understands mathematics with the intellect. It is the nature of these souls to be constantly reincarnated into various human and animal bodies. The process of reincarnation disorients the soul and makes it believe that sense objects are the only realities. Proper reflection on human crafts and sciences, as reflected in the use of language, enables human souls to recognize ultimate reality. The crucial turning point comes when one realizes that all well-made or beautiful or good objects share the same qualities or structure or Form. For example, it is not by sensory perception of particular beds that an expert carpenter or engineer designs and builds a bed, but by an intellectual recognition of what function beds are meant to perform. When the soul recognizes the reality of the Forms, and turns away from the senses towards such intellectual, math-like reasoning, it begins its path towards salvation. The soul achieves salvation by recognizing that the realm of Forms, not the material world, is true reality, so that one's desires for bodily and social goods cease to attach the soul to the material world, with the result that, at death, the soul is not drawn back into another body but ascends to the realm of the gods, if only for a limited time.

In the Timaeus, perhaps his most influential contribution to the dialogue between science and religion, Plato extends this account to general cosmology, explaining the design in the visible world by referring to a divine craftworker who fashioned the whole (by referring to Formal reality, of course) and insured its proper function by making it a living thing with a soul. Plato begins the tradition of perfect-being theology, which argues that God must be perfect, hence good, unchanging, eternal, and so on. In the later dialogues, beginning with the Parmenides, Plato raises problems with his theory of Forms, leading him not to abandon it but to abandon his middle period confidence that the Forms are simple enough that human minds can unmistakably know them without possibility of error.


Plato's influence on science and religion is probably greater than any other single person's. He lived at a time when there was no sharp distinction between the methods of religion and of science, and he was early enough in the history of western civilization to cast his shadow over the development of western science and religion. His influence on science is largely through Aristotle, who accepted with modifications Plato's view that the world can be explained in terms of form and matter and teleology, that is, the function objects are designed to perform. These categories dominated, and perhaps stifled, scientific thinking until the scientific revolution of the 1600s, when mathematical advances allowed scientists to try to explain the laws of nature in purely mechanistic terms (of particles pushing and pulling particles). Even in that revolution, Plato's influence continued. For instance, Galileo Galilei (15641642) used Plato's method of writing dialogues in the great debate between Ptolemaic and Copernican world systems to challenge the weight of religious authority by appeal to the light of reason.

Plato's influence on religion is even more profound. Philo (c. 20 b.c.e.c. 50 c.e.) attempted to explain Jewish religion in Platonist terms and set a model that would be followed by Christians. In the three centuries after the death of Jesus, Christians had to choose between different interpretations of their faith as found in their sacred writings. As they worked to establish a biblical canon and creeds, they found themselves engaging in discussions shaped by Plato's and Aristotle's metaphysical and theological ideas. Some of these early writers, such as Tertullian (c. 160c. 225), deplored any attempt to produce a platonic Christianity. Others, such as Origen (c. 185c. 254), used platonic reasoning to defend the faith in a manner that would be followed by Augustine of Hippo (354430), who in turn influenced all later Christian theology. Christian apologists appealed to platonic arguments to show that God exists and is perfectly good, that God designed the world, and that human beings have immortal souls. Then they supplemented these arguments with revelations from scripture. While critics of Christianity's Hellenization continue to this day, orthodox Christianity remains in the mold of perfect-being theology, and apologists continue to use platonic arguments.

See also Aristotle; Augustine; Christianity; Galileo Galilei; Idealism; Judaism; Soul; Teleology


burtt, edwin a. the metaphysical foundations of modern physical science. london: routledge and kegan paul, 1932.

cantor, norman f. the civilization of the middle ages. new york: harpercollins, 1993.

cooper, john m. plato: complete works. indianapolis, ind.: hackett, 1997.

copleston, frederick. a history of philosophy, vol. 1. new york: doubleday, 1962.

de santillana, giorgio. the origins of scientific thought. chicago: university of chicago press, 1961.

guthrie, w. k. c. a history of greek philosophy, vol. 5. cambridge, uk: cambridge university press, 1975.

hare, r. m. plato. oxford and new york: oxford university press, 1982.

irwin, terrence. classical thought. oxford and new york: oxford university press, 1989.

kenny, anthony, ed. the oxford history of western philosophy. oxford and new york: oxford university press, 1994.

livingstone, r. w. the legacy of greece. oxford: clarendon press, 1921.

lovejoy, arthur o. the great chain of being. cambridge, mass.: harvard university press, 1933.

nietmann, william f. the unmaking of god. lanham, md.: university press of america, 1994.

russell, bertrand. wisdom of the west. new york: crescent books, 1959.

tarnas, richard. the passion of the western mind. new york: harmony books, 1991.

george h. rudebusch

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The Greek philosopher Plato (428-347 B.C.) founded the Academy, one of the great philosophical schools of antiquity. His thought had enormous impact on the development of Western philosophy.

Plato was born in Athens, the son of Ariston and Perictione, both of Athenian aristocratic ancestry. He lived his whole life in Athens although he traveled to Sicily and southern Italy on several occasions, and one story says he traveled to Egypt. Little is known of his early years, but he was given the finest education Athens had to offer the scions of its noble families, and he devoted his considerable talents to politics and the writing of tragedy and other forms of poetry. His acquaintance with Socrates altered the course of his life. The compelling power which Socrates's methods and arguments had over the minds of the youth of Athens gripped Plato as firmly as it did so many others, and he became a close associate of Socrates.

The end of the Peloponnesian War (404 B.C.) left Plato in an irreconcilable position. His uncle, Critias, was the leader of the Thirty Tyrants who were installed in power by the victorious Spartans. One means of perpetuating themselves in power was to implicate as many Athenians as possible in their atrocious acts. Thus Socrates, as we learn in Plato's Apology, was ordered to arrest a man and bring him to Athens from Salamis for execution. When the great teacher refused, his life was in jeopardy, and he was probably saved only by the overthrow of the Thirty and the reestablishment of the democracy.

Plato was repelled by the aims and methods of the Thirty and welcomed the restoration of the democracy, but his mistrust of the whimsical demos was deepened some 4 years later when Socrates was tried on trumped up charges and sentenced to death. Plato was present at the trial, as we learn in the Apology, but was not present when the hemlock was administered to his master, although he describes the scene in vivid and touching detail in the Phaedo. He then turned in disgust from contemporary Athenian politics and never took an active part in government, although through friends he did try to influence the course of political life in the Sicilian city of Syracuse.

