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At the heart of Plato's philosophy is a vision of reality that sees the changing world around us and the things within it as mere shadows or reflections of a separate world of independently existing, eternal, and unchanging entities called “forms” or “ideas.” Ordinary objects are what they are and have the features they do in virtue of their relation to or “participation in” these most fundamental realities. Forms are the proper objects of knowledge or understanding, and the desire to understand them is the proper dominant motivation in a healthy, happy human life. The apprehension and appreciation of formal reality makes life worth living; it also makes one moral.

These views, which find their most vigorous and eloquent expression in the Republic, belong to Plato's philosophical maturity, not his youth. Plato was born in 428 BCE, probably in Athens, to an aristocratic family. His uncle Critias was a leader of the Thirty Tyrants, a group of oligarchs who ruled Athens in 404-403 BCE; another uncle, Charmides, was also one of the Thirty. As a young man Plato encountered Socrates, whose life and death influenced him immensely. After Socrates’ death in 399 BCE, Plato traveled widely, visiting, in particular, Italy and Sicily, where he met Dionysius I, the ruler of Syracuse; Dionysius’s brother-in-law, Dion; and the mathematician Archytus of Tarentum. In 387 BCE, Plato returned to Athens and founded the Academy, where he taught philosophy for most of the rest of his life. He did visit Syracuse twice more. In 367, Dion invited Plato to try to realize the Republic’s ideal of the philosopher-king in the person of Dionysius II, who had just succeeded to the throne. Plato felt obliged to try, but his efforts were unsuccessful. In 362 BCE, Dionysius II himself invited Plato back to teach him philosophy; this visit too was unsuccessful. Plato died in 347 BCE in Athens.

Since there is no work of Plato’s mentioned in antiquity that we do not have, there is reason to think that all of his publications—forty-two dialogues (though scholars doubt the authenticity of several)—survived. There are also thirteen letters and two collections, one of definitions and one of epigrams. Although the authenticity of the letters has been seriously questioned, most scholars rely on the Seventh Letter for important facts about Plato's life.

On the basis of differences in style and doctrine, many scholars believe that Plato's dialogues can be sorted roughly into three groups: a group of “Socratic” dialogues that includes the Apology, Charmides, Crito, Euthydemus, Euthyphro, Gorgias, Greater Hippias, Ion, Laches, Lesser Hippias, Lysis, Menexenus, Meno, and Protagoras; a second group comprising the Cratylus, Parmenides, Phaedo, Phaedrus, Symposium, Republic, and Theaetetus; and a third group including the Critias (apparently not completed by Plato), Laws, Philebus, Sophist, Statesman, and Timaeus. Many also believe that Republic Book 1 was originally composed as a Socratic dialogue and later revised for inclusion in the Republic; some would place the Gorgias in the second group; and a few would include the Timaeus in the second group. Nearly all scholars agree that the dialogues in the third group were written late in Plato's life, and many think that the Socratic dialogues were probably written much earlier, but before the dialogues in the second group. If they are right, Plato's first and second trips to Syracuse may mark the divisions between the three groups.

The Socratic dialogues are dominated by the figure of Socrates. Socrates spent his time talking to people about ethical topics. He sought by this means to discover definitions of the virtues, thinking that in learning what virtue is, he would become virtuous, and that this would make his life a happy one. He also sought to expose other people's false conceit of knowledge about ethical matters, thinking that such conceit prevented them from becoming virtuous and happy. Socrates appealed to some people, but he repelled many others; he also came to be associated in the public mind with anti-democratic factions in Athens. In 399 BCE, Socrates was tried on a charge of impiety, convicted, and put to death.

Socrates plainly had a huge influence on Plato, and the Socratic dialogues seek to memorialize him. Two of them portray the equanimity and moral seriousness with which Socrates conducted himself in his last days. The Apology purports to be the speech Socrates made in defense of his life and conduct at his trial; in the Crito, he gives reasons for rejecting an offer from his friends to get him out of prison and away from Athens before his sentence can be carried out. Another group of dialogues shows Socrates using the method of elenchus or cross-examination to test definitions of the virtues or other moral notions offered by others: the Charmides, a definition of temperance; Euthyphro, of piety; Greater Hippias, of the fine; Laches, of courage; Lysis, of friendship; Meno, of virtue itself; and Republic Book 1, of justice. A third group of dialogues (the Gorgias, Ion, and Protagoras) shows Socrates using the elenchus to refute the moral views of those who claim to have the knowledge he lacks. The question how the views of the historical Socrates, the Socrates of Plato's Socratic dialogues, and Plato himself are related to one another is extremely controversial. One common and reasonable answer is that Plato seeks to remain true to the spirit though not necessarily the letter of the philosophy of the historical Socrates.

