Plato (Greek: Πλάτων, Plátōn, "broad") (428/427 BC – 348/347 BC), was a Classical Greek philosopher, who, together with his mentor, Socrates, and his student, Aristotle, helped to lay the foundations of Western philosophy. Plato was also a mathematician, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the western world. Plato was originally a student of Socrates, and was as much influenced by his thinking as by what he saw as his teacher's unjust death.

Plato's sophistication as a writer can be witnessed by reading his Socratic dialogues. Some of the dialogues, letters, and other works that are ascribed to him are considered spurious. Although there is little question that Plato lectured at the Academy that he founded, the pedagogical function of his dialogues, if any, is not known with certainty. The dialogues since Plato's time have been used to teach a range of subjects, mostly including philosophy, logic, rhetoric, mathematics, and other subjects about which he wrote.

Biography

Early life

Birth and family

Plato was born in Athens, Greece. Based on ancient sources, most modern scholars estimate that he was born in Athens or Aegina between 429 and 423 BC His father was Ariston. According to a disputed tradition, reported by Diogenes Laertius, Ariston traced his descent from the king of Athens, Codrus, and the king of Messenia, Melanthus. Plato's mother was Perictione, whose family boasted of a relationship with the famous Athenian lawmaker and lyric poet Solon. Perictione was sister of Charmides and niece of Critias, both prominent figures of the Thirty Tyrants, the brief oligarchic regime, which followed on the collapse of Athens at the end of the Peloponnesian War (404-403 BC). Besides Plato himself, Ariston and Perictione had three other children; these were two sons, Adeimantus and Glaucon, and a daughter Potone, the mother of Speusippus (the nephew and successor of Plato as head of his philosophical Academy). According to the Republic, Adeimantus and Glaucon were older than Plato. Nevertheless, in his Memorabilia, Xenophon presents Glaucon as younger than Plato.

Ariston tried to force his attentions on Perictione, but failed of his purpose; then the ancient Greek god Apollo appeared to him in a vision, and, as a result of it, Ariston left Perictione unmolested. Another legend related that, while he was sleeping as an infant, bees had settled on the lips of Plato; an augury of the sweetness of style in which he would discourse philosophy.

Ariston appears to have died in Plato's childhood, although the precise dating of his death is difficult. Perictione then married Pyrilampes, her mother's brother, who had served many times as an ambassador to the Persian court and was a friend of Pericles, the leader of the democratic faction in Athens. Pyrilampes had a son from a previous marriage, Demus, who was famous for his beauty. Perictione gave birth to Pyrilampes' second son, Antiphon, the half-brother of Plato, who appears in Parmenides.

In contrast to his reticence about himself, Plato used to introduce his distinguished relatives into his dialogues, or to mention them with some precision: Charmides has one named after him; Critias speaks in both Charmides and Protagoras; Adeimantus and Glaucon take prominent parts in the Republic. From these and other references one can reconstruct his family tree, and this suggests a considerable amount of family pride. According to Burnet, "the opening scene of the Charmides is a glorification of the whole [family] connection ... Plato's dialogues are not only a memorial to Socrates, but also the happier days of his own family".

Name

According to Diogenes Laërtius, the philosopher was named Aristocles after his grandfather, but his wrestling coach, Ariston of Argos, dubbed him "Platon", meaning "broad," on account of his robust figure. According to the sources mentioned by Diogenes (all dating from the Alexandrian period), Plato derived his name from the breadth (platytês) of his eloquence, or else because he was very wide (platýs) across the forehead. In the 21st century some scholars disputed Diogenes, and argued that the legend about his name being Aristocles originated in the Hellenistic age.'

Education

Apuleius informs us that Speusippus praised Plato's quickness of mind and modesty as a boy, and the "first fruits of his youth infused with hard work and love of study". Plato must have been instructed in grammar, music, and gymnastics by the most distinguished teachers of his time. Dicaearchus went so far as to say that Plato wrestled at the Isthmian games. Plato had also attended courses of philosophy; before meeting Socrates, he first became acquainted with Cratylus (a disciple of Heraclitus, a prominent pre-Socratic Greek philosopher) and the Heraclitean doctrines.

Later life

Plato may have traveled in Italy, Sicily, Egypt and Cyrene. Said to have returned to Athens at the age of forty, Plato founded one of the earliest known organized schools in Western Civilization on a plot of land in the Grove of Hecademus or Academus. The Academy was "a large enclosure of ground which was once the property of a citizen at Athens named Academus... some, however, say that it received its name from an ancient hero", and it operated until AD 529, when it was closed by Justinian I of Byzantium, who saw it as a threat to the propagation of Christianity. Many intellectuals were schooled in the Academy, the most prominent one being Aristotle.

Plato and Socrates

Plato makes it clear, especially in his Apology of Socrates, that he was one of Socrates' devoted young followers. In that dialogue, Socrates is presented as mentioning Plato by name as one of those youths close enough to him to have been corrupted, if he were in fact guilty of corrupting the youth, and questioning why their fathers and brothers did not step forward to testify against him if he was indeed guilty of such a crime (33d-34a). Later, Plato is mentioned along with Crito, Critobolus, and Apollodorus as offering to pay a fine of 30 minas on Socrates' behalf, in lieu of the death penalty proposed by Meletus (38b). In the Phaedo, the title character lists those who were in attendance at the prison on Socrates' last day, explaining Plato's absence by saying, "Plato was ill" (Phaedo 59b).

The relationship between Plato and Socrates is not unproblematic, however. Aristotle, for example, attributes a different doctrine with respect to the ideas to Plato and Socrates (Metaphysics 987b1–11), but Plato never speaks in his own voice in his dialogues. In the Second Letter, it says, "no writing of Plato exists or ever will exist, but those now said to be his are those of a Socrates become beautiful and new" (341c); if the Letter is Plato's, the final qualification seems to call into question the dialogues' historical fidelity. In any case, Xenophon and Aristophanes seem to present a somewhat different portrait of Socrates than Plato paints. Some have called attention to the problem of taking Plato's Socrates to be his mouthpiece, given Socrates' reputation for irony.

The precise relationship between Plato and Socrates remains an area of contention among scholars.

Philosophy

Recurrent Themes

On Plato's mind is the father-son relationship, the "question" of whether a father's interest in his sons has much to do with how well his sons turn out. A boy in ancient Athens was socially located by his family identity, and Plato often refers to his characters in terms of their paternal and fraternal relationships. Socrates was not a family man, and saw himself as the son of his mother, who was apparently a midwife. A divine fatalist, Socrates mocks men who spent exorbitant fees on tutors and trainers for their sons, and repeatedly ventures the idea that good character is a gift from the gods. Crito reminds Socrates that orphans are at the mercy of chance, but Socrates is unconcerned. In the Theaetetus, he is found recruiting as a disciple a young man whose inheritance has been squandered. Socrates twice compares the relationship of the older man and his boy lover to the father-son relationship (Lysis 213a, Republic 3.403b), and in the Phaedo, Socrates' disciples, towards whom he displays more concern than his biological sons, say they will feel "fatherless" when he is gone. Many dialogues, like these, suggest that man-boy love (which is "spiritual") is a wise man's substitute for father-son biology (which is "bodily").

In several dialogues, Socrates floats the idea that Knowledge is a matter of recollection, and not of learning, observation, or study. He maintains this view somewhat at his own expense, because in many dialogues, Socrates complains of his forgetfulness. Socrates is often found arguing that knowledge is not empirical, and that it comes from divine insight. He is quite consistent in believing in the immortality of the soul, and several dialogues end with long speeches imagining the afterlife. More than one dialogue contrasts knowledge and opinion, perception and reality, nature and custom, and body and soul. The only contrast to this is his Parmenides.

Several dialogues tackle questions about art: Socrates says that poetry is inspired by the muses, and is not rational. He speaks approvingly of this, and other forms of divine madness (drunkenness, eroticism, and dreaming) in the Phaedrus (265a–c), and yet in the Republic wants to outlaw Homer's great poetry, and laughter as well. In Ion, Socrates gives no hint of the disapproval of Homer that he expresses in the Republic. The dialogue Ion suggests that Homer's Iliad functioned in the ancient Greek world as the bible does today in the modern Christian world: as divinely inspired literature that can provide moral guidance, if only it can be properly interpreted.