Plato and several of his friends withdrew from Athens for a short time after Socrates's death and remained with Euclides in Megara. His productive years were punctuated by three voyages to Sicily, and his literary output, all of which has survived, may conveniently be discussed within the framework of those voyages.

The first trip, to southern Italy and Syracuse, took place in 388-387 B.C., when Plato made the acquaintance of Archytas of Tarentum, the Pythagorean, and Dion of Syracuse and his infamous brother-in-law, Dionysius I, ruler of that city. Dionysius was then at the height of his power and prestige in Sicily for having freed the Greeks there from the threat of Carthaginian overlordship. Plato became better friends with Dion, however, and Dionysius's rather callous treatment of his Athenian guest may be ascribed to the jealously which that close friendship aroused. On Plato's return journey to Athens, Dionysius's crew deposited him on the island of Aegina, which at that time was engaged in a minor war with Athens, and Plato might have been sold as a prisoner of war had he not been ransomed by Anniceris of Cyrene, one of his many admirers.

His Dialogues

On his return to Athens, Plato began to teach in the Gymnasium Academe and soon afterward acquired property nearby and founded his famous Academy, which survived until the philosophical schools were closed by the Christian emperor Justinian in the early 6th century A.D. At the center of the Academy stood a shrine to the Muses, and at least one modern scholar suggests that the Academy may have been a type of religious brotherhood. Plato had begun to write the dialogues, which came to be the hallmark of his philosophical exposition, some years before the founding of the Academy. To this early period, before the first trip to Sicily, belong the Laches, Charmides, Euthyphro, Lysis, Protagoras, Hippias Minor, Ion, Hippias Major, Apology, Crito, and Gorgias. Socrates is the main character in these dialogues, and various abstractions are discussed and defined. The Laches deals with courage, Charmides with sophrosyne (common sense), Euthyphro with piety, Lysis with friendship, Protagoras with the teaching of arete (virtue), and so on. The Apology and Crito stand somewhat apart from the other works of this group in that they deal with historical events, Socrates's trial and the period between his conviction and execution. The unifying element in all of these works is the figure of Socrates and his rather negative function in revealing the fallacies in the conventional treatment of the topics discussed.

Plato's own great contributions begin to appear in the second group of writings, which date from the period between his first and second voyages to Sicily. To this second group belong the Meno, Cratylus, Euthydemus, Menexenus, Symposium, Phaedo, Republic, Phaedrus, Parmenides, and Theaetetus. Development of ideas in the earlier dialogues is discernible in these works. The Meno carries on the question of the teachability of virtue first dealt with in Protagoras and introduces the doctrine of anamnesis (recollection), which plays an important role in Plato's view of the human's ability to learn the truth. Since the soul is immortal and has at an earlier stage contemplated the Forms, or Ideas, which are the eternal and changeless truths of the universe, humans do not learn, but remember.

The impetus for learning or remembering the truth is revealed in the Symposium, where the ascent from corporeal reality to eternal and incorporeal truth is described. The scene is a dinner party at the house of the tragic poet Agathon, and each guest contributes a short speech on the god Eros. Socrates, however, cuts through the Sophistic arguments of his friends and praises Eros not as a separate and independent god but as an intermediary between gods and men. It is Eros who causes men to seek beauty, although for a time the unenlightened lover may think that what he is really seeking is the corporeal body of his beloved. Ultimately, however, one progresses from love of the body to love of the beauty which the body represents, and so forth, until one realizes that the ultimate goal sought is contemplation of beauty itself and of the Forms. The Forms are the true reality and impart their essence in some way to ephemeral, corporeal objects, and man may come to know this true reality through rigorous discipline of mind and body, and Plato went so far as to draw up a rough outline for a utopian state in his Republic.

The Republic

Socrates is again the main character in the Republic, although this work is less a dialogue than a long discussion by Socrates of justice and what it means to the individual and the city-state. The great utopian state is described only as an analogue to the soul in order to understand better how the soul might achieve the kind of balance and harmony necessary for the rational element to control it. Just as there are three elements to the soul, the rational, the less rational, and the impulsive irrational, so there are three classes in the state, the rulers, the guardians, and the workers. The rulers are not a hereditary clan or self-perpetuating upper class but are made up of those who have emerged from the population as a whole as the most gifted intellectually. The guardians serve society by keeping order and by handling the practical matters of government, including fighting wars, while the workers perform the labor necessary to keep the whole running smoothly. Thus the most rational elements of the city-state guide it and see that all in it are given an education commensurate with their abilities.

The wisdom, courage, and moderation cultivated by the rulers, guardians, and workers ideally produce the justice in society which those virtues produce in the individual soul when they are cultivated by the three elements of that soul. Only when the three work in harmony, with intelligence clearly in control, does the individual or state achieve the happiness and fulfillment of which it is capable. The Republic ends with the great myth of Er, in which the wanderings of the soul through births and rebirths are recounted. One may be freed from the cycle after a time through lives of greater and greater spiritual and intellectual purity.

Plato's second trip to Syracuse took place in 367 B.C. after the death of Dionysius I, but his and Dion's efforts to influence the development of Dionysius II along the lines laid down in the Republic for the philosopher-king did not succeed, and he returned to Athens.

Last Works

Plato's final group of works, written after 367, consists of the Sophist, the Statesman, Philebus, Timaeus, Critias, and the Laws. The Sophist, takes up the metaphysical question of being and not-being, while the Statesman concludes that the best type of city-state would be the one in which the expert is given absolute authority with no hindrance to his rule from laws or constitution. The Timaeus discusses the rationality inherent in the universe which confirms Plato's scheme, while the Laws, Plato's last work, once again takes up the question of the best framework in which society might function for the betterment of its citizens. Here great stress is laid on an almost mystical approach to the great truth of the rational universe.

Plato's third and final voyage to Syracuse was made some time before 357 B.C., and he was no more successful in his attempts to influence the young Dionysius than he had been earlier. Dion fared no better and was exiled by the young tyrant, and Plato was held in semicaptivity before being released. Plato's Seventh Letter, the only one in the collection of 13 considered accurate, perhaps even from the hand of Plato himself, recounts his role in the events surrounding the death of Dion, who in 357 B.C. entered Syracuse and overthrew Dionysius. It is of more interest, however, for Plato's statement that the deepest truths may not be communicated.

Plato died in 347 B.C., the founder of an important philosophical school, which existed for almost 1, 000 years, and the most brilliant of Socrates's many pupils and followers. His system attracted many followers in the centuries after his death and resurfaced as Neoplatonism, the great rival of early Christianity.