In the dialogues of the second group, the theory of forms takes Socrates' place at center stage. Plato abandons the elenchus as well as Socrates' concentration on ethical topics in favor of an ambitious positive doctrine that ranges over the full spectrum of human experience. In the great constructive dialogues of this period—the Phaedo (which describes the day of Socrates' death), the Symposium and the Phaedrus (both on love), and especially the Republic (on the ideal state and the best life for a human being, and much else)—Plato achieves a combination of artistic and philosophical excellence not seen since. In the remaining dialogues of this group, Plato discusses philosophy of language (the Cratylus), philosophy of knowledge (the Theaetetus), and his own theory of forms (the Parmenides).

Plato's last dialogues take up both neglected and previously considered questions. The Sophist addresses difficulties first raised by Parmenides involving not-being and falsity. The Timaeus supplements the middle period's theory of forms to make possible an account of physical reality. The Philebus deals with pleasure, a topic discussed briefly in the Gorgias and the Republic. The Statesman and the Laws (very likely Plato's last work) return to issues in political philosophy, a subject taken up earlier in the Crito and the Republic.

Primary Sources

A complete Greek text of Plato's writings is provided in

John Burnet, ed., Platonis Opera, 5 vols. (Oxford: Clarendon Press, 1900-1907). A Greek text of Plato's writings with translations on facing pages appears in 14 volumes as a part of the Loeb Classical Library. There are also texts, with commentaries, of a number of individual dialogues.

A convenient one-volume translation (by various hands) of all of Plato's writings (including works attributed to Plato that he may not have written) is

J. Cooper, ed., Plato: Complete Works (Indianapolis and Cambridge: Hackett Publishing Company, 1997); it supersedes

E. Hamilton and H. Cairns, eds., The Collected Dialogues of Plato (New York: Pantheon, 1961; Princeton, N.J.: Princeton University Press, 1971). Translations of various individual dialogues, some with commentary, are published by Penguin Books and Hackett Publishing Company. Translations with commentaries also appear in the Clarendon Plato Series.

The standard way to refer to Plato's writing is by "Stephanus number," which gives the page number, section of page, and line number within the section of an early edition of Plato's writings. These numbers are given in the margins of Burnet's text and most other texts and translations.

Secondary Sources

General accounts of Socrates and Plato include:

    Crombie, I. M. An Examination of Plato's Doctrines. 2 vols. London: Routledge & Kegan Paul, 1962, 1963. Friedlhander, P. Plato. Trans. H. Meyerhoff. 3 vols. 2nd edition. Princeton, N.J.: Princeton University Press, 1969. Gosling, J. C. B. Plato. London: Routledge & Kegan Paul, 1973. Guthrie, W. K. C. A History of Greek Philosophy. Vols. 3-5. Cambridge, Eng.: Cambridge University Press, 1969, 1975, 1978. Hare, R. M. Plato. Oxford: Oxford University Press, 1982. Rowe, C. J. Plato. New York: St. Martin's Press, 1984. Santas, G. X. Socrates. London: Routledge & Kegan Paul, 1969. Shorey, P. The Unity of Plato's Thought. Chicago: University of Chicago Press, 1960. What Plato Said. Chicago: University of Chicago Press, 1933. Skemp, J. B. Plato. Oxford: Clarendon Press, 1976. Taylor, A. E. Plato. London: A. Constable, 1914. Socrates. London: New York: T. Nelson, 1939. Vlastos, G. Platonic Studies. 2nd ed. Princeton, N.J.: Princeton University Press, 1981. Socrates, Ironist and Moral Philosopher. Ithaca, N.Y.: Cornell University Press, 1991.
Since Plato wrote dialogues rather than treatises, the interpretation of his writings raises special problems. Some of these are discussed in:

    Griswold, Charles L., Jr., ed. Platonic Writings, Platonic Readings. New York: Routledge & Kegan Paul, 1988.
Two collections of some of the best of the secondary literature on Socrates and Plato are:

    Vlastos, G., ed. Plato: A Collection of Critical Essays. 2 vols.Garden City, N.Y.: Anchor Books, 1970. The Philosophy of Socrates: A Collection of Critical Essays. Garden City, N.Y.: Anchor Books, 1971.
A collection of recent articles on Plato, with an extensive bibliography, is:

    Kraut, R., ed. The Cambridge Companion to Plato. Cambridge: Cambridge University Press, 1992.
Charles M. Young, Claremont Graduate University

Plato (2), son of Lycaon

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