The Philosopher King … the Academy … Atlantis … Plato’s Cave … Platonic Love … music of the spheres … the Socratic method … the Ladder of Love … Platonic Forms … Beauty is truth, truth beauty … Platonic Solids … Platonic dialectic … the Third Man … academic freedom … Plato’s Beard … footnotes to Plato …

Get your vaccinations. When you read about Plato’s teacher and his pupils, immunise yourself against authors who have imagined Plato through the lens of a modern schoolroom. When you read of Plato’s master and his disciples, inoculate yourself against authors with a different distorted lens: medieval monasteries with their religious adherents. John Dewey railed against “the artificial Plato constructed by unimaginative commentators” who regard Plato “as the original university professor”. Anyone who purports to provide you with Plato’s teachings, beliefs, or doctrines is doing you a disservice – if you are at all philosophically inclined. This is not to say that Plato was completely without beliefs of his own, but he is not a character in any of his thirty-odd dialogues, so there isn’t much we can be certain about and, if the man’s intention was to persuade others of his personal views, he was blindingly unsuccessful. Controversy sprang up even in ancient times over what Plato really thought, over what should rather be attributed to Socrates or others in the Academy, over which later philosophical schools deserved to be considered the rightful heirs to Plato. If the Republic is your introduction to Plato, you could come away thinking that Plato was the enemy of the arts, a view you wouldn’t hold if you met him through the Symposium or Phaedrus.

It’s common for claims to be made about Plato’s political views by hapless enthusiasts who take the Republic to be Plato’s blueprint for a state, and Plato to have been anti-democratic. How could that happen? Well, it’s a contributing factor that there are far, far more students of politics than students of philosophy on the planet. Add to that the fact that the Republic is a perennial classroom favourite while Plato’s Politicus is a slog, not to mention his tedious Laws, both of which develop the important distinction between lawless and lawful democracies, missing from the Republic. One of Plato’s most admirable qualities, I have come to think, is his incisive but internal critique of the Athenian democracy in which he lived, a democracy he called a golden age compared to the rule of the anti-democratic faction that famously included two older members of his own family. Plato had democratic relatives too, though they are rarely noted. His father, a colonist on Aegina, died about the time Plato was born, but his stepfather was an intimate of Pericles, and named his son, Plato’s step-brother, Demos (people). Never among Athens’ wealthiest citizens, Plato was able to live and write on his agricultural income from an inherited property outside the city walls, later purchasing a second farm nearby. More relevant to his democratic ties, Plato also devoted years to attempts at reforming the tyranny in Syracuse, sailing there after repeated requests from his friend Dion, to assist in an effort to educate the young tyrant, Dionysius II, to make him a just statesman under laws. After failing miserably, Plato turned to supporting the leaders of the democratic faction in overturning the tyranny.

Philosophers these days write articles, articulating and advocating their own positions; but we ought not to let contemporary practice blind us to the ancient genre of the Socratic dialogue (not, by the way, invented by Plato, and practiced by several of Plato’s contemporaries). Socrates was a larger-than-life figure, attractive to the youths of Athens in spite of being irascible, ugly, and lacking in decorum. Aristophanes, the great comic playwright of the time, complained of the dishevelled youths who imitated Socrates by refusing to bathe, going barefoot, letting their hair grow long, carrying sticks, and standing around talking all the time. No doubt, some straightlaced Athenian fathers objected to their sons’ fascination with the man. Plato didn’t deny all that, but emphasised the older man’s unusually consistent character: Socrates held steadfastly to the principle do no harm, not even in return for harm done to you. He was seemingly incorruptible. For Plato too, one must never do wrong, and not only because it is incoherent to say that it is “sometimes right to do wrong.” Throughout Plato’s corpus, Apology to Laws, Plato maintains that no one does wrong willingly – but only thoughtlessly, or in ignorance of what is right – because doing the right thing is always in a person’s best interest, and we seek to do what is in our best interest.