Further Reading

A readable translation of the Platonic corpus may be found in the edition by Benjamin Jowett, The Dialogues of Plato (1953), which contains analyses. Special treatments may be found in J. Burnett, Greek Philosophy (1914); A.E. Taylor, Plato: The Man and His Work (1927); and Paul Shorey, What Plato Said (1933). □

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Plato (427-348 B.C.E.)

Plato (427-348 B.C.E.)

Plato was born into an aristocratic Greek family in the fifth century b.c.e. Like all youngsters of his status, he initially intended to go into politics. In his twenties, he came into the circle of Socrates, who was to be the lasting influence on his thought. After the execution of Socrates on accusations of the corruption of youth, Plato abandoned direct involvement in politics and turned to writing and education. All his works are in the form of dialogues, in most of which the main speaker is Socrates (469-399 b.c.e.). In 385b.c.e. he founded the Academy in Athens, the first known institution of research and higher learning in the Greek world, which he headed until the end of his life. Plato deals with childhood in the context of education. He discusses early education mainly in the Republic, written about 385 b.c.e., and in the Laws, his last work, on which he was still at work at the end of his life.

The State as an Educational Entity

Plato saw the state primarily as an educational entity. In the Republic he discusses the principles of a state that is based on knowledge and reason, personified in the philosopher, and not on mere opinion or desire for power. This state is a strict meritocracy, where the citizen body is divided into the functions (commonly but erroneously called "classes") of producers, auxiliaries (in charge of internal and external security), and philosophers, the last two jointly referred to as "guardians." This book is not so much a blueprint for a future state as a standard by which all states are to be measured. The Republic is concerned with the education of the guardians, but in the Laws, where Plato draws up an actual system of laws for a state conforming as much as possible to that standard, the same education is provided to all citizens, according to their abilities.

Plato devotes much attention to the education of the child as a future citizen. As such, he believes that the child belongs to the state and its education is the responsibility of the state (Republic, bk. 2, 376.) Education must be compulsory for all. State funds should pay for gymnasiums and for instructors, officials, and superintendents in charge of education, both cultural and physical (Laws, bk. 7, 764, 804, 813).

Plato is not concerned with training children for a trade but rather with giving them an education in virtue, which is to produce "a keen desire to become a perfect citizen who knows how to rule and be ruled" in turn (Laws, bk. 1, 643). Reason is man's true nature, but it has to be nurtured from childhood by irrational means. Education is thus the correct channeling of pains and pleasures (Laws, bk. 2, 653), aiming at establishing "a nature in which goodness of character has been well and truly established" so as to breed a familiarity with reason (Republic, bk. 3, 398, 401).

Prenatal and infant care . Plato recommends that the care of the soul and body of the child begin even before birth, with walks prescribed for the pregnant woman. The first five years of life see more growth than the next twenty, necessitating frequent and appropriately graduated exercise. Children should be kept well wrapped up for the first two years of life, but they should be taken to the country or on visits. They should be carried until they are old enough to stand on their own feet, which should happen by the age of three, to prevent subjecting their young limbs to too much pressure. The main importance of movement, however, lies in its influence on the early development of a well-balanced soul (Laws, bk. 7, 758-759), and the cultivation of the body is mainly for the soul's sake (Republic, bk. 3, 411).

Storytelling and literature . Storytelling is the main tool for the formation of character in Plato's view, and begins at an earlier age than physical training. Stories should provide models for children to imitate, and as ideas taken in at an early age become indelibly fixed, the creation of fables and legends for children, true or fictional, is to be strictly supervised. Mothers and nurses are not to scare young children with stories of lamentations, monsters, and the horrors of hell, to avoid making cowards of them. That some such stories are enjoyed as good poetry is all the more reason for keeping them away from children (or even grown men) who should be trained to be free and unafraid of death (Republic, bk. 2, 377-383).

Play . Plato believes that a child's character will be formed while he or she plays. One should resort to discipline, but not such as to humiliate the child. There should be neither a single-minded pursuit of pleasure nor an absolute avoidance of painnot for children and not for expectant mothers (Laws, bk. 7, 792). Luxury makes a child bad-tempered and irritable; unduly savage repression drives children into subserviency and puts them at odds with the world. Children and adults should not imitate base characters when playing or acting, for fear of forming a habit that will become second nature (Republic, bk. 3, 395).

Teachers must provide children with miniature tools of the different trades, so that they can use the children's games to channel their pleasures and desires toward the activities they will engage in when they are adults (Laws, bk. 1, 643). Children are to be brought together for games. The sexes are to be separated at the age of six, but girls too should attend lessons in riding, archery, and all other subjects, like boys. Similarly, both boys and girls should engage in dancing (for developing grace) and wrestling (for developing strength and endurance). Plato attached much importance to children's games: "No one in the state has really grasped that children's games affect legislation so crucially as to determine whether the laws that are passed will survive or not." Change, he maintained, except in something evil, is extremely dangerous, even in such a seemingly inconsequential matter as children's games (Laws, bk. 7, 795-797).

Physical education . "Physical training may take two or three years, during which nothing else can be done; for weariness and sleep are unfavorable to study. At the same time, these exercises will provide not the least important test of character" (Republic, bk. 7, 537). Children who are sturdy enough should go to war as spectators, if one can contrive that they shall do so in safety, so that they can learn, by watching, what they will have to do themselves when they grow up (Republic, bk. 5, 466; bk. 7, 537). Girls should be trained in the same way and learn horseback riding, athletics, and fighting in armor, if only to ensure that if it ever proves necessary the women will be able to defend the children and the rest of the population left behind (Laws, bk. 7, 804-805,813).

Reading and writing, music, arithmetic . In Plato's educational system, a child, beginning at the age of ten, will spend three years on reading, writing, and the poets, and another three learning the lyre, and will study elementary mathematics up to the age of seventeen or eighteen, all with as little compulsion as possible, in order to learn "enough to fight a war and run a house and administer a state" (Republic, bk. 7, 535-541). Neither child nor father are to be allowed to extend or curtail that period, either out of enthusiasm or distaste. Children must work on their letters until they are able to read and write, but any whose natural abilities have not developed sufficiently by the end of the prescribed time to make them into quick or polished performers should not be pressed (Laws, bk. 7, 810). The child's lessons should takethe form of play, and this will also show what they are naturally fit for. Enforced exercise does no harm to the body, but enforced learning will not stay in the mind (Laws, bk. 7, 536).

