Platonism

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In 348/347 BCE Plato died at Athens, and the school he had founded in the grove of Akademos outside the city walls did not die with him. The headship passed to his nephew Speusippus, son of his sister Potone, who led the Academy for eight years before Xenocrates of Chalcedon (c. 396–314 BCE) succeeded him. What passed down with the office was more than a garden and a gathering place: it was the conviction that Plato of Athens (c. 428–348 BCE) had seen the structure of reality, together with a body of dialogues that argue rather than pronounce. Platonism is the long career of that inheritance — the tradition of those who read, defended, quarreled over, and extended Plato, and who made his thought the load-bearing frame of Western metaphysics.

At the center of the inheritance lies a single claim about where reality is most fully found: not in the shifting things the senses report, but in the Forms — the changeless, intelligible patterns of which visible things are imperfect copies. Equal sticks and stones fall short of the Equal itself, and in falling short point beyond themselves, as the Phaedo (74a–75d) shows; the central books of the Republic climb from the many beautiful things to Beauty itself, from acts called just to Justice itself. First among the Forms — “above” them in the image of precedence Plato himself supplies — stands the Good, which the Republic (VI, 507b–509c) compares to the sun: as the sun gives visible things both their generation and the light by which they are seen, so the Good gives the Forms their being and the mind its power to know them, while itself standing, in the dialogue’s vertiginous phrase, beyond being.

From that picture follow the moves that mark the tradition. The soul is kin to the Forms and, in some dialogues, immortal; learning is therefore not the taking-in of something new but anamnesis, recollection of what the soul already knew. The Meno (81c–86b) stages the argument with an untaught boy led step by step to a geometrical truth nobody gives him; the Phaedo (72e–77a) builds recollection into its case that the soul precedes and outlasts the body. Philosophy becomes a turning of the whole soul from appearances toward the real, and ethics rests on the conviction that to know the good truly is to do it — the thesis argued in the Meno (87c–89a) and the Protagoras (352b–358d), sharpest in the dialogues closest to Socrates, complicated but not abandoned when the Republic divides the soul into parts that can pull against one another. The Timaeus completes the picture from above: a divine craftsman looks to the eternal patterns and shapes the visible cosmos after them, setting a soul at its heart, so that the world itself is a living image of the intelligible. How literally Plato meant any of this, and how much shifts across dialogues written over a lifetime, is the question the tradition has carried with it from the beginning; the dialogues stage the arguments and decline to close them.

The corpus that carries all this received its canonical shape in antiquity. Diogenes Laertius records that Thrasyllus arranged the dialogues in tetralogies on the model of the tragic poets — nine of them, thirty-six works, the count reaching fifty-six genuine dialogues if the Republic is divided into its ten books and the Laws into its twelve — and that Aristophanes of Byzantium had earlier sorted part of the corpus into trilogies. Thirteen letters travel with the dialogues, many or most of them almost certainly not Plato’s own; the Seventh Letter, whether by Plato or by someone writing in his name, insists that a philosopher will never commit the deepest things to writing. That insistence has shadowed the tradition ever since, because antiquity also attests — above all through Aristotle — that Plato taught within the Academy principles he never published: the One and the Indefinite Dyad, the so-called unwritten doctrines.

Under its first heirs the Academy pressed this legacy toward number and system. Aristotle reports that Plato, Speusippus, and Xenocrates alike constructed their worlds from two principles, the One and something opposed to it; Speusippus carried the mathematizing furthest, and Xenocrates organized the doctrines into the systematic shape later ages would mine. After Xenocrates the Old Academy ran through Polemo (d. 270/69 BCE) and Crates (d. 268/7), with Crantor (d. 276/5) beside them — and then turned sharply. Arcesilaus of Pitane (315/4–241/40 BCE), scholarch after Crates, led the school for more than twenty-five years and initiated what is called Academic skepticism. Against the Stoic doctrine that certain impressions compel and warrant assent, he argued that nothing can be grasped with certainty (akatalepsia) and recommended the suspension of judgment (epoche); he wrote nothing, delivering his arguments dialectically, in the Socratic manner. On this reading the Platonic inheritance is above all a method — the relentless testing of claims — and Carneades carried it forward through the second century BCE.