In recent centuries, Plato was taken to be a writer of philosophical fiction, making up characters and situations, or rearranging times and places to fit his narrative ends. Not so. As the results of archaeology, classical studies, and computer-generated comparisons have piled up, it has become clear that Plato’s dialogues are set in real places, populated by real people, evidence of whom can be found elsewhere: in plays, forensic speeches, histories, and on the stones that recorded honours, offices, naval lists, and war casualties in Athens. The characters of Plato’s dialogues are linked by marriage, friendship, and family, by social strata, and by political associations. He would have known some of his characters personally, and others he could only have known by reputation. Unlike, say, Aristotle, Plato ensured that slaves and women were in view in his dialogues, not allowing the listener or reader to forget their presence in the polis. What is remarkable is that there should be only a couple of otherwise unknown – or at least not yet identified – persons among the scores of speakers and onlookers, and that Plato admits comparatively few historical anachronisms into his dialogues. Those tend to be in the longest dialogues, those that show other evidence of editing either by Plato himself or by his academic associates, as was the tradition among the Homerics, Hippocratics, Aristotelians, and other schools. The extent to which Plato tweaked events from memory or others’ reminiscences, or simply fabricated them, is not something we are likely ever to find out. We do know that Plato was about twenty-five when Socrates was executed and that, by that time, he had had many opportunities, probably in the company of his older brothers, to observe Socrates and interact with him. Socrates seems by all accounts to have made himself available to almost anyone willing to engage with him in conversation.

Socrates’ one-on-one oral method of education, when it works, is superior to others because it is deeply personal, affecting, to be questioned and guided by someone who appreciates exactly who you are and what you already understand, eliciting from you more than you knew you had in you. The exclusively oral practice of philosophy, however, had limitations. A casual observer could easily confuse it with the chop-logic of the sophists of the day. On any particular occasion, where an argument might lead depended on who happened to show up, their ability and background, and who undertook the role of respondent. The oral method of question and answer alone is not well suited to the systematic study of past philosophies or the development of a body of positive philosophy. By adding writing to talking, Plato was able to rectify Socratic deficiencies without forfeiting the distinctly personal aspects of the oral method – but I say that thinking that Plato learned from, as much as he led, his friends. By writing dialogues featuring characters with a wide variety of positions, he avoided setting himself up as a sage authority. One encounters in his dialogues queries, dead ends, uncertainty, frustration, confusion, emotional outbursts, and disagreement – rather than dry answers or settled dogma. The real Plato makes you perform your own intellectual labour in interaction with the dialogues, which is not an attractive prospect for most people, especially when his stories and images can be lifted from their context and enjoyed for themselves.

Therein lies the problem with Plato’s legacy: his greatness as a writer has often distracted readers from the gruelling philosophical work that his dialogues propose. Sometimes the characters undertake to try again another day. Sometimes they are reassured that, insofar as understanding something difficult is concerned, it’s better to have tried and failed than never to have tried at all. The excellence we ought to seek, even if it is a kind of knowledge, is not transferrable like knowledge of the Pythagorean theorem or how to tie a shoe, but is achieved dialectically, that is, by working through complex problems with others who are equally serious about the pursuit.

Ancient sources tell us that Plato sought such serious others after Socrates’ execution in 399. Most were mathematically inclined young men whose names are preserved, at first in Athens, then in Megara, then back in Athens where young intellectuals liked to hang out in a grove northwest of the city wall, named for the hero Hecademus. We can surmise that Plato had also begun writing dialogues that had been copied and distributed. Aristophanes lampooned one of them before 391; and Plato, like other notable Athenians, was invited in about 385 to visit Syracuse by the elder tyrant, Dionysius I (father of the Dionysius II mentioned earlier). Plato was disgusted by the excess, decadence, and sensuality of the tyrant’s court, though he had the good fortune of meeting the tyrant’s upright, intelligent young brother-in-law, Dion, who became a life-long friend. Plato offended the tyrant and was promptly shipped off into slavery, not valued for his potential labour but for an anticipated ransom. Anniceris of Cyrene secured Plato’s freedom and refused reimbursement from Plato’s Athenian friends. Rather, he purchased a garden in Hecademus’ grove as a gift for Plato. Thus the Academy began among Plato and his friends, later evolving into a sort of centre for advanced study on numerous topics, attracting young men and women from other parts of Greece.

There is no philosophical topic on which Plato did not write, but one in particular is forever worth our dialectical efforts: that forms exist. Grasped not by the senses but by the intellect, forms are invisible, intelligible, eternal, immutable, and necessary for the existence and nature of all sensible things. Helen Keller, preferring the term idea to form, was sure he was right, “A deaf-blind person ought to find special meaning in Plato’s Ideal World. These things which you see and hear and touch are not the reality of realities, but imperfect manifestations of the Idea, the Principle, the Spiritual; the Idea is the truth, the rest is delusion.” Plato tried and failed in a number of dialogues to offer a coherent theory of forms, if we mean by theory a set of mutually consistent, explanatory principles. One of his best efforts is one of his most famous, the so-called divided line, an argument from the Republic for the existence of forms that has the same structure as medieval first-cause arguments for the existence of god. Its premise is that everything is causally dependent on itself or on something else for its existence. The strategy behind the argument is to determine what is most real and most true by the process of elimination: anything that depends for its existence and truth on something other than itself cannot be ontologically (really) fundamental. I’ll bolster the divided line with a few bits that appear in other dialogues and with other bits from Plato’s friends, including contemporary friends.