On politics and art, religion and science, justice and medicine, virtue and vice, crime and punishment, pleasure and pain, rhetoric and rhapsody, human nature and sexuality, love and wisdom, Socrates and his company of disputants had something to say.

Metaphysics

"Platonism" is a term coined by scholars to refer to the intellectual consequences of denying, as Socrates often does, the reality of the material world. In several dialogues, most notably the Republic, Socrates inverts the common man's intuition about what is knowable and what is real. While most people take the objects of their senses to be real if anything is, Socrates is contemptuous of people who think that something has to be graspable in the hands to be real. In the Theaetetus, he says such people are "eu a-mousoi", an expression that means literally, "happily without the muses" (Theaetetus 156a). In other words, such people live without the divine inspiration that gives him, and people like him, access to higher insights about reality.

Socrates's idea that reality is unavailable to those who use their senses is what puts him at odds with the common man, and with common sense. Socrates says that he who sees with his eyes is blind, and this idea is most famously captured in his allegory of the cave, and more explicitly in his description of the divided line. The allegory of the cave (begins Republic 7.514a) is a paradoxical analogy wherein Socrates argues that the invisible world is the most intelligible ("noeton") and that the visible world ("(h)oraton") is the least knowable, and the most obscure. (This is exactly the opposite of what Socrates says to Euthyphro in the soothsayer's namesake dialogue. There, Socrates tells Euthyphro that people can agree on matters of logic and science, and are divided on moral matters, which are not so easily verifiable.)

Socrates says in the Republic that people who take the sun-lit world of the senses to be good and real are living pitifully in a den of evil and ignorance. Socrates admits that few climb out of the den, or cave of ignorance, and those who do, not only have a terrible struggle to attain the heights, but when they go back down for a visit or to help other people up, they find themselves objects of scorn and ridicule.

According to Socrates, physical objects and physical events are "shadows" of their ideal or perfect forms, and exist only to the extent that they instantiate the perfect versions of themselves. Just as shadows are temporary, inconsequential epiphenomena produced by physical objects, physical objects are themselves fleeting phenomena caused by more substantial causes, the ideals of which they are mere instances. For example, Socrates thinks that perfect justice exists (although it is not clear where) and his own trial would be a cheap copy of it.

The allegory of the cave (often said by scholars to represent Plato's own epistemology and metaphysics) is intimately connected to his political ideology (often said to also be Plato's own), that only people who have climbed out of the cave and cast their eyes on a vision of goodness are fit to rule. Socrates claims that the enlightened men of society must be forced from their divine contemplations and compelled to run the city according to their lofty insights. Thus is born the idea of the "philosopher-king", the wise person who accepts the power thrust upon him by the people who are wise enough to choose a good master. This is the main thesis of Socrates in the Republic, that the most wisdom the masses can muster is the wise choice of a ruler.

The word metaphysics derives from the fact that Aristotle's musings about divine reality came after ("meta") his lecture notes on his treatise on nature ("physics"). The term is in fact applied to Aristotle's own teacher, and Plato's "metaphysics" is understood as Socrates' division of reality into the warring and irreconcilable domains of the material and the spiritual. The theory has been of incalculable influence in the history of Western philosophy and religion.

Theory of Forms

The Theory of Forms typically refers to Plato's belief that the material world as it seems to us is not the real world, but only a shadow of the real world. Plato spoke of forms in formulating his solution to the problem of universals. The forms, according to Plato, are roughly speaking archetypes or abstract representations of the many types and properties (that is, of universals) of things we see all around us.

Epistemology

Many have interpreted Plato as stating that knowledge is justified true belief, an influential view which informed future developments in modern analytic epistemology. This interpretation is based on a reading of the Theaetetus wherein Plato argues that belief is to be distinguished from knowledge on account of justification. Many years later, Edmund Gettier famously demonstrated the problems of the justified true belief account of knowledge. This interpretation, however, imports modern analytic and empiricist categories onto Plato himself and is better read on its own terms than as Plato's view.

Really, in the Sophist, Statesman, Republic, and the Parmenides Plato himself associates knowledge with the apprehension of unchanging Forms and their relationships to one another (which he calls "expertise" in Dialectic). More explicitly, Plato himself argues in the Timaeus that knowledge is always proportionate to the realm from which it is gained. In other words, if one derives their account of something experientially, because the world of sense is in flux, the views therein attained will be mere opinions. And opinions are characterized by a lack of necessity and stability. On the other hand, if one derives their account of something by way of the non-sensible forms, because these forms are unchanging, so too is the account derived from them. It is only in this sense that Plato uses the term "knowledge."

In the Meno, Socrates uses a geometrical example to expound Plato's view that knowledge in this latter sense is acquired by recollection. Socrates elicits a fact concerning a geometrical construction from a slave boy, who could not have otherwise known the fact (due to the slave boy's lack of education). The knowledge must be present, Socrates concludes, in an eternal, non-experiential form.

The State

Plato's philosophical views had many societal implications, especially on the idea of an ideal state or government. There is some discrepancy between his early and later views. Some of the most famous doctrines are contained in the Republic during his middle period, as well as in the Laws and the Statesman. However, because Plato wrote dialogues, it is assumed that Socrates is often speaking for Plato. This assumption may not be true in all cases.

Plato, through the words of Socrates, asserts that societies have a tripartite class structure corresponding to the appetite/spirit/reason structure of the individual soul. The appetite/spirit/reason stand for different parts of the body. The body parts symbolize the castes of society.

• Productive Which represents the abdomen.(Workers) — the labourers, carpenters, plumbers, masons, merchants, farmers, ranchers, etc. These correspond to the "appetite" part of the soul.
• Protective Which represents the chest.(Warriors or Guardians) — those who are adventurous, strong and brave; in the armed forces. These correspond to the "spirit" part of the soul.
• Governing Which represents the head. (Rulers or Philosopher Kings) — those who are intelligent, rational, self-controlled, in love with wisdom, well suited to make decisions for the community. These correspond to the "reason" part of the soul and are very few.

According to this model, the principles of Athenian democracy (as it existed in his day) are rejected as only a few are fit to rule. Instead of rhetoric and persuasion, Plato says reason and wisdom should govern. As Plato puts it:

"Until philosophers rule as kings or those who are now called kings and leading men genuinely and adequately philosophise, that is, until political power and philosophy entirely coincide, while the many natures who at present pursue either one exclusively are forcibly prevented from doing so, cities will have no rest from evils,... nor, I think, will the human race." (Republic 473c-d)

Plato describes these "philosopher kings" as "those who love the sight of truth" (Republic 475c) and supports the idea with the analogy of a captain and his ship or a doctor and his medicine. Sailing and health are not things that everyone is qualified to practice by nature. A large part of the Republic then addresses how the educational system should be set up to produce these philosopher kings.

However, it must be taken into account that the ideal city outlined in the Republic is qualified by Socrates as the ideal luxurious city, examined to determine how it is that injustice and justice grow in a city (Republic 372e). According to Socrates, the "true" and "healthy" city is instead the one first outlined in book II of the Republic, 369c–372d, containing farmers, craftsmen, merchants, and wage-earners, but lacking the guardian class of philosopher-kings as well as delicacies such as "perfumed oils, incense, prostitutes, and pastries", in addition to paintings, gold, ivory, couches, a multitude of occupations such as poets and hunters, and war.

In addition, the ideal city is used as an image to illuminate the state of one's soul, or the will, reason, and desires combined in the human body. Socrates is attempting to make an image of a rightly ordered human, and then later goes on to describe the different kinds of humans that can be observed, from tyrants to lovers of money in various kinds of cities. The ideal city is not promoted, but only used to magnify the different kinds of individual humans and the state of their soul. However, the philosopher king image was used by many after Plato to justify their personal political beliefs. The philosophic soul according to Socrates has reason, will, and desires united in virtuous harmony. A philosopher has the moderate love for wisdom and the courage to act according to wisdom. Wisdom is knowledge about the Good or the right relations between all that exists.