Family Control

In the Republic Plato abolishes the family for the guardians, to avoid nepotism and amassing of private wealth (Republic, bk. 5, 464). Wives and children are to be held in common by all, and no parent is to know his own child nor any child his parents"provided it can be done" (Republic, bk. 5, 457). In the Laws Plato allows family raising for all citizens, with restrictions on child rearing and inheritance (Laws, bk. 5, sec.729). Each family is to have only one heir, to avoid subdivision of the agrarian lots into small parcels. In cases where there is more than one child, the head of the family should marry off the females and the males he must present for adoption to those citizens who have no children of their own"priority given to personal preferences as far as possible." If too many children are being born, measures should be taken to check the increase in population; and in the opposite case, a high birth-rate can be encouraged and stimulated (Laws, bk. 5, 740).

Plato stands at the fountainhead of Western philosophy. He established its themes and posed its problems. Plato's views on education have greatly influenced educational thought to this day and have become the basis of many educational policies. Such diverse thinkers as Montaigne, Jean-Jacques Rousseau, John Dewey, John Stuart Mill, Nietzsche, and many others owe much to Plato's direct influence. His view of philosophy as an educational activity and of education as the development of reason, the responsibility of which lies squarely with the state, is still a living educational challenge.

See also: Ancient Greece and Rome; Aristotle.


Marrou, Henri-Irénée. 1956. A History of Education in Antiquity. Trans. George Lamb. New York: Sheed and Ward.

Plato. 1941 [385 b.c.e.]. The Republic of Plato. Trans. Francis Macdonald Cornford. New York: Oxford University Press.

Plato. 1970 [348 b.c.e.]. The Laws. Trans. Trevor J. Saunders. Harmondsworth, UK: Penguin.

Scolnicov, Samuel. 1988. Plato's Metaphysics of Education. London: Routledge.

Samuel Scolnicov

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Plato 427–347 BCE

Plato 427347 BCE


Plato was born in Athens in 427 bce just as the Peloponnesian War between Athens and Sparta was beginning. His mother was related to one of the oligarchs who ruled Athens after the Spartan victory in 404 bce, and his father died when Plato was very young. The most important shaping influence in Platos early life, however, was the philosopher Socrates (469399 bce). Plato was among the young men of Athens who regularly engaged Socrates in dialogue and who took the Socratic challenge to know thyself very seriously. Plato, then twenty-eight, was present at the trial of Socrates, an event that clearly made a deep and lasting impression on Plato and which is reflected in all of his work. Socrates is widely regarded as the hero of the Platonic dialogues, a literary form that Plato preferred for most of his works. Following Socrates death, Plato traveled throughout Italy, Sicily, and parts of northern Africa before returning to Athens, where he founded the Academy in about 387 bce. Among Platos pupils there, for twenty years, was Aristotle (384322 bce). Late in life, Plato traveled to Syracuse to educate and inspire a new young king, Dionysius II, though the attempt ended in failure. Plato died in Athens in 347 bce at the age of eighty-one.

Among the more famous of Platos dialogues are the Apology, Crito, and Euthyphro, on the trial and death of Socrates; the Gorgias, which explores the way of life of the sophist; the Symposium, which focuses on love and beauty; the Phaedrus, on rhetoric; and the Timaeus, a study of cosmology. Other dialogues of note that are still widely read and studied today are the Meno, Protagoras, Phaedo, Thaetetus, and the Sophist. All of these deal in various ways with Platos famous theory of forms, according to which aspects of the physical world, because subject to decay and death, are inferior to eternal forms such as the true, the good, and the beautiful. But Platos most famous dialogues, and those that continue to shape international discussion and research in the social sciences, in some measure at least, particularly in political science, are the Republic, the Statesman, and the Laws.

The Republic is considered one of the great works of world literature. It is often referred to as an example of utopian literature, which sketches an ideal polis, or citystate. Such a view distorts, however, what Plato clearly intended as an exploration of what human beings mean when they appeal to justice and to good rule or government. Similarly, the Republic is frequently summarized as an appeal for the rule of philosopher kings. This too obscures, at a minimum, Platos belief in gender equality among philosopher rulers, not necessarily kings. Like any classic work, it is difficult to condense and summarize Platos Republic. But there are key aspects that may be sketched along the following lines. At the center of Platos political theory is a concept of the cardinal virtues. These virtues are moderation, or temperance, courage, wisdom, and justice. Following a procedure according to which the state (city-state) is the human person writ large, Plato examines the cardinal virtues both with respect to the individual person and with respect to the larger city-state. Ultimately, a just society for Plato is a society of just persons. And individuals are just according to their capacity with respect to each of the cardinal virtues. Another important concept in the Republic is the three waves, which refer to perennial issues in all societies at all times. These waves represent the issues of gender, property relations, and who should rule. In the dialogue, Socrates argues on behalf of gender equality; for a community of goods and spouses for the guardians of the polis, a group further divided according to warriors (auxiliaries ) and rulers (philosopher rulers ); and for the rule of philosophers. A full measure of justice is possible for Plato only when philosophers become rulers or rulers become philosophers.

Perhaps the most famous passages in the Republic are those that present the allegories of the divided line, from Book VI, and the cave, from Book VII. According to the divided line, human consciousness develops well or poorly according to a progression from imagination, to belief, to understanding, to reason based on consciousness of the good. This same progression is illustrated in the famous cave allegory, where we must imagine human beings chained and facing a cave wall, see them believe in the images projected on that wall from a fire behind their backs, understand that there might be more to reality than what such images suggest to the cave dwellers, and have the courage and capacity, unlike most of those in the cave, to turn around, see the drama to our backs, and theirs, and make our way out of the cave to a transcendent reality that, for Plato, must ultimately inform human reason. These allegories come toward the end of the Republic and summarize and condense what is explored through dialogue in the previous five books (chapters). Toward the end of the dialogue, Plato presents his thoughts on declining forms and censorship. According to the first, regime forms decay over time, such as from aristocracy (rule of the virtuous), to timocracy (rule of those who love honors), to oligarchy (rule of the wealthy), to democracy (rule of those who love freedom), to tyranny (rule of the lustful despot). The final book, Book X, explores the role of the artist in society, among other topics, and the need for some form of censorship.