The skeptical Academy closed from within. Philo of Larissa (fl. 88–79 BCE), who taught Cicero, softened its rigor; his pupil Antiochus of Ascalon (d. 68 BCE) broke with it outright, proclaiming the fundamental harmony of the Platonic, Peripatetic, and Stoic philosophies and a return to the doctrines of the ancients. With Antiochus opens the period scholars call Middle Platonism — on John Dillon’s landmark map, roughly 80 BCE to 220 CE — in which a confident, doctrinal Platonism returned, drawing freely on Aristotle and the Stoics. Eudorus of Alexandria (fl. c. 25 BCE) fixed its watchword by lifting the goal of life from the Theaetetus (176b): likeness to god, so far as is possible. Philo of Alexandria (c. 30 BCE–45 CE) read Hebrew scripture through Platonic eyes. And the doctrine that organizes the whole period — prepared by Xenocrates — places the Forms as thoughts in the mind of a supreme God: the intelligible patterns live eternally in the divine nous, and the visible world is fashioned upon them.

The period’s voices are distinct. Plutarch of Chaeronea (c. 45–120 CE), Platonist philosopher, made Middle Platonism religious, reading Egyptian cult as Platonic theology in On Isis and Osiris. Numenius of Apamea (mid-to-later second century CE) fused Pythagoras and Plato with the wisdom of the East, asking — in the fragment Clement of Alexandria preserved — “What is Plato but an atticizing Moses?” And the schoolroom itself speaks in the Didaskalikos, the handbook of Platonic doctrine ascribed in the manuscripts to one Alcinous, which sets out God, the Ideas as his thoughts, and the path of likeness in textbook order. For nearly a century scholarship reassigned the handbook to “Albinus” on Jakob Freudenthal’s 1879 conjecture; John Whittaker’s demonstration of 1974, consolidated in his 1990 Budé edition and John Dillon’s 1993 translation, restored the manuscripts’ own Alcinous.

What Middle Platonism prepared, Plotinus (204/5–270 CE) transformed. From his arrival in Rome in 244 descends the systematic reading treated under Neoplatonism — the One beyond being, intellect, soul, emanation, and, in Iamblichus and Proclus, the ritual ascent of theurgy and the full pagan Platonic theology of late antiquity. Numenius’s stamp on Plotinus was remarked in antiquity itself, and the line between late Middle Platonism and early Neoplatonism is one historians draw, not one the ancients marked.

Through those heirs, and through translators and readers in every century since, Platonism became one of the durable structures of Western thought. The Latin West received it through Cicero’s translations, the handbook of Apuleius, Calcidius’s Timaeus, and Boethius — the stream treated under Latin Platonism. The Greek East carried the dialogues from late antiquity to 1453, from Psellos to Plethon, before Byzantine Platonism delivered its manuscripts to Florence. In the Arabic world a paraphrase of Plotinus circulated under Aristotle’s name as the Theology of Aristotle, feeding the Islamic and Jewish Platonic streams, while the Christian stream ran from the Fathers onward. In Florence Marsilio Ficino printed his Latin Plato in 1484, opening the Renaissance recovery of the dialogues; seventeenth-century England produced the Cambridge Platonists; and the vocabulary of an unseen order behind the visible, of the soul’s ascent and of a Good beyond being, runs on through Christian theology, Islamic philosophy, and much later esotericism — often at several removes, and not always under Plato’s name. Even the Gnostic codices found at Nag Hammadi carry a passage of the Republic rendered loosely into Coptic.

The dialogues themselves crossed those centuries by hand. The oldest substantial surviving witness to the text is the Clarke Plato — Bodleian Library, MS. E. D. Clarke 39 — a Greek minuscule codex copied in 895 CE. Print took up the relay at Venice, where the press of Aldus Manutius issued the first printed Greek text, Omnia Platonis opera, in 1513; in 1578 Henri Estienne (Stephanus) published his Platonis opera quae extant omnia at Geneva, and the page numbers and section letters of that edition remain the universal convention for citing Plato. English readers received their first complete Plato in 1804 from Thomas Taylor, completing work begun by Floyer Sydenham; Benjamin Jowett’s The Dialogues of Plato, in its five-volume third edition of 1892, fixed the Victorian standard. The Greek text most readers now open descends from John Burnet’s Oxford Classical Text, whose replacement is under way.