Wherein it concerns states and rulers, Plato has made interesting arguments. For instance he asks which is better - a bad democracy or a country reigned by a tyrant. He argues that it is better to be ruled by a bad tyrant (since then there is only one person committing bad deeds) than be a bad democracy (since here all the people are now responsible for such actions.)

According to Plato, a state which is made up of different kinds of souls, will overall decline from an aristocracy (rule by the best) to a timocracy (rule by the honorable), then to an oligarchy (rule by the few), then to a democracy (rule by the people), and finally to tyranny (rule by one person, rule by a tyrant).

Unwritten Doctrine

For a long time Plato's unwritten doctrine has been considered unworthy of attention. Most of the books on Plato seem to diminish its importance. Nevertheless the first important witness who mentions its existence is Aristotle, who in his Physics (209 b) writes: "It is true, indeed, that the account he gives there [i.e. in Timaeus] of the participant is different from what he says in his so-called unwritten teaching (ἄγραφα δόγματα)." The term ἄγραφα δόγματα literally means unwritten doctrine and it stands for the most fundamental metaphysical teaching of Plato which he disclosed only to his most trusted fellows and kept secret from the public.

The reason for not revealing it to everyone is partially discussed in Phaedrus (276 c) where Plato criticizes the written transmission of knowledge as faulty, favoring instead the spoken logos: "he who has knowledge of the just and the good and beautiful ... will not, when in earnest, write them in ink, sowing them through a pen with words which cannot defend themselves by argument and cannot teach the truth effectually." The same argument is repeated in Plato's Seventh Letter (344 c): "every serious man in dealing with really serious subjects carefully avoids writing." In the same letter he writes (341 c): "I can certainly declare concerning all these writers who claim to know the subjects which I seriously study ... there does not exist, nor will there ever exist, any treatise of mine dealing therewith." Such secrecy is necessary in order not "to expose them to unseemly and degrading treatment" (344 d).

It is however said that Plato once disclosed this knowledge to the public in his lecture On the Good (Περὶ τἀγαθοῦ), in which the Good (τὸ ἀγαθόν) is identified with the One (the Unity, τὸ ἕν), the fundamental ontological principle. The content of this lecture has been transmitted by several witnesses, among others Aristoxenus who describes the event in the following words: "Each came expecting to learn something about the things which are generally considered good for men, such as wealth, good health, physical strength, and altogether a kind of wonderful happiness. But when the mathematical demonstrations came, including numbers, geometrical figures and astronomy, and finally the statement Good is One seemed to them, I imagine, utterly unexpected and strange; hence some belittled the matter, while others rejected it." Simplicius quotes Alexander of Aphrodisias who states that "according to Plato, the first principles of everything, including the Forms themselves are One and Indefinite Duality (ἡ ἀόριστος δυάς) which he called Large and Small (τὸ μέγα καὶ τὸ μικρόν) ... one might also learn this from Speusippus and Xenocrates and the others who were present at Plato's lecture on the Good"

Their account is in full agreement with Aristotle's description of Plato's metaphysical doctrine. In Metaphysics he writes: "Now since the Forms are the causes of everything else, he [i.e. Plato] supposed that their elements are the elements of all things. Accordingly the material principle is the Great and Small [i.e. the Dyad], and the essence is the One (τὸ ἕν), since the numbers are derived from the Great and Small by participation in the One" (987 b). "From this account it is clear that he only employed two causes: that of the essence, and the material cause; for the Forms are the cause of the essence in everything else, and the One is the cause of it in the Forms. He also tells us what the material substrate is of which the Forms are predicated in the case of sensible things, and the One in that of the Forms - that it is this the duality (the Dyad, ἡ δυάς), the Great and Small (τὸ μέγα καὶ τὸ μικρόν). Further, he assigned to these two elements respectively the causation of good and of evil" (988 a).

The most important aspect of this interpretation of Plato's metaphysics is the continuity between his teaching and the neoplatonic interpretation of Plotinus or Ficino which has been considered errorneous by many but may in fact have been directly influenced by oral transmission of Plato's doctrine. The first scholar who recognized the importance of the unwritten doctrine of Plato was Heinrich Gomperz who described it in his speech during the 7th International Congress of Philosophy in 1930. All the sources related to the ἄγραφα δόγματα have been collected by Konrad Gaiser and published as Testimonia Platonica. These sources have subsequently been interpreted by scholars from the german Tübingen School such as Hans Joachim Krämer or Thomas A. Szlezák.

Works

Thirty-five dialogues and thirteen letters have traditionally been ascribed to Plato, though modern scholarship doubts the authenticity of at least some of these. Plato's writings have been published in several fashions; this has led to several conventions regarding the naming and referencing of Plato's texts.

The usual system for making unique references to sections of the text by Plato derives from a 16th century edition of Plato's works by Henricus Stephanus. An overview of Plato's writings according to this system can be found in the Stephanus pagination article.

One tradition regarding the arrangement of Plato's texts is according to tetralogies. This scheme is ascribed by Diogenes Laertius to an ancient scholar and court astrologer to Tiberius named Thrasyllus.

In the list below, works by Plato are marked (1) if there is no consensus among scholars as to whether Plato is the author, and (2) if scholars generally agree that Plato is not the author of the work. Unmarked works are assumed to have been written by Plato.

The remaining works were transmitted under Plato's name, most of them already considered spurious in antiquity, and so were not included by Thrasyllus in his tetralogical arrangement. These works are labelled as Notheuomenoi ("spurious") or Apocrypha.

• Axiochus (2), Definitions (2), Demodocus (2), Epigrams, Eryxias (2), Halcyon (2), On Justice (2), On Virtue (2), Sisyphus (2).

Plato's Dialogues

The exact order in which Plato's dialogues were written is not known, nor is the extent to which some might have been later revised and rewritten.

Lewis Campbell was the first to make exhaustive use of stylometry to prove objectively that the Critias, Timaeus, Laws, Philebus, Sophist, and Statesman were all clustered together as a group, while the Parmenides, Phaedrus, Republic, and Theaetetus belong to a separate group, which must be earlier (given Aristotle's statement in his Politics that the Laws was written after the Republic; cf. Diogenes Laertius Lives 3.37). What is remarkable about Campbell's conclusions is that, in spite of all the stylometric studies that have been conducted since his time, perhaps the only chronological fact about Plato's works that can now be said to be proven by stylometry is the fact that Critias, Timaeus, Laws, Philebus, Sophist, and Statesman are the latest of Plato's dialogues, the others earlier.

Increasingly in the most recent Plato scholarship, writers are skeptical of the notion that the order of Plato's writings can be established with any precision, though Plato's works are still often characterized as falling at least roughly into three groups. The following represents one such devision which is relatively common. It should, however, be kept in mind that many of the positions in the ordering are still highly disputed, and also that the very notion that Plato's dialogues can or should be "ordered" is by no means universally accepted.

Early dialogues

Socrates figures in all of these, and they are considered the most faithful representations of the historical Socrates; hence they are also called the Socratic dialogues. Most of them consist of Socrates discussing a subject, often an ethical one (friendship, piety) with a friend or with someone presumed to be an expert on it. Through a series of questions he will show that apparently they do not understand it at all. It is left to the reader to figure out if "he" really understands "it". This makes these dialogues "indirect" teachings.

• Apology
• Charmides
• Crito
• Euthyphro
• Ion
• Laches
• Lesser Hippias
• Lysis
• Menexenus
• Protagoras is often considered one of the last of these "earlier" dialogues.

The following are often considered "transitional" or "pre-middle" dialogues:

• Gorgias
• Meno
• Euthydemus

Middle dialogues

Late in the early dialogues Plato's Socrates actually begins supplying answers to some of the questions he asks, or putting forth positive doctrines. This is generally seen as the first appearance of Plato's own views. The first of these, that goodness is wisdom and that no one does evil willingly, was perhaps Socrates' own view. What becomes most prominent in the middle dialogues is the idea that knowledge comes of grasping unchanging forms or essences, paired with the attempts to investigate such essences. The immortality of the soul, and specific doctrines about justice, truth, and beauty, begin appearing here. The Symposium and the Republic are considered the centrepieces of Plato's middle period. The Parmenides and Theaetetus are often considered to come late in this period and transitional to the next, as they seem to treat the Theory of Forms critically (Parmenides) or not at all (Theaetetus).

• Cratylus
• Phaedo
• Phaedrus
• Symposium
• Republic
• Theaetetus
• Parmenides

Late dialogues

The Parmenides presents a series of criticisms of the theory of Forms which are widely taken to indicate Plato's abandonment of the doctrine. Some recent publications (e.g., Meinwald (1991)) have challenged this characterisation. In most of the remaining dialogues the theory is either absent or at least appears under a different guise in discussions about kinds or classes of things (the Timaeus may be an important, and hence controversially placed, exception). Socrates is either absent or a minor figure in the discussion. An apparently new method for doing dialectic known as "collection and division" is also featured, most notably in the Sophist and Statesman, explicitly for the first time in the Phaedrus, and possibly in the Philebus. A basic description of collection and division would go as follows: interlocutors attempt to discern the similarities and differences among things in order to get clear idea about what they in fact are. One understanding, suggested in some passages of the Sophist, is that this is what philosophy is always in the business of doing, and is doing even in the early dialogues.

The late dialogues are also an important place to look for Plato's mature thought on most of the issues dealt with in the earlier dialogues. There is much work still to be done by scholars on the working out of what these views are. The later works are agreed to be difficult and challenging pieces of philosophy. On the whole they are more sober and logical than earlier works, but may hold out the promise of steps towards a solution to problems which were systematically laid out in prior works.

• Sophist
• Statesman
• Philebus
• Timaeus
• Critias
• Laws

Narration of the dialogues

Plato never presents himself as a participant in any of the dialogues, and with the exception of the Apology, there is no suggestion that he heard any of the dialogues firsthand. Some dialogues have no narrator but have a pure "dramatic" form (examples: Meno, Gorgias, Phaedrus, Crito, Euthyphro), some dialogues are narrated by Socrates, wherein he speaks in first person (examples: Lysis, Charmides, Republic). One dialogue, Protagoras, begins in dramatic form but quickly proceeds to Socrates' narration of a conversation he had previously with the sophist for whom the dialogue is named; this narration continues uninterrupted till the dialogue's end.

The three dialogues, Phaedo, Symposium, and Theaetetus, also begin in dramatic form but then proceed to virtually uninterrupted narration by followers of Socrates, and all, apparently, based on their distant memory or secondhand reports. Phaedo, an account of Socrates' final conversation and hemlock drinking, is narrated by Phaedo to Echecrates in a foreign city many years after the execution took place. The Symposium is narrated by Apollodorus, a Socratic disciple, apparently to Glaucon. Apollodorus assures his listener that he is recounting the story, which took place when he himself was an infant, not from his own memory, but as remembered by Aristodemus, who told him the story years ago. In the beginning of the Theaetetus (142c-143b), Euclides says that he compiled the conversation from notes he took based on what Socrates told him of his conversation with the title character. The rest of the Theaetetus is presented as a "book" written in dramatic form and read by one of Euclides' slaves (143c). Some scholars take this as an indication that Plato had by this date wearied of the narrated form. With the exception of the Theaetetus, Plato gives no explicit indication as to how these orally transmitted conversations came to be written down. Other dialogues, such as the Phaedo, Symposium, and Parmenides, do suggest that such conversations were faithfully recalled and transmitted by Socrates' followers.

Trial of Socrates

The trial of Socrates is the central, unifying event of the great Platonic dialogues. Because of this, Plato's Apology is perhaps the most often read of the dialogues. In the Apology, Socrates tries to dismiss rumors that he is a sophist and defends himself against charges of disbelief in the gods and corruption of the young. Socrates insists that long-standing slander will be the real cause of his demise, and says the legal charges are essentially false. Socrates famously denies being wise, and explains how his life as a philosopher was launched by the oracle at Delphi. He says that his quest to resolve the riddle of the oracle put him at odds with his fellow man, and that this is the reason he has been mistaken for a menace to the city-state of Athens.

Unity and Diversity of the Dialogues

If Plato's important dialogues do not refer to Socrates' execution explicitly, they allude to it, or use characters or themes that play a part in it. Five dialogues foreshadow the trial: In the Theaetetus (210d) and the Euthyphro (2a–b) Socrates tells people that he is about to face corruption charges. In the Meno (94e–95a), one of the men who brings legal charges against Socrates, Anytus, warns him about the trouble he may get into if he does not stop criticizing important people. In the Gorgias, Socrates says that his trial will be like a doctor prosecuted by a cook who asks a jury of children to choose between the doctor's bitter medicine and the cook's tasty treats (521e–522a). In the Republic (7.517e), Socrates explains why an enlightened man (presumably himself) will stumble in a courtroom situation. The Apology is Socrates' defense speech, and the Crito and Phaedo take place in prison after the conviction. In the Protagoras, Socrates is a guest at the home of Callias, son of Hipponicus, a man whom Socrates disparages in the Apology as having wasted a great amount of money on sophists' fees.

Two other important dialogues, the Symposium and the Phaedrus, are linked to the main storyline by characters. In the Apology (19b, c), Socrates says Aristophanes slandered him in a comic play, and blames him for causing his bad reputation, and ultimately, his death. In the Symposium, the two of them are drinking together with other friends. The character Phaedrus is linked to the main story line by character (Phaedrus is also a participant in the Symposium and the Protagoras) and by theme (the philosopher as divine emissary, etc.) The Protagoras is also strongly linked to the Symposium by characters: all of the formal speakers at the Symposium (with the exception of Aristophanes) are present at the home of Callias in that dialogue. Charmides and his guardian Critias are present for the discussion in the Protagoras. Examples of characters crossing between dialogues can be further multiplied. The Protagoras contains the largest gathering of Socratic associates.

In the dialogues for which Plato is most celebrated and admired, Socrates is concerned with human and political virtue, has a distinctive personality, and friends and enemies who "travel" with him from dialogue to dialogue. This is not to say that Socrates is consistent: a man who is his friend in one dialogue may be an adversary or subject of his mockery in another. For example, Socrates praises the wisdom of Euthyphro many times in the Cratylus, but makes him look like a fool in the Euthyphro. He disparages sophists generally, and Prodicus specifically in the Apology, yet tells Theaetetus in his namesake dialogue that he admires Prodicus and has directed many pupils to him. In Cratylus (384b-c), Socrates says that he studied with Cratylus, and took his one-drachma course because he could not afford the full fifty-drachma course. Socrates' ideas are also not consistent within or between or among dialogues.

Platonic Scholarship

Plato's thought is often compared with that of his most famous student, Aristotle, whose reputation during the Western Middle Ages so completely eclipsed that of Plato that the Scholastic philosophers referred to Aristotle as "the Philosopher". However, in the Byzantine Empire, the study of Plato continued.

The Medieval scholastic philosophers did not have access to the works of Plato, nor the knowledge of Greek needed to read them. Plato's original writings were essentially lost to Western civilization until they were brought from Constantinople in the century before its fall, by George Gemistos Plethon. Medieval scholars knew of Plato only through translations into Latin from the translations into Arabic by Persian and Arab scholars. These scholars not only translated the texts of the ancients, but expanded them by writing extensive commentaries and interpretations on Plato's and Aristotle's works (see Al-Farabi, Avicenna, Averroes).

Only in the Renaissance, with the general resurgence of interest in classical civilization, did knowledge of Plato's philosophy become widespread again in the West. Many of the greatest early modern scientists and artists who broke with Scholasticism and fostered the flowering of the Renaissance, with the support of the Plato-inspired Lorenzo de Medici, saw Plato's philosophy as the basis for progress in the arts and sciences. By the 19th century, Plato's reputation was restored, and at least on par with Aristotle's.