The Statesman and the Laws represent significant departures from Platos views and style of presentation in the Republic. In the Statesman, for example, an outsider from Elea takes the place of Socrates as the primary spokesperson and the dialogue form is all but abandoned. More significantly, Plato emphasizes a rule of law, or legal codes, as preferable to the rule of philosophers. This shift of emphasis in the Statesman puts Plato more in the tradition of constitutional democracy, with its emphasis on well-constructed constitutions and institutions, characteristic of modern and postmodern approaches to the science of politics. Yet, in the Laws, among Platos last works, which otherwise places a similar emphasis on the need for good laws, one encounters a nocturnal council that would be the final authority in the city-state. Many critics point to this dimension of Platos work to support the idea that Plato was ultimately something of a totalitarian.

The twentieth-century philosopher Alfred North Whitehead (18611947) once famously observed that the European philosophical tradition could be characterized as but a series of footnotes to Plato. Though his influence is not as great in the modern social sciences, there is continuing debate, especially among theorists within the discipline of political science, regarding Platos insights on the role of intellectuals in society; the role of government in promoting excellence, or virtue; the educative function of the state; gender relations; property relations; the role of religion in the state, if any; and the perennial question regarding who should rule and why. And these are but a few of the modern issues regarding which Platos works continue to inspire creative approaches. Some modern scholars, most famously Karl Popper (19021994), see in Platos political theory the seeds of modern tyranny and closed societies. Others, such as John H. Hallowell (19131991), Eric Voegelin (19011985), and James M. Rhodes, see a more balanced and humane approach to the study and practice of politics. Because of his depth of insight and his creative approach to the perennial issues of human beings in their social and political dimensions beyond temporal and cultural considerations, Plato and his legacy will continue to be debated among scholars in all of the modern social sciences into the distant future.


Hallowell, John H. 1965. Plato and his Critics. The Journal of Politics 27 (2): 273289.

Popper, Karl R. 1966. The Spell of Plato. Vol. 1: The Open Society and Its Enemies. 5th rev. ed. Princeton, NJ: Princeton University Press.

Rhodes, James M. 2003. Eros, Wisdom, and Silence: Platos Erotic Dialogues. Columbia: University of Missouri Press.

Strauss, Leo. 1964. The City and Man. Chicago: Rand McNally.

Voegelin, Eric. 2000. Plato and Aristotle. Pt. 1: Plato. Columbia: University of Missouri Press.

Timothy Hoye

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Born: c. 427 b.c.e.
Athens, Greece
Died: c. 347 b.c.e.
Athens, Greece

Greek philosopher

The Greek philosopher Plato founded the Academy in Athens, one of the great philosophical schools of antiquity (ancient times). His thought had enormous impact on the development of Western (having to do with American and European thought) philosophy.

Early life

Plato was born in Athens, Greece, the son of Ariston and Perictione, both of Athenian noble backgrounds. He lived his whole life in Athens, although he traveled to Sicily and southern Italy on several occasions. One story says he traveled to Egypt. Little is known of his early years, but he was given the finest education Athens had to offer noble families, and he devoted his considerable talents to politics and the writing of tragedy (works that end with death and sadness) and other forms of poetry. His acquaintance with Socrates (c. 469c. 399 b.c.e.) altered the course of his life. The power that Socrates's methods and arguments had over the minds of the youth of Athens gripped Plato as firmly as it did many others, and he became a close associate of Socrates.

The end of the Peloponnesian War (43104 b.c.e.), which caused the destruction of Athens by the Spartans, left Plato in a terrible position. His uncle, Critias (c. 480403 b.c.e.), was the leader of the Thirty Tyrants (a group of ruthless Athenian rulers) who were installed in power by the victorious Spartans. One means of holding onto power was to connect as many Athenians as possible with terrible acts committed during the war. Thus Socrates, as we learn in Plato's Apology, was ordered to arrest a man and bring him to Athens from Salamis for execution (to be put to death). When the great teacher refused, his life was threatened, and he was probably saved only by the overthrow of the Thirty Tyrants and the reestablishment of the democracy (a system of government in which government officials are elected by the people).

Death of Socrates

Plato welcomed the restoration of the democracy, but his mistrust was deepened some four years later when Socrates was tried on false charges and sentenced to death. Plato was present at the trial, as we learn in the Apology, but was not present when the hemlock (poison) was given to his master, although he describes the scene in clear and touching detail in the Phaedo. He then turned in disgust from Athenian politics and never took an active part in government, although through friends he did try to influence the course of political life in the Sicilian city of Syracuse.

Plato and several of his friends withdrew from Athens for a short time after Socrates's death and remained with Euclides (c. 450373 b.c.e.) in Megara. His productive years were highlighted by three voyages to Sicily, and his writings, all of which have survived.

The first trip, to southern Italy and Syracuse, took place in 388 and 387 b.c.e., when Plato met Dionysius I (c. 430367 b.c.e.). Dionysius was then at the height of his power in Sicily for having freed the Greeks there from the threat of Carthaginian rule. Plato became better friends with the philosopher Dion (c. 408353 b.c.e.), however, and Dionysius grew jealous and began to treat Plato harshly.

His dialogues

When Plato returned to Athens, he began to teach in the Gymnasium Academe and soon afterward acquired property nearby and founded his famous Academy, which survived until the early sixth century c.e. At the center of the Academy stood a shrine to the Muses (gods of the arts), and at least one modern scholar suggests that the Academy may have been a type of religious brotherhood.

Plato had begun to write the dialogues (writings in the form of conversation), which came to be the basis of his philosophical (having to do with the search for knowledge and truth) teachings, some years before the founding of the Academy. To this early period Plato wrote the Laches which deals with courage, Charmides with common sense, Euthyphro with piety (religious dedication), Lysis with friendship, Protagoras with the teaching of virtues, or goodness, and many others. The Apology and Crito stand somewhat apart from the other works of this group in that they deal with historical events, Socrates's trial and the period between his conviction and execution.

Plato's own great contributions begin to appear in the second group of writings, which date from the period between his first and second voyages to Sicily. The Meno carries on the question of the teachability of virtue first dealt with in Protagoras and introduces the teaching of anamnesis (recollection), which plays an important role in Plato's view of the human's ability to learn the truth.

The Republic

Socrates is again the main character in the Republic, although this work is less a dialogue than a long discussion by Socrates of justice and what it means to the individual and the city-state (independent states). Just as there are three elements to the soul, the rational, the less rational, and the impulsive irrational, so there are three classes in the state, the rulers, the guardians, and the workers. The rulers are not a family of rulers but are made up of those who have emerged from the population as a whole as the most gifted intellectually. The guardians serve society by keeping order and by handling the practical matters of government, including fighting wars, while the workers perform the labor necessary to keep the whole running smoothly. Thus the most rational elements of the city-state guide it and see that all in it are given an education equal to their abilities.