Imagine a vertical line cut into four segments. We start with the bottom segment, the level of images, shadows, and reflections. Even puppies and kittenslearn to tell the differencebetween reflections and shadows and the things that cause the reflections or cast the shadows. What the images at the bottom are images of – living puppies and kittens, their toys, and all other perceptible objects – constitute the next higher level. As a member of that second segment myself, I am more stable and reliable than the shadows I cast or my reflection in mirrors. We might note in passing that, if we and other animals and plants are alive, and if the ancients were right to say that what distinguishes me from my corpse is my psyche (what the religious call a soul) then what is visible must somehow encompass what is invisible.

Most people think that what we perceive with our senses, shoes and planets, are the most really real things there are but, according to the argument of the divided line, we cannot have knowledge of these perceptible objects in spacetime; knowledge is limited to what does not change, so there is good reason to doubt the permanence and ultimate reality of physical objects. Optical and auditory illusions warn us that our senses cannot be trusted; sometimes even dreams seem real. More importantly, those objects themselves are in a constant state of change. The acorn becomes the tree that becomes the table that burns into ash and gas over time. Science has contributed more facts, to which contemporary Platonists can help ourselves: objects that appear stable are in motion at the atomic and subatomic levels, and the universe itself is expanding while feeble human beings experience only the Newtonian macro-world. Our senses are unreliable in additional ways: we are limited by our rate of perception, by the number of dimensions in which we operate, and by the puny five senses we have when there may be many ways to perceive the universe.

But back to the immediate argument of the divided line. The most important reason not to take sensibles as absolutely fundamental, is that they do not cause themselves. They do not have independent existence. It is puzzling, perhaps, that the next higher segment of the line is mathematical – puzzling because it is not immediately obvious how mathematics (invisible, intelligible, eternal, immutable) causes physical objects. In Plato’s telling, the second and third segments of the divided line are equal in length. The physical objects on the second level can be exhaustively described by measurements expressed in numbers. My teacup is not a mere heap of matter but a structured sensible entity about which statements roughly describe its composition, its dimensions, its density, its weight at g, and the wavelengths of light its surface reflects. Were there no such perceptible object, those statements would not be accurate.

Yet the contents of the third level are represented as more really real than those of the second. The mathematicals (arithmetic and geometry), logic, and the laws of physics are said to be more real, and statements about them more true, than the sensible particulars of the second level and statements about them. Kurt Gödel insisted on it, “To me a Platonism of this kind, also with respect to mathematical concepts, seems to be obvious and its rejection to border on feeble-mindedness.” Werner Heisenberg concurred, “The elementary particles in Plato’s Timaeus are finally not substance but mathematical forms. … In modern quantum theory there can be no doubt that the elementary particles will finally also be mathematical forms but of a much more complicated nature.” Mathematicians of Plato’s time worked with odd, even, and prime numbers, figures, angles, square roots, addition, subtraction, and so on. These are intelligible, eternal, unchanging, and invisible – even if we would now qualify them by conceding that they are limited to base-ten arithmetic and Euclidean geometry. But we’re not done yet: our mathematical operations depend on definitions and axioms that are not themselves proven, so mathematics is not independent. What then accounts for the truths of mathematics?

Plato’s Socrates in the Republic reasons that a further account is required, that there must be something more fundamental than the formulae manipulated by mathematicians who treat their hypotheses as first principles; that is, there must be an unhypothetical first principle of all that the intellect grasps dialectically, that is causally responsible for everything, forms, numbers, and the sensible objects that mathematicians measure. Once that pinnacle is reached, the fourth and highest segment of the line, the intellect can move back down the divided line and make sound deductions about what was previously understood imperfectly. Not only is my teacup measurable; such forms as being, motion, rest, sameness, and difference characterise it, perhaps the form of the good characterises its function.

You need not agree with my version of the argument of the divided line; what is important is only the recognition that Plato tried out the notion that something like forms are required for a systematic description of what is real and true and intelligible to us – something immune to Heraclitean flux – much as old Parmenides reaffirmed the forms and the power of dialectic to the youthful Socrates in the dialogue named for the old man.

Debra Nails is professor of philosophy emerita at Michigan State University. She is the author of Agora, Academy, and the Conduct of Philosophy (Reidel, 1995), and The People of Plato (Hackett, 2002). She is now a certified EMT in New Jersey.