Notable Western philosophers have continued to draw upon Plato's work since that time. Plato's influence has been especially strong in mathematics and the sciences. He helped to distinguish between pure and applied mathematics by widening the gap between "arithmetic", now called Number Theory and "logistic", now called arithmetic. He regarded logistic as appropriate for business men and men of war who "must learn the art of numbers or he will not know how to array his troops," while arithmetic was appropriate for philosophers "because he has to arise out of the sea of change and lay hold of true being. Plato's resurgence further inspired some of the greatest advances in logic since Aristotle, primarily through Gottlob Frege and his followers Kurt Gödel, Alonzo Church, and Alfred Tarski; the last of these summarised his approach by reversing Aristotle's famous declaration of sedition from the Nicomachean Ethics (1096a15: Amicus Plato sed magis amica veritas - "Plato is a friend, but truth is a greater friend") to Inimicus Plato sed magis inimica falsitas ("Plato is an enemy, but falsehood is a greater enemy"). Albert Einstein drew on Plato's understanding of an immutable reality that underlies the flux of appearances for his objections to the probabilistic picture of the physical universe propounded by Niels Bohr in his interpretation of quantum mechanics. Conversely, thinkers that diverged from ontological models and moral ideals in their own philosophy, have tended to disparage Platonism from more or less informed perspectives. Thus Friedrich Nietzsche attacked Plato's moral and political theories, Martin Heidegger argued against Plato's alleged obfuscation of Being, and Karl Popper argued in The Open Society and Its Enemies (1945) that Plato's alleged proposal for a government system in the Republic was prototypically totalitarian. Leo Strauss is considered by some as the prime thinker involved in the recovery of Platonic thought in its more political, and less metaphysical, form. Deeply influenced by Nietzsche and Heidegger, Strauss nonetheless rejects their condemnation of Plato and looks to the dialogues for a solution to what all three thinkers acknowledge as 'the crisis of the West.'

See also

• Platonic Realism
• Mitchell Miller
• Eric A. Havelock
• Alexander Nehamas
• Platonic love
• Seventh Letter (Plato)
• Cambridge Platonists
• Jacob Klein (philosopher)
• Seth Benardete

Notes

Citations

References

Primary sources (Greek and Roman)

Secondary sources

Further reading

• Allen, R.E. (2006). Studies in Plato's Metaphysics II. Parmenides Publishing. ISBN 978-1-930972-18-6
• Ambuel, David (2006). Image and Paradigm in Plato's Sophist. Parmenides Publishing. ISBN 978-1-930972-004-9
• Bakalis, Nikolaos (2005). Handbook of Greek Philosophy: From Thales to the Stoics Analysis and Fragments, Trafford Publishing ISBN 1-4120-4843-5
• Barrow, Robin (2007). Plato: Continuum Library of Educational Thought. Continuum. ISBN 0-8264-8408-5.
• Cooper, John M. & Hutchinson, D. S. (Eds.) (1997). Plato: Complete Works. Hackett Publishing Company, Inc. ISBN 0-87220-349-2.
• Corlett, J. Angelo (2005). Interpreting Plato's Dialogues. Parmenides Publishing. ISBN 978-1-930972-02-5
• Durant, Will (1926). The Story of Philosophy. Simon & Schuster. ISBN 0-671-69500-2.
• Derrida, Jacques (1972). La dissémination, Paris: Seuil. (esp. cap.: La Pharmacie de Platon, 69-199) ISBN 2-02-001958-2
• Field, G.C. (Guy Cromwell) (1969). The Philosophy of Plato. 2nd ed. with an appendix by R. C. Cross., London: Oxford University Press.
• Fine, Gail (2000). Plato 1: Metaphysics and Epistemology Oxford University Press, USA, ISBN 0-19-875206-7
• Guthrie, W. K. C. (1986). A History of Greek Philosophy (Plato - The Man & His Dialogues - Earlier Period), Cambridge University Press, ISBN 0-521-31101-2
• Guthrie, W. K. C. (1986). A History of Greek Philosophy (Later Plato & the Academy) Cambridge University Press, ISBN 0-521-31102-0
• Havelock, Eric (2005). Preface to Plato (History of the Greek Mind), Belknap Press, ISBN 0-674-69906-8
• Hamilton, Edith & Cairns, Huntington (Eds.) (1961). The Collected Dialogues of Plato, Including the Letters. Princeton Univ. Press. ISBN 0-691-09718-6.
• Irwin, Terence (1995). Plato's Ethics, Oxford University Press, USA, ISBN 0-19-508645-7
• Jackson, Roy (2001). Plato: A Beginner's Guide. London: Hoder & Stroughton. ISBN 0-340-80385-1.
• Kochin, Michael S. (2002). Gender and Rhetoric in Plato’s Political Thought. Cambridge Univ. Press. ISBN 0-521-80852-9.
• Kraut, Richard (Ed.) (1993). The Cambridge Companion to Plato. Cambridge University Press. ISBN 0-521-43610-9.
• Krämer, Hans Joachim (1990). Plato and the Foundations of Metaphysics. SUNY Press. ISBN 0-791-40433-1.
• Lilar, Suzanne (1954), Journal de l'analogiste, Paris, Éditions Julliard; Reedited 1979, Paris, Grasset. Foreword by Julien Gracq
• Lilar, Suzanne (1963), Le couple, Paris, Grasset. Translated as Aspects of Love in Western Society in 1965, with a foreword by Jonathan Griffin London, Thames and Hudson.
• Lilar, Suzanne (1967) A propos de Sartre et de l'amour , Paris, Grasset.
• Lundberg, Phillip (2005). Tallyho - The Hunt for Virtue: Beauty,Truth and Goodness Nine Dialogues by Plato: Pheadrus, Lysis, Protagoras, Charmides, Parmenides, Gorgias, Theaetetus, Meno & Sophist. Authorhouse. ISBN 1-4184-4977-6.
• Melchert, Norman (2002). The Great Conversation: A Historical Introduction to Philosophy. McGraw Hill. ISBN 0-19-517510-7.
• Meinwald, Constance Chu (1991). Plato's Parmenides. Oxford University Press. ISBN 0-19-506445-3.
• Miller, Mitchell (2004). The Philosopher in Plato's Statesman. Parmenides Publishing. ISBN 978-1-930972-16-2
• Mohr, Richard D. (2006). God and Forms in Plato - and other Essays in Plato's Metaphysics. Parmenides Publishing. ISBN 978-1-930972-01-8
• Moore, Edward (2007). Plato. Philosophy Insights Series. Tirril, Humanities-Ebooks. ISBN 978-1-84760-047-9
• Reale, Giovanni (1990). A History of Ancient Philosophy: Plato and Aristotle. SUNY Press. ISBN 0-791-40516-8.
• Reale, Giovanni (1997). Toward a New Interpretation of Plato. CUA Press. ISBN 0-813-20847-5.
• Sallis, John (1996). Being and Logos: Reading the Platonic Dialogues. Indiana University Press. ISBN 0-253-21071-2.
• Sallis, John (1999). Chorology: On Beginning in Plato's "Timaeus". Indiana University Press. ISBN 0-253-21308-8.
• Sayre, Kenneth M. (2006). Plato's Late Ontology: A Riddle Resolved. Parmenides Publishing. ISBN 978-1-930972-09-4
• Szlezak, Thomas A. (1999). Reading Plato. Routledge. ISBN 0-415-18984-5.
• Taylor, A. E. (2001). Plato: The Man and His Work, Dover Publications, ISBN 0-486-41605-4
• Vlastos, Gregory (1981). Platonic Studies, Princeton University Press, ISBN 0-691-10021-7
• Vlastos, Gregory (2006). Plato's Universe - with a new Introducution by Luc Brisson, Parmenides Publishing. ISBN 978-1-930972-13-1
• Oxford University Press publishes scholarly editions of Plato's Greek texts in the Oxford Classical Texts series, and some translations in the Clarendon Plato Series.
• Harvard University Press publishes the hardbound series Loeb Classical Library, containing Plato's works in Greek, with English translations on facing pages.
• Thomas Taylor has translated Plato's complete works.
• Smith, William. (1867 — original). Dictionary of Greek and Roman Biography and Mythology. University of Michigan/Online version.
• Aspects of antiquity: Discoveries and Controversies by M.I. Finley, issued 1969 by The Viking Press, Inc.
• Interpreting Plato: The Dialogues as Drama by James A. Arieti, Rowman & Littlefield Publishers, Inc. ISBN 0-8476-7662-5

External links

• Works available on-line
• - Greek & English hyperlinked text
• Works of Plato (Jowett, 1892)
• Works by Plato at Project Gutenberg
• Spurious and doubtful works at Project Gutenberg
• Plato complete works, annotated and searchable, at ELPENOR
• Euthyphro LibriVox recording
• Ion LibriVox recording
• Quick Links to Plato's Dialogues (English, Greek, French, Spanish)

• Stanford Encyclopedia of Philosophy:
• Plato
• Plato's Ethics
• Friendship and Eros
• Middle Period Metaphysics and Epistemology
• Plato on Utopia
• Rhetoric and Poetry

• Other Articles:
• Excerpt from W.K.C. Guthrie, A History of Greek Philosophy, vol. IV, Plato: the man and his dialogues, earlier period, Cambridge University Press, 1989, pp. 8-38
• Website on Plato and his works: Plato and his dialogues by Bernard Suzanne
• Are there really Platonic forms?
• "Plato and Totalitarianism: A Documentary Study"
• The New Academy
• Plato Bibliography at PlatoGeek
• Online library "Vox Philosophiae"

PLATO was the first (circa 1960, on ILLIAC I) generalized computer assisted instruction system. It was widely used starting in the early 1970s, with more than 1000 terminals worldwide. PLATO was originally built by the University of Illinois and ran in four decades, offering elementary through university coursework to UIUC students, local schools, and more than a dozen universities.

The project was later taken over by Control Data Corporation (CDC), who built the machines it ran on at the University. CDC President William Norris planned to make PLATO a major force in the computing world, and was a keystone of his ideas about corporate social responsibility. Although the project was economically a failure and supplanted by other technologies by the time the last production PLATO system was turned off in 2006, PLATO nevertheless pioneered key concepts such as online forums and message boards, online testing, email, chat rooms, picture languages, instant messaging, remote screen sharing, and multi-player online games.

The acronym PLATO stands for Programmed Logic for Automated Teaching Operations.

Background

Prior to the 1944 G.I. Bill, which provided free college education to returning World War II veterans, higher education was limited to a minority of the U.S. population. The trend towards much larger enrollment in higher education was clear by the early 1950s, and the problem of providing for an influx of new students was a serious concern. A number of people proposed that if the computer could increase the capabilities of the factory via automation, then surely it could do the same for education.

In 1957 the Soviet Union launched Sputnik I, and the United States suddenly felt a collective sense of educational inferiority. The result was massive spending on science and engineering education; computer-based education along with it. In 1958 the US Air Force's Office of Scientific Research held a conference on the topic at the University of Pennsylvania, and a number of groups—notably IBM—presented studies on the topic.

PLATO's birth

Chalmers Sherwin, a physicist at the University of Illinois, suggested a computerized learning system to William Everett, Dean of the College of Engineering. Everett recommended that Daniel Alpert, another physicist, convene a meeting on the topic that included engineers, educators, mathematicians, and psychologists. After several weeks of meetings the group was unable to suggest a single design for such a system. Alpert was unhappy with the results, but before announcing their failure he mentioned the meetings to a lab assistant, Donald Bitzer. Bitzer claimed that he had already been thinking about the problem, and suggested that he could build a demonstration system.

Bitzer, regarded as the "father of PLATO", succeeded largely due to his rejection of "modern" educational thinking. Returning to a basic drill-based system, his team improved on existing systems by allowing students to bypass lessons they already understood. Their first system, PLATO I first ran on the locally-built ILLIAC I computer in 1960. It included a TV for display and a special keyboard to navigate the system's menus. In 1961 they introduced PLATO II, which ran two users at once.

Convinced of the value of the project, the PLATO system entered a major redesign between 1963 and 1969. The new PLATO III allowed "anyone" to design new lesson modules using their TUTOR programming language, conceived one night in the summer of 1967 by biology grad student Paul Tenczar. Built on a CDC 1604 which had been given to them for free by William Norris, PLATO III could run up to 20 lessons at once, and was used by a number of local facilities in Champaign-Urbana that could be attached to the system with their custom terminals.

NSF involvement

PLATO I, II and III had been funded by small grants from a combined Army-Navy-Air Force funding pool, but by the time PLATO III was in operation everyone involved was convinced it was worthwhile to scale up the project. Accordingly, in 1967 the National Science Foundation granted the team steady funding, allowing Bitzer to set up the Computer-based Education Research Laboratory (CERL) at the university.

In 1972 a new system named PLATO IV was ready for operation. The PLATO IV terminal was a major innovation. It included Bitzer's orange plasma display invention which incorporated both memory and bitmapped graphics into one display. This plasma display included fast vector line drawing capability and ran at 1260 baud, rendering 60 lines or 180 characters per second. The display was a 512x512 bitmap, with both character and vector plotting done by hardwired logic. Users could provide their own characters to support rudimentary raster graphics. Compressed air powered a piston-driven microfiche image selector that permitted colored images to be projected on the back of the screen under program control. The PLATO IV display also included a 16-by-16 grid infrared touch panel allowing students to answer questions by touching anywhere on the screen.

It was also possible to connect the terminal to peripheral devices. One such peripheral was the Gooch Synthetic Woodwind (named after inventor Sherwin Gooch), a synthesizer that offered 4 voice music synthesis to provide sound in PLATO courseware. This was later supplanted on the PLATO V terminal by the Gooch Cybernetic Synthesizer, which had 16 voices that could be programmed individually or combined to make more complex sounds. This allowed for what today is known as multimedia experiences. A PLATO-compatible music language was developed for these synthesizers, as well as a compiler for the language, two music text editors, a filing system for music binaries, programs to play the music binaries in real time, and many debugging and compositional aids. A number of interactive compositional programs have also been written.

Another peripheral was the Votrax speech synthesizer, and a "talk" instruction was added to the Tutor programming language to support it.

The goal of this system was to provide tools for music educators to use in the development of instructional materials, which might possibly include music dictation drills, automatically graded keyboard performances, envelope and timbre ear-training, interactive examples or labs in musical acoustics, and composition and theory exercises with immediate feedback.

With the advent of microprocessor technology, new PLATO terminals were developed to be less expensive and more flexible than the PLATO IV terminals. At the University of Illinois, these were called PLATO V terminals, even though there never was a PLATO V system (the system continued to be called PLATO IV). The Intel 8080 microprocessors in these terminals made them capable of executing programs locally, much like today's Java applets and ActiveX controls, and allowed small software modules to be downloaded into the terminal to augment to the PLATO courseware with rich animation and other sophisticated capabilities that were not available otherwise using a traditional terminal-based approach.

Early in 1972, researchers from Xerox PARC were given a tour of the PLATO system at the University of Illinois. At this time they were shown parts of the system such as the Show Display application generator for pictures on PLATO (later translated into a graphics-draw program on the Xerox Star workstation), and the Charset Editor for "painting" new characters (later translated into a "Doodle" program at PARC), and the Term Talk and Monitor Mode communications program. Many of the new technologies they saw were adopted and improved upon when these researchers returned to Palo Alto, California. They subsequently transferred improved versions of this technology to Apple Inc..

By 1975 the PLATO System served almost 150 locations from a donated CDC Cyber 73, including not only the users of the PLATO III system, but a number of grammar schools, high schools, colleges and universities, and military installations. PLATO IV offered text, graphics and animation as intrinsic components of courseware content, and included a shared-memory construct ("common" variables) that allowed TUTOR programs to send data between various users. This latter construct was used both for chat-type programs, as well as the first multi-user flight simulator.

With the introduction of PLATO IV, Bitzer declared general success, claiming that the goal of generalized computer instruction was now available to all. However the terminals were very expensive (about $12,000), so as a generalized system PLATO would likely need to be scaled down for cost reasons alone.

The CDC years

As PLATO IV reached production quality, William Norris became increasingly interested in it as a potential product. His interest was twofold. From a strict business perspective, he was evolving Control Data into a service-based company instead of a hardware one, and was increasingly convinced that computer-based education would become a major market in the future. At the same time, Norris was upset by the unrest of the late 1960s, and felt that much of it was due to social inequalities that needed to be addressed. PLATO offered a solution by providing higher education to segments of the population that would otherwise never be able to afford university.

Norris provided CERL with machines on which to develop their system in the late 1960s. In 1971 he set up a new division within CDC to develop PLATO "courseware", and eventually many of CDC's own initial training and technical manuals ran on it. In 1974 PLATO was running on in-house machines at CDC headquarters in Minneapolis, and in 1976 they purchased the commercial rights in exchange for a new CDC Cyber machine.

CDC announced the acquisition soon after, claiming that by 1985 50% of the company's income would be related to PLATO services. Through the 1970s CDC tirelessly promoted PLATO, both as a commercial tool and one for re-training unemployed workers in new fields. Norris refused to give up on the system, and invested in several non-mainstream courses, including a crop-information system for farmers, and various courses for inner-city youth. CDC even went as far as to place PLATO terminals in some shareholder's houses, to demonstrate the concept of the system.

In the early 1980s CDC started heavily advertising the service, apparently due to increasing internal dissent over the now $600 million project, taking out print and even radio ads promoting it as a general tool. The Minneapolis Tribune was unconvinced by their ad copy and started an investigation of the claims. In the end they concluded that while it was not proven to be a better education system, everyone using it nevertheless enjoyed it at least. An official evaluation by an external testing agency ended with roughly the same conclusions, suggesting that everyone enjoyed using it, but it was essentially equal to an average human teacher in terms of student advancement.

Of course a computerized system equal to a human should have been a major achievement, the very concept that the early pioneers in CBT were aiming for. A computer could serve all the students in a school for the cost of maintaining it, and wouldn't go on strike. However CDC charged $50 an hour for access to their data center, in order to recoup some of their development costs, making it considerably more expensive than a human on a per-student basis. PLATO was therefore a failure in any real sense, although it did find some use in large companies and government agencies willing to invest in the technology.

An attempt to mass-market the PLATO system was introduced in 1980 as Micro-PLATO, which ran the basic TUTOR system on a CDC "Viking-721" terminal and various home computers. Versions were built for the Texas Instruments TI-99/4A, Atari 8-bit family, Zenith Z-100 and (later)Radio Shack TRS-80 & IBM PC. Micro-PLATO could be used stand-alone for normal courses, or could connect to a CDC data center for multiuser programs. To make the latter affordable, CDC introduced the Homelink service for $5 an hour.

Norris continued to praise PLATO, announcing that it would be only a few years before it represented a major source of income for CDC as late as 1984. In 1986 Norris stepped down as CEO, and the PLATO service was slowly killed off. He later claimed that Micro-PLATO was one of the reasons PLATO got off-track. They had started on the TI-99/4A, but then TI pulled the plug and they moved to other systems like the Atari, who soon did the same. He felt that it was a waste of time anyway, as the system's value was in its online nature, which Micro-PLATO lacked (at least to start).

Bitzer was more forthright about CDC's failure, blaming their corporate culture for the problems. He noted that development of the courseware was averaging $300,000 per delivery hour, many times what the CERL was paying for similar products. This meant that CDC had to charge high prices in order to recoup their costs, prices that made the system unattractive. The reason, he suggested, for these high prices was that CDC had set up a division that had to keep itself profitable via courseware development, forcing them to raise the prices in order to keep their headcount up during slow periods.

PLATO in South Africa

During the period when CDC was marketing PLATO, the system began to be used internationally. South Africa was one of the biggest users of PLATO in the early 1980s. Eskom, the South African electrical power company, had a large CDC mainframe at Megawatt Park in the northwest suburbs of Johannesburg. Mainly this computer was used for management and data processing tasks related to power generation and distribution, but it also ran the PLATO software. The largest PLATO installation in South Africa during the early 1980s was at the University of the Western Cape, which served a "coloured" population, and at one time had hundreds of PLATO IV terminals all connected by leased data lines back to Johannesburg. There were several other installations at educational institutions in South Africa, among them Madadeni College in the Madadeni township just outside of Newcastle.

This was perhaps the most unusual PLATO installation anywhere. Madadeni had about 1,000 students, all of them black and 99.5% of Zulu ancestry. The college was one of 10 teacher preparation institutions in kwaZulu, most of them much smaller. In many ways Madadeni was very primitive. None of the classrooms had electricity and there was only one telephone for the whole college, which one had to crank for several minutes before an operator might come on the line. So an air-conditioned, carpeted room with 16 computer terminals was a stark contrast to the rest of the college. At times the only way a person could communicate with the outside world was through PLATO term-talk.

For many of the Madadeni students, most of whom came from very rural areas, the PLATO terminal was the first time they encountered any kind of electronic technology. (Many of the first year students had never seen a flush toilet before.) There initially was skepticism that these technologically-illiterate students could effectively use PLATO, but those concerns were not borne out. Within an hour or less most students were using the system proficiently, mostly to learn math and science skills, although a lesson that taught keyboarding skills was one of the most popular. A few students even used on-line resources to learn TUTOR, the PLATO programming language, and a few wrote lessons on the system in the Zulu language.

PLATO was also used fairly extensively in South Africa for industrial training. Eskom successfully used PLM (PLATO learning management) and simulations to train power plant operators, South African Airways (SAA) used PLATO simulations for cabin attendant training, and there were a number of other large companies as well that were exploring the use of PLATO.

The South African subsidiary of CDC invested heavily in the development of an entire secondary school curriculum (SASSC) on PLATO, but unfortunately as the curriculum was nearing the final stages of completion, CDC began to falter in South Africa—partly because of financial problems back home, partly because of growing opposition in the United States to doing business in South Africa, and partly due to the rapidly evolving microcomputer, a paradigm shift that CDC failed to recognize.

The PLATO Online Community

Although PLATO was designed for computer-based education, many consider its most enduring legacy to be the online community spawned by its communication features. PLATO Notes, created by David Woolley in 1973, was among the world's first online message boards, and years later became the direct progenitor of Lotus Notes. By 1976, PLATO had sprouted a variety of novel tools for online communication, including Personal Notes (e-mail), Talkomatic (chat rooms), Term-Talk (instant messaging), monitor mode (remote screen sharing) and emoticons.

PLATO's plasma panels were well suited to gaming, although its I/O bandwidth (180 characters per second or 60 graphic lines per second) was relatively slow. By virtue of 1500 shared 60-bit variables per game (initially), it was possible to implement online games. Because it was an educational computer system, most of the user community was keenly interested in gaming.

Many popular inter-terminal games were developed on PLATO during the 1970s and 1980s, such as Empire (a multiplayer game based on Star Trek), Airfight (a precursor to Microsoft Flight Simulator), Panther (a vector graphics based tankwar game, earlier than, but similar in many respects to Atari's BattleZone), the original Freecell, and several games inspired by the role-playing game Dungeons & Dragons, including dnd and Rogue. Moria, Dry Gulch (a western-style variation), and Bugs-n-Drugs (a medical variation) — these all presaged MUDs and MOOs as well as popular first-person shooters like Doom and Quake and MMORPGs like Everquest and World of Warcraft. Avatar, PLATO's most popular game, is one of the world's first MUDs and has over 1 million hours of use.

These communication tools and games formed the basis for an online community of thousands of PLATO users, which lasted for well over twenty years.

In September 2006 the Federal Aviation Administration retired its PLATO system, the last system that ran the PLATO software system on a CDC Cyber mainframe, from active duty. Existing PLATO-like systems now include NovaNET and Cyber1.org.

By early 1976, the original PLATO IV system had 950 terminals giving access to more than 3500 contact hours of courseware, and additional systems were in operation at CDC and Florida State University.. Eventually, over 12,000 contact hours of courseware was developed, much of it developed by university faculty for higher education. PLATO courseware covers a full range of high-school and college courses, as well as topics such as reading skills, family planning, Lamaze training and home budgeting. In addition, authors at the University of Illinois School of Basic Medical Sciences (now, the College of Medicine at Urbana-Champaign) devised a large number of basic science lessons and a self-testing system for first year students. However the most popular "courseware" remained their multi-user games and computer role playing games such as dnd, although it appears CDC was uninterested in this market. As the value of a CDC-based solution disappeared in the 1980s, interested educators ported the engine first to the IBM PC, and later to web-based systems. Today, however, even the web-based versions seem to have disappeared.

Later efforts and other versions

One of CDC's greatest commercial successes with PLATO was an online testing system developed for NASD, a private-sector regulator of the US securities markets. During the 1970s Michael Stein, E. Clarke Porter and PLATO veteran Jim Ghesquiere, in cooperation with NASD executive Frank McAuliffe, developed the first "on-demand" proctored commercial testing service. The testing business grew slowly and was ultimately spun off from CDC as Drake Training and Technologies in 1990. The system was later ported, with help from Novell, to a LAN-based system. Known today as Thomson Prometric, the company has a number of proctored testing sites in the United States where PLATO-like courseware is used for automated testing. E. Clarke Porter left Thomson Prometric, and along with Steve Nordberg and Kirk Lundeen formed Pearson VUE in 1994. Similar to Thomson Prometric, VUE is internet based.

A number of smaller testing-related companies also evolved from the PLATO system. One of the few survivors of that group is The Examiner Corporation. Dr. Stanley Trollip (formerly of the University of Illinois Aviation Research Lab) and Gary Brown (formerly of Control Data) developed the prototype of The Examiner System in 1984.

In the early 1970s, James Schuyler developed a system at Northwestern University called HYPERTUTOR as part of Northwestern's MULTI-TUTOR computer assisted instruction system. This ran on several CDC mainframes at various sites.

Between 1973 and 1980, a group under the direction of Thomas T. Chen at the Medical Computing Laboratory of the School of Basic Medical Sciences at the University of Illinois at Urbana Champaign ported PLATO's TUTOR programming language to the Modcomp IV minicomputer. Douglas W. Jones, A.B. Baskin, Tom Szolyga, Vincent Wu and Lou Bloomfield did most of the implementation. This was the first port of TUTOR to a minicomputer and was largely operational by 1976 In 1980, Chen founded Global Information Systems Technology of Champaign Illinois to market this as the Simpler system. GIST eventually merged with the Defense Training and Technologies division of Adayana Inc Vincent Wu went on to develop the Atari Plato cartridge

CDC eventually sold the "PLATO" trademark and some courseware marketing segment rights to the newly-formed The Roach Organization (TRO) in 1989. In 2000 TRO changed their name to PLATO Learning and continue to sell and service PLATO courseware running on PCs.

CDC continued development of the basic system under the name CYBIS (CYber-Based Instructional System) after selling the trademarks to Roach, in order to service their commercial and government customers. CDC later sold off their CYBIS business to University Online, which was a descendant of IMSATT. University Online was later renamed to VCampus.

The University of Illinois also continued development of PLATO, eventually setting up a commercial on-line service called NovaNET in partnership with University Communications, Inc. CERL was closed in 1994, with the maintenance of the PLATO code passing to UCI. UCI was later renamed NovaNET Learning, which was bought by National Computer Systems (NCS). Shortly after that, NCS was bought by Pearson, and after several name changes now operates as Pearson Digital Learning

Cyber1

In August 2004, a version of PLATO (see Cyber1.org) corresponding to the final release from CDC was resurrected online, and word of its reincarnation spread rapidly. This version of PLATO runs on a software emulation of the original CDC hardware called Desktop CYBER. Within 6 months, by word of mouth alone, more than 500 former users had signed up to use the system. Many of the students who used PLATO in the 1970s and 1980s felt a special social bond with the community of users who came together using the powerful communications tools (talk programs, records systems and notesfiles) on PLATO.

The PLATO software used on Cyber1 is the final release (99A) of CYBIS, by permission of VCampus. The underlying operating system is NOS 2.8.7, the final release of the NOS operating system, by permission of Syntegra (now British Telecom [BT]), which had acquired the remainder of CDC's mainframe business. Cyber1 runs this software on the Desktop CYBER emulator. Desktop CYBER accurately emulates in software a range of CDC CYBER mainframe models and many peripherals.

Cyber1 offers free access to the system, which contains over 16,000 of the original lessons, in an attempt to preserve the original PLATO communities that grew up at CERL and on CDC systems in the 1980s.

Innovation

• Plasma display, circa 1964, by Donald Bitzer for PLATO IV
• Touchscreen, circa 1964, by Donald Bitzer for PLATO IV
• Answer Judging Machinery, ?date?, a set of about 25 commands in TUTOR that made it easy to test a student's understanding of a complex concept.
• Show Display Mode, 1975, a graphics application generator for TUTOR software, precursor to Apple's QuickDraw picture language editor.
• Charset Editor, an early precursor to MacPaint for drawing bitmapped pictures stored in downloadable fonts.
• Monitor Mode on PLATO, 1974, used by instructors to help students, precursor of Timbuktu screen-sharing software.
• Pad and a few months later, system-defined Notesfiles, 1973, the first general-purpose computer message board, and precursor to Unix Newsgroups, Digital DECnotes and Lotus Notes.
• Talkomatic, 1974, a 6-person real-time chat room (text-based), precursor to Instant Messaging Conferences.
• Term-Talk, 1973, precursor to instant messaging.
• Gooch Synthetic Woodwind, circa 1972, A music device for the terminal, precursor to sound cards and MIDI.
• Airfight, 1974, a 3-D flight simulator written for PLATO by Brand Fortner; this probably inspired UIUC student Bruce Artwick to start subLOGIC which was acquired and later became Microsoft Flight Simulator.
• Empire, circa 1974, a 30 person multi-player inter-terminal 2-D real-time space simulation.
• Spasim, circa 1974, a 32-player first-person 3D space battle game
• Pedit5, circa 1974, likely the first graphical dungeon computer game.
• dnd, 1974-1975, a dungeon crawl game that included the first video game boss.
• Panther, circa 1975 by John Haefeli, a 3-D tank simulation and forerunner of Atari's Battlezone game.
• Build-Up, 1976 by Bruce Wallace, based on a story by J. G. Ballard, the first 3-D walkthru maze game. The maze itself was also 3-D, having holes in the floor and ceiling.
• Think15, circa 1977, 2-D outdoor wilderness quest simulation, like Trek with monsters, trees, treasures.
• Avatar, circa 1978, a 2.5-D graphical Multi-User Dungeon (MUD), a precursor to EverQuest.
• Freecell, 1979 by Paul Alfille, which probably spawned the Windows version.
• Mahjong solitaire, 1981 by Brodie Lockard, and was popularised in 1986 by Activision as Shanghai.

See also

• PLATO games

References

External links

• The Plato IV Architecture by Jack Stifle
• PLATO: The Emergence of Online Community by David R. Woolley
• PLATO People, A History Book Research Project by Brian L. Dear
• PLATO: From Computer-Based Education to Corporate Social Responsibility by Elisabeth Van Meer
• PLATO RISING - Online learning for Atarians by David & Sandy Small
• Cyber1.org: An online preservation of the PLATO system
• The History of Computer Gaming Part 5 - PLATO Ain't Just Greek by Marty "Retro Rogue" Goldberg
• Yes Computers can Revolutionize Education by Arthur Darak from the Sept/Oct 1977 issue of Consumer Digest
• Desktop CYBER by Tom Hunter
• Stanley G. Smith and Bruce Arne Sherwood, Educational Uses of the PLATO Computer System, Science 192, 4237 (April 1976), 344-352.
• PLATO User's Guide, Revised April, 1981, CDC Corporation.