Only when the three work in harmony, with intelligence clearly in control, does the individual or state achieve the happiness and fulfillment of which it is capable. The Republic ends with the great myth of Er, in which the wanderings of the soul through births and rebirths are retold. One may be freed from the cycle after a time through lives of greater and greater spiritual and intellectual purity.

Last years

Plato's third and final voyage to Syracuse was made some time before 357 b.c.e., and he tried for the second time to influence the young Dionysius II. Plato was unsuccessful and was held in semicaptivity before being released. Plato's Seventh Letter, the only one in the collection of thirteen considered accurate, perhaps even from the hand of Plato himself, recounts his role in the events surrounding the death of Dion, who in 357 b.c.e. entered Syracuse and overthrew Dionysius. It is of more interest, however, for Plato's statement that the deepest truths may not be communicated.

Plato died in 347 b.c.e. the founder of an important philosophical school, which existed for almost one thousand years, and the most brilliant of Socrates's many pupils and followers. His system attracted many followers in the centuries after his death and resurfaced as Neoplatonism, the great rival of early Christianity.

For More Information

Kahn, Charles H. Plato and the Socratic Dialogue: The Philosophical Use of a Literary Form. New York: Cambridge University Press, 1996.

Shorey, Paul. What Plato Said. Chicago: University of Chicago Press, 1933.

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(b. Athens, c. 427 BCE.; d. Athens, 348/347 BCE)

physics, cosmology, mathematical education; organization of research. For the original article on Plato see DSB, vol. 11.

One task (although emphatically not the only one) of the DSB original entry was to help the reader judge Plato’s contribution to scientific thought, with a concentration on the mathematical sciences and their strategic role in the philosophical curriculum. In this context, the account of the physical world that Plato offers in the Timaeus is relegated to a subordinate role. This postscript focuses on this account and its contribution to the development of scientific thought.

Plato describes the account of the physical world in the Timaeus as an eikôs muthos or an eikôs logos—that is to say, a likely account, a likely story, or even a myth. What exactly Plato means by this description is open to more than one interpretation. On all interpretations, however, there are distinctively human limitations to what can be said on the topic of the creation of the universe, the nature of the physical world, and the place of humans within it. In other words, one can improve on the account offered in the Timaeus, but one’s account will always remain at best likely. Clearly the limitations that Plato has in mind are not contingent upon historical facts that can eventually be overcome; rather, they have to do with human

nature as well as the nature of the object to be studied, the physical world. Once these limits are acknowledged, the reader is encouraged to engage in the study of the world around us and to produce the best possible account of it.

It is important to situate the Timaeus in the context of the ancient debate on the possibility of the study of nature. In antiquity, there was a philosophical tradition that regarded this study as a vain curiosity, if not a distraction from the care of the soul and the ethical life. In the Memorabilia, for example, Xenophon offers a powerful portrait of Socrates as a champion of this position. This attitude toward the study of nature is often found in the Socratic tradition. In this tradition, the reorientation of philosophy toward ethics is coupled with the emphasis on the limits of human knowledge. This emphasis can be found also in the Timaeus. In this case, however, it does not entail hostility to, or even a rejection of, the empirical sciences. On the contrary, this dialogue offers an account of the physical world, including an account of time, space, matter, and the four elements, as well as human physiology and pathology.

It is mildly surprising to find cosmology and medicine offered as parts of one and the same account. This can be explained by reflecting on the theoretical framework that Plato chose for this account. Plato borrowed this framework from an earlier tradition of writing about the nature of things (the peri physeōs tradition of the sixth and fifth century BCE). In this tradition, the study of the nature of humanity was an essential part of the study of the physical world. Moreover, this study had a narrative character. It did not simply state and explain why the physical world is the way it is; it narrated how the physical world in its present order came into existence. By choosing the narrative method, Plato placed himself in continuity with a tradition going back, ultimately, to early Greek philosophy. This does not necessarily mean that the cosmogonic account offered in the Timaeus has to be taken literally. It is significant that, from very early on, this account was subject to literal as well as non-literal interpretations. On all interpretations, however, the physical world was regarded as the product of a divine craftsman. The task of this divine craftsman was to introduce order into what lacked it. The creation of the physical world was regarded as the result of imposing order on a preexisting matter on the basis of an intelligible model.

The Timaeus can be usefully regarded as Plato’s attempt to reconcile the early investigation of nature with the practical reorientation of philosophy urged by Socrates. But this requires prior clarity about a crucial feature of ancient thought that is no longer shared. The physical world as Plato conceived it is not a value-free world. On the contrary, values are for him part of the furniture of the physical world. The task of the scientist is to attain an understanding of the perfection and goodness of the natural world on the crucial assumption that one can objectively make value judgments about the physical world. In this context, the study of the physical world can provide objective grounds for the view that reason rules over necessity. In light of this conviction, dismissing the study of nature would make it difficult, if not even impossible, to achieve the Socratic goal of caring about the soul.



Complete Works. Edited by John M. Cooper and Douglas S. Hutchinson. Indianapolis, IN: Hackett Publishing, 1997.


Baltes, Matthias. Die Weltenstehung des platonischen “Timaios” nach den antiken Interpreten. 2 vols. Leiden: Brill, 1976–1978.

Brisson, Luc. Le Même et l’Autre dans la Structure Ontologique du “Timée” de Platon. Sankt Augustin, Germany: Academia Verlag, 1994.

Burnyeat, Myles. “Eikôs Muthos.” Rhizai: A Journal for Ancient Philosophy and Science 2, no. 2(2005):143–165.

Carone, Gabriela Roxana. Plato’s Cosmology and its Ethical Dimensions. Cambridge, U.K.: Cambridge University Press, 2005.

Cornford, Francis MacDonald. Plato’s Cosmology. London: Routledge & Kegan Paul, 1937.

Hadot, Pierre. The Veil of Isis: An Essay on the History of the Idea of Nature. Translated by Michael Chase. Cambridge, MA: The Belknap Press of Harvard University Press, 2006. Johansen, Thomas. Plato’s Natural Philosophy: A Study of the Timaeus-Critias. Cambridge, U.K.: Cambridge University Press 2004.

Mohr, Richard. The Platonic Cosmology. Leiden: Brill, 1985.