Reading Plato after the Platonists

Modern scholarship on Platonism begins with an act of separation. E. N. Tigerstedt’s The Decline and Fall of the Neoplatonic Interpretation of Plato (Helsinki: Societas Scientiarum Fennica, 1974) traced how the Neoplatonic reading governed interpretation until German scholars of the late eighteenth and nineteenth centuries — Tennemann and Schleiermacher at their head — detached Plato from his Platonist heirs; the very distinction between Platonism and Neoplatonism is, on his showing, an artifact of that detachment.

The same era opened the chronology question. Lewis Campbell’s 1867 Oxford edition of the Sophistes and Politicus began the stylometric line, and Leonard Brandwood’s The Chronology of Plato’s Dialogues (Cambridge: Cambridge University Press, 1990) consolidated it: a group of six late dialogues stands stylistically apart, a result recognized in the nineteenth century and confirmed by computer-aided analysis since.

The fiercest quarrel concerns what Plato did not write. Harold Cherniss’s The Riddle of the Early Academy (1945) denied that Plato taught a systematic oral doctrine and indicted Aristotle as a witness to the Academy’s teaching. The Tübingen school answered with Hans Joachim Krämer’s Arete bei Platon und Aristoteles (Heidelberg: Winter, 1959) and Konrad Gaiser’s Platons ungeschriebene Lehre (Stuttgart: Klett, 1963), reconstructing from Aristotle and the indirect tradition an unwritten teaching of the One and the Indefinite Dyad, Gaiser’s Testimonia Platonica gathering the ancient evidence. The exchange remains the most durable debate in Plato studies.

Two syntheses map the tradition itself. John Dillon’s The Middle Platonists, 80 B.C. to A.D. 220 (London: Duckworth, 1977; revised reprint 1996) established Middle Platonism as a workable period and remains the standard guide to its figures and doctrines. Lloyd P. Gerson’s From Plato to Platonism (Ithaca: Cornell University Press, 2013) presses the older intuition in modern dress, arguing that the later Platonists were right to read Plato as a systematic thinker, whose “Ur-Platonism” Gerson defines by five negations.

The text and the ground keep yielding. Platonis Opera, volume I, edited by E. A. Duke, W. F. Hicken, W. S. M. Nicoll, D. B. Robinson, and J. C. G. Strachan (Oxford: Oxford University Press, 1995), began the replacement of Burnet’s century-old critical text, which remains standard for tetralogies III–IX. And the GreekSchools project — a European Research Council enterprise led by Graziano Ranocchia at the University of Pisa with the CNR, editing Philodemus’s Arrangement of the Philosophers from the carbonized Herculaneum scroll PHerc. 1021, which contains a history of the Academy — announced in April 2024 that hyperspectral imaging had recovered roughly a thousand newly legible words, among them text locating Plato’s burial in the garden of the Academy and new detail on his last hours. These are the announced readings of an edition still in progress, and they are reported as such.

Long before any scroll needed imaging, Diogenes Laertius had written of Plato that “he was buried in the Academy, where he spent the greatest part of his life in philosophical study,” and that the school took its name from the place. The grove of Akademos gave that name first to Plato’s school and, through it, to every academy since; and the scroll that places Plato’s burial in its garden is still being deciphered, word by recovered word, by readers who have not finished with him.

→ In the library: The Dialogues of Plato (Jowett, 1892) · Plato — Meno (Jowett) · Plato — Phaedo (Jowett) · Plato — Timaeus (Jowett) · Plato — Parmenides (Jowett) · Plato — Symposium (Jowett) · Plato — The Seventh Letter (Harward) · Plotinus — The Enneads (MacKenna)

→ Related: Neoplatonism · Plato · Socrates · Aristotle · Pythagoras · Stoicism · The One · Nous · Gnosis · Metaphysics · Universals · Latin Platonism · Byzantine Platonism · Cambridge Platonism · Renaissance Neoplatonism · