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(plā`tō), 427?–347 B.C., 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 B.C. a pupil and friend of Socrates. From about 388 B.C. 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 Academy,
school founded by Plato near Athens c.387 B.C. It took its name from the garden (named for the hero Academus) in which it was located. Plato's followers met there for nine centuries until, along with other pagan schools, it was closed by Emperor Justinian in A.D. 529.
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, where he taught mathematics and philosophy until his death. His teaching was interrupted by two more visits to Syracuse (367 and 361 B.C.), 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 realism,
in philosophy.

1 In medieval philosophy realism represented a position taken on the problem of universals. There were two schools of realism. Extreme realism, represented by William of Champeaux, held that universals exist independently of both the human
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) 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).


(1) (Programmed Logic for Automatic Teaching Operations) Developed by Donald Bitzer and originally marketed by CDC, it was the first CBT system to combine graphics and touch-sensitive screens for interactive training.

(2) The code name for Microsoft's OLAP extensions to SQL Server. See Microsoft SQL Server OLAP Services.


?427--?347 bc, Greek philosopher: with his teacher Socrates and his pupil Aristotle, he is regarded as the initiator of western philosophy. His influential theory of ideas, which makes a distinction between objects of sense perception and the universal ideas or forms of which they are an expression, is formulated in such dialogues as Phaedo, Symposium, and The Republic. Other works include The Apology and Laws

Plato (427–347 B.C.)

founder of the Academy; author of Republic. [Gk. Hist.: NCE, 2165]


(427–347 B.C.) Greek philosopher revered for wisdom. [Gk. Hist.: NCE, 2165]
See: Wisdom



Born 428 or 427 B.C., in Athens; died there 348 or 347 B.C. Ancient Greek philosopher.

Plato was born into an aristocratic family. In circa 407 he met Socrates and became one of his most enthusiastic pupils. After the death of Socrates, Plato went to Megara. According to tradition, he visited Cyrene and Egypt. In 389 he went to southern Italy and Sicily, where he associated with the Pythagoreans.

Plato founded his own school in Athens (Plato’s Academy). In 367 and 361 he again visited Sicily. In 361 he went there at the invitation of the ruler of Syracuse, Dionysius the Younger, who had expressed his intention of putting Plato’s political ideas into practice. Like Plato’s previous attempts to establish contact with men in power, this trip ended in complete failure. Plato spent the remainder of his life in Athens, where he wrote a great deal and delivered lectures.

Almost all of Plato’s works are dialogues, most of which are conducted by Socrates. In language and composition the dialogues are distinguished for their high literary quality. The early period of Plato’s work (roughly the 390’s B.C.) is represented by the Apology, Crito, Euthyphro, Laches, Lysis, Charmides, Protagoras, and Book 1 of the Republic. The Socratic method of analyzing particular concepts is presented in these dialogues, which are dominated by moral questions. Associated with a transitional period (the 380’s B.C.) is another group of works, including the Gorgias, Meno, Euthydemus, Cratylus, and Hippias Minor, which contain the embryo of the theory of ideas and criticize the relativism of the Sophists. The mature period of Plato’s work (370’s and 360’s B.C.) is represented by the Phaedo, Symposium, and Phaedrus; Books 2–10 of the Republic (the theory of ideas); and the Theaetetus, Parmenides, Sophist, Politi-cus, Philebus, Timaeus, and Critias. In these works Plato shows an interest in problems of structure and logic and presents his theory of epistemology, as well as the dialectics of categories and of the cosmos. The late period of the philosopher’s work (350’s B.C.) is represented by the Laws

Plato’s philosophy is not expounded systematically in his works, which strike the modern scholar as a vast laboratory of thought. Thus, the Platonic system has to be reconstructed. Its most important parts are the theory of the three basic ontological substances (the One, the Intellect, and the Soul) and the related theory of the cosmos. According to Plato, the basis of all being is the One, which in itself is devoid of attributes and parts, has neither beginning nor end, does not occupy space, and cannot move, because motion requires change (that is, plurality). Among the attributes that cannot be applied to the One are identity, difference, and similarity. Nothing can be said of the One, which is higher than all being, sensation, and thinking. Concealed in this source (the One) are not only the ideas (forms, or eide) of things (that is, their substantial spiritual prototypes and principles, to which Plato ascribes an extratemporal reality), but also things themselves and their coming into being, or becoming.

In Plato’s theory the second substance, the Intellect (nous), which is generated by the One (or the Good), consists of being and light. The Intellect, which is pure and unmixed, is carefully differentiated by Plato from everything that is material, physical, and going through the process of becoming: the Intellect is intuitive, and its object is the essence of things, not their becoming. The dialectical conception of the Intellect is completed with a cosmological concept: the Intellect is the generic, mental generalization of all living beings, as well as a living entity, or life itself as manifested in ultimate generalization, order, perfection, and beauty. The Intellect is embodied in the cosmos—specifically, in the regular and eternal movement of the heavens.

The third substance, or World Soul, unites the Intellect and the corporeal world. The Soul receives the laws of its movement from the Intellect, from which it differs in its perpetual mobility —the principle of self-movement. The Intellect is incorporeal and immortal. The Soul, which is immortal and is associated with the truth and the eternal ideas, unites the Intellect with the corporeal world by means of something beautiful, proportioned, and harmonious. The individual soul is the image and outflow of the World Soul. Plato spoke of the immortality or, more precisely, the eternal rejuvenation of the body together with the soul. Death is the transition of the body to another state.

The ideas are the ultimate generalization, meaning, and meaningful essence of things, as well as the very principle by which they are apprehended. Ideas possess not only a logical but also a certain artistic structure. Inherent in them is their own ideal matter, the shaping of which permits them to be comprehended aesthetically. The beautiful also exists in the ideal world as the embodiment of an idea—the ultimate form and intellectual anticipation of all possible approximations of an idea. The beautiful is, in a sense, an organism of an idea, or, more precisely, the idea as an organism. Further dialectical development of the prototype leads to the intellect, soul, and body of the cosmos, resulting in the creation of beauty in its final form for the first time. The cosmos, which perfectly reproduces the eternal prototype or pattern (“paradigm”), is more beautiful than anything else. This doctrine is closely related to the Platonic theory of cosmic proportions.

For Plato, matter is only the principle of a partial functioning of an idea—its abridgment, diminution, or obscuring. Matter is a “receptacle” and “nurse” for ideas. In itself, it is absolutely formless, containing neither earth, water, air, nor any other physical element. Matter is not being; only the ideas are being. Sharply criticizing the separation of ideas from things, Plato formulated the very arguments that Aristotle later directed against alleged Platonic dualism. For Plato, genuine being is ideal being, which exists in itself and is merely “present” in matter. Matter first comes into existence by imitating, associating with, or “participating” in ideal being.

In the last years of his life Plato revised his teaching about the ideas in conformity with Pythagoreanism, seeking the source of the ideas in “ideal numbers.” This trend in his thought was important in the development of Neoplatonism.

The foundation of Plato’s theory of epistemology is the ecstasy of love for the idea. Thus, ecstasy and cognition prove to be an indissoluble whole. With brilliant artistry, Plato depicted the ascent from physical love to love in the realm of souls, and from there to the realm of pure ideas. He interpreted the synthesis of love (eros) and cognition as a special kind of rapture and ecstasy, or erotic enthusiasm, and he gave a mythological description of cognition as the soul’s remembrance of its heavenly birthplace, where it apprehended every idea directly.

For Plato, the basic science that determines all other fields of knowledge is the dialectic—a method of dividing the one into many, of reducing the many to one, and of providing a structural representation of the whole as the many in one. Entering the realm of confused things, the dialectic divides and separates them so that each receives its own meaning and its own idea. The meaning or idea of a thing is taken as the principle of the thing, as its “hypothesis,” its law {nomos), which, according to Plato, leads from diffuse sensibility to an ordered idea, and vice versa. This is precisely the meaning of the “Logos” in Plato’s work. The dialectic, therefore, is a method of establishing the intellectual foundations of things, their objective a priori categories or conceptual forms. The progression from Logos to idea to hypothesis to foundation is also regarded as the limit (the “aim”) of sensory becoming, a universal aim that appears as the Good in the Republic, Philebus, and Gorgias and as Beauty in the Symposium. The limit on the realization (the becoming) of a thing contains a condensed version of the entire formative process of a thing and serves as its blueprint and structure. Thus, Plato’s dialectic is also a theory of indivisible wholes, and as such, it is simultaneously discursive and intuitive. The dialectic can perform all possible logical divisions and at the same time combine everything into one. According to Plato, the dialectician possesses the “combined vision” of the sciences and “sees all at one time.”

The individual soul possesses three capacities—the intellectual, the volitional, and the emotional, of which the first has primacy. In Plato’s ethics there are three corresponding virtues: wisdom, courage, and an illuminated emotional state. They are united into one complete virtue, justice, which represents the equilibrium of its three components.

A similar triadic division is found in Plato’s political thought, in the theory of the three estates: philosophers, who govern on the basis of their contemplation of the ideas; warriors, whose main goal is to defend the state from internal and external enemies; and laborers (peasants and artisans), who give the state material support by supplying it with vital resources. Plato distinguished three principal forms of government: monarchy, aristocracy, and democracy. Each is further subdivided into two forms. A monarchy may be lawful (headed by a king) or based on force (headed by a tyrant). Aristocracy may be the rule of the best or the rule of the worst (oligarchy). Democracy may be lawful or unlawful (based on force). Plato sharply criticized all six forms of government and presented an ideal, Utopian model for state and social organization. According to Plato, kings should be philosophers, and philosophers should be kings. But only a few contemplators of the truth could qualify for this role. Plato developed a detailed theory of social and personal upbringing for the philosophers and warriors, but he did not make it applicable to the “laborers.” He called for the abolition of private property, for the communal sharing of wives and children, for the state regulation of marriages, and for the public upbringing of children, who were not to know the identity of their parents. K. Marx described the utopia presented in Plato’s Republic as “the Athenian idealization of the Egyptian system of castes” (K. Marx and F. Engels, Soch, 2nd ed., vol. 23, p. 379).

In Plato’s aesthetics, beauty is understood as the absolute interpenetration of body, soul, and mind and as the blending of idea and matter, of reason and pleasure, with proportion serving as the guiding principle. Plato does not separate cognition from love or love from beauty (the Symposium, Phaedrus). Thus, all beauty—seen and heard, external or physical—is animated by its own internal life and contains some meaning. Plato regarded beauty in this sense as the ruling force and the source of life for all living things.

For Plato, the beauty of life and real being is superior to that of art. Being and life are the imitation of external ideas; art, an imitation of being and life, is an imitation of an imitation. Consequently, Plato banished Homer from the ideal republic, even though he had greater regard for him than for any other Greek poet. The ideal state was to be a creation of life and not of fantasies, however beautiful. Plato also banned sad, enervating, and Anacreontic music from the ideal state, permitting only martial, courageous, or calming music. Morality and decency are considered necessary conditions for beauty.

Although he did not reject the gods of traditional mythology, Plato demanded that they be philosophically purged of crude, immoral, and fantastic elements. He believed that most of the myths should not be studied by children at an impressionable age. Myth, according to Plato, is symbol. He used mythology to present the periods and ages of the cosmos, the cosmic movement of the gods and of souls in general, and similar phenomena.

Plato is historically important as a philosopher because he consistently thought through the basic principles of objective idealism. Thus, V. I. Lenin termed the entire idealist line in philosophy “the line of Plato” (Poln. sobr. soch, 5th ed., vol. 18, p. 131). Plato’s ideas served as the starting point for a tradition of Platonism and Neoplatonism that has lasted many centuries.


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References in classic literature ?
THE Republic of Plato is the longest of his works with the exception of the Laws, and is certainly the greatest of them.
In what relation the Apology of Plato stands to the real defence of Socrates, there are no means of determining.
The answer which is given by Plato is paradoxical enough, and seems rather intended to stimulate than to satisfy enquiry.