Reydams-Schils, Gretchen. Plato’s Timaeus as Cultural Icon. Notre Dame, IN: Notre Dame University Press, 2003.

Vlastos, Gregory. Plato’s Universe. Seattle: University of Washington Press, 1975.

Andrea Falcon

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Plato (plā´tō), 427?–347 BC, Greek philosopher. Plato's teachings have been among the most influential in the history of Western civilization.


After pursuing the liberal studies of his day, he became in 407 BC a pupil and friend of Socrates. From about 388 BC he lived for a time at the court of Dionysius the Elder, tyrant of Syracuse. On his return to Athens, Plato founded a school, the Academy, where he taught mathematics and philosophy until his death. His teaching was interrupted by two more visits to Syracuse (367 and 361 BC), which he made in the vain hope of seeing his political ideals realized in Sicily.

Works and Philosophy

Plato was a superb writer, and his works are part of the world's great literature. His extant work is in the form of dialogues and epistles. Some of the dialogues and many of the epistles attributed to him are known to be spurious, while others are doubtful. In the various dialogues he touched upon almost every problem that has occupied subsequent philosophers. The dialogues are divided into three groups according to the probable order of composition.

Early Works

The earliest group of dialogues, called Socratic, include chiefly the Apology, which presents the defense of Socrates; the Meno, which asks whether virtue can be taught; and the Gorgias, which concerns the absolute nature of right and wrong. These early dialogues present Socrates in conversations that illustrate his main ideas—the unity of virtue and knowledge and of virtue and happiness. Each dialogue treats a particular problem without necessarily resolving the issues raised.

Philosophical Themes and Mature Works

Plato was always concerned with the fundamental philosophical problem of working out a theory of the art of living and knowing. Like Socrates, Plato began convinced of the ultimately harmonious structure of the universe, but he went further than his mentor in trying to construct a comprehensive philosophical scheme. His goal was to show the rational relationship between the soul, the state, and the cosmos. This is the general theme of the great dialogues of his middle years: the Republic, Phaedo, Symposium, Phaedrus, Timaeus, and Philebus. In the Republic he shows how the operation of justice within the individual can best be understood through the analogy of the operation of justice within the state, which Plato proceeds to set out in his conception of the ideal state. However, justice cannot be understood fully unless seen in relation to the Idea of the Good, which is the supreme principle of order and truth.

It is in these dialogues that the famous Platonic Ideas (see realism) are discussed. Plato argued for the independent reality of Ideas as the only guarantee of ethical standards and of objective scientific knowledge. In the Republic and the Phaedo he postulates his theory of Forms. Ideas or Forms are the immutable archetypes of all temporal phenomena, and only these Ideas are completely real; the physical world possesses only relative reality. The Forms assure order and intelligence in a world that is in a state of constant flux. They provide the pattern from which the world of sense derives its meaning.

The supreme Idea is the Idea of the Good, whose function and place in the world of Ideas is analogous to that of the sun in the physical world. Plato saw his task as that of leading men to a vision of the Forms and to some sense of the highest good. The principal path is suggested in the famous metaphor of the cave in the Republic, in which man in his uninstructed state is chained in a world of shadows. However, man can move up toward the sun, or highest good, through the study of what Plato calls dialectic. The supreme science, dialectic, is a method of inquiry that proceeds by a constant questioning of assumptions and by explaining a particular idea in terms of a more general one until the ultimate ground of explanation is reached.

The Republic, the first Utopia in literature, asserts that the philosopher is the only one capable of ruling the just state, since through his study of dialectic he understands the harmony of all parts of the universe in their relation to the Idea of the Good. Each social class happily performs the function for which it is suited; the philosopher rules, the warrior fights, and the worker enjoys the fruits of his labor. In the Symposium, perhaps the most poetic of the dialogues, the path to the highest good is described as the ascent by true lovers to eternal beauty, and in the Phaedo the path is viewed as the pilgrimage of the philosopher through death to the world of eternal truth.

Late Works

Many of the late dialogues are devoted to technical philosophic issues. The most important of these are the Theaetetus; the Parmenides, which deals with the relation between the one and the many; and the Sophist, which discusses the nature of nonbeing. Plato's longest work, the Laws, written during his middle and late periods, discusses in practical terms the nature of the state.


See translation of the dialogues by B. Jowett, ed. by D. J. Allan and H. E. Daley (4 vol., 4th ed., rev. 1953); A. E. Taylor, Plato: The Man and His Work (1927); R. Bambrough, ed., New Essays on Plato and Aristotle (1965); G. Vlastos, Platonic Studies (1973); G. F. Else, Plato and Aristotle on Poetry (1987); Jacob A. Kline, A Commentary on Plato's Meno (1989); C. Hampton, Pleasure, Knowledge, and Being: An Analysis of Plato's Philebus (1990); J. E. G. Evans, A Plato Primer (2010).

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The poet Ralph Waldo Emerson once remarked, "Plato is philosophy and philosophy is Plato" (Emerson 1996, p. 21). No less adulation came from the philosopher Alfred North Whitehead, who claimed that Western philosophy was a "series of footnotes to Plato," (Whitehead 1929, p. 63). These kinds of acclamations give one a sense of the major importance of the thinker originally named Aristocles, who came to be called Plato because of his robust figure. Born into one of the most distinguished families in Athens, Plato (428348 b.c.e.) seemed destined for a career in politics. This changed mainly because of the influence of his great mentor Socrates (470399 b.c.e.), who was falsely accused of impiety and corrupting the youth and executed by the state. Becoming distrustful of politics, Plato decided to carry on the philosophical traditions of his mentor. He founded the Academy, considered the first university in Western civilization, and wrote the Dialogues, which continue the eternal questions raised by Socrates.

Plato was especially interested in his mentor's pursuit of real, eternal truths (Justice, Beauty, Goodness), which Plato believed had an existence beyond the mere physical world of flux and change. Accordingly, Plato developed a dualism: There is the physical and changing world (to which the body belongs), and the permanent and immaterial world (to which the mind or soul belongs). The body is then seen as the prisoner and temporary residence of the soul, which has existed before its imprisonment and which will exist again after its release from the body at death. In this way, says Plato, the true philosopher is "always pursuing death and dying" (Emerson 1996, p. 21).

The Dialogues offer a variety of arguments for the immortality of the soul. In the Republic, Plato argues that the soul cannot be destroyed by any inherent evil or by anything external to it. In his Phaedrus he reasons that the soul is its own "selfmoving principle" and is therefore uncreated, eternal, and indestructible. And in the Phaedo a series of arguments are offered based on the cyclical nature of life and death; knowledge the soul could only have gained in a pre-existence; the incorporeal or spiritual nature of the soul; and the view that the soul is the essence and principle of life itself.

The argument regarding the nature of the soul is perhaps the one that gets discussed by scholars most often. If the soul is incorporeal, it is simple or uncomposed (not made up of parts). But death is the decay and corruption of a thing into its elementary parts (decomposition). The soul, therefore, cannot die since an uncomposed entity cannot be decomposed. The logic of this argument is compelling; however, it depends entirely on its key premise: that the soul is spiritual, not corporeal. This is a major point of contention for many, including Plato's greatest studentAristotle (384322 b.c.e.). Though he firmly believed in the immortality of the soul, Plato never considered his arguments to be conclusive proofs and recognized the need for further discussion and consideration, saying that one can only "arrive at the truth of the matter, in so far as it is possible for the human mind to attain it" (Hamilton and Cairns 1961, p. 107).

See also: Philosophy, Western; Plotinus; Socrates


Emerson, Ralph Waldo. "Plato; or, The Philosopher." Representative Men. Cambridge, MA: Harvard University Press, 1996.

Friedlander, Paul. Plato: An Introduction. New York: Harper and Row, 1964.

Plato. The Collected Dialogues of Plato, edited and translated by Edith Hamilton and Huntington Cairns. Princeton, NJ: Princeton University Press, 1961.

Whitehead, Alfred North. Process and Reality. New York: Macmillan, 1929.


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Plato (ca. 428 B.C.–348 B.C.)

Plato (ca. 428 b.c.348 b.c.)

Ancient Greek philosopher who influenced European philosophy and science through the Middle Ages and the Renaissance. Born in Athens, he was the son of a noble family and was given a good education. As a young man he came under the influence of Socrates, a renowned philosopher and debater. Plato experienced firsthand the turmoil of politics in his native city and, after the execution of his friend Socrates on a charge of corrupting the youth of Athens, spent time voyaging to Sicily, then the home of several Greek colonies. When he returned to Athens he founded a school known as the Academy. He began writing dialogues, accounts of debates and conversations among the teachers and philosophers of Athens, with Socrates given an important role. Plato's major work, however, is The Republic, an account of an ideal society in which the virtuous and talented hold leadership and all classes cultivate the virtues of wisdom, courage, and moderation.

Plato's school in Athens survived until the seventh century a.d., and Platonic philosophy remained a dominant strain of thought in the Mediterranean world. While the Roman Empire was at its height, Neoplatonism emerged in the Greek city of Alexandria, founded by several prominent scholars and commentators and based on Plato's metaphysical ideas. Although the philosophy and science of Aristotle dominated the Middle Ages, Plato's writings were also well respected, and in the fifteenth century Platonism was revived in the scholarly investigations of Marsilio Ficino and other Renaissance students of the classical world. Plato's belief in the immortality of the soul, and the ideal Platonic love that existed on a spiritual and not physical plane, attracted Renaissance philosophers and poets who were seeking new ideas complementary to the accepted doctrines of Christianity. Platonism also took an important place in the writings of Giovanni Pico della Mirandola, who attempted a synthesis of many different philosophical and religious traditions, including Platonism, Christianity, and the kabbalah system of Judaism. The Republic inspired the writing of Utopia, an account of an ideal society written by Sir Thomas More. Plato's concept of the universe also made a contribution to the works of Renaissance astronomers such as Johannes Kepler.

See Also: classical literature; Ficino, Marsilio; Neoplatonism; Pico della Mirandola, Giovanni

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Plato (c.429–c.347 bc), Greek philosopher. A disciple of Socrates and the teacher of Aristotle, he founded the Academy in Athens. An integral part of his thought is the theory of ‘ideas’ or ‘forms’, in which abstract entities or universals are contrasted with their objects or particulars in the material world. His philosophical writings are presented in the form of dialogues, with Socrates as the principal speaker; they include the Symposium and the Timaeus. Plato's political theories appear in the Republic, in which he explored the nature and structure of a just society.

Platonism is the philosophy of Plato or his followers; any of various revivals of Platonic doctrines or related ideas, especially Neoplatonism and Cambridge Platonism (a 17th–century attempt to reconcile Christianity with humanism and science).
Platonic love love which is intimate and affectionate but not sexual. The term is recorded in English from the mid 17th century; the equivalent Latin term amor platonicus was used synonymously with amor socraticus by Ficinus (the Florentine Marsilio Ficino, 1433–99), president of Cosmo de' Medici's Accademia Platonica, to denote the kind of interest in young men with which Socrates was credited.
Platonic solid one of five regular solids (i.e., having all sides and all angles equal), a tetrahedron, cube, octahedron, dodecahedron, or icosahedron. Formerly also called Platonic body.
Platonic year a cycle, imagined by some ancient astronomers, in which the heavenly bodies were supposed to go through all their possible movements and return to their original relative positions, after which, according to some, all history would repeat itself (sometimes identified with the period of precession of the equinoxes, about 25,800 years). Also called great year.

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Plato (c.427–c.347 bc) Ancient Greek philosopher and writer who formulated an ethical and metaphysical system based upon philosophical idealism. From c.407 bc, he was a disciple of Socrates, from whom he may have derived many of his ideas about ethics. Following the trial and execution of Socrates in 399 bc, Plato withdrew to Megara, after which he is believed to have travelled extensively in Egypt, Italy and Sicily. He visited Syracuse in Sicily three times, in about 388, 367, and 361–360 bc, during the reigns of the tyrants Dionysius I and II. Plato sought to educate Dionysius II as a philosopher-king and to set up an ideal political system under him, but the venture failed. Meanwhile, in Athens, Plato set up his famous Academy (c.387 bc). In the Academy he taught several young people, including Aristotle. In addition to being a philosopher of great influence, Plato wrote in the form of dialogues, in which Socrates genially interrogates another person, demolishing their arguments. All of Plato's 36 works survive. His most famous dialogues include Gorgias (on rhetoric as an art of flattery), Phaedo (on death and the immortality of the soul) and the Symposium (a discussion on the nature of love). Plato's greatest work was the Republic, an extended dialogue on justice, in which he outlined his view of the ideal state.

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PLATO (or Plato) (ˈpleɪtəʊ) Computing programmed logic for automatic teaching operation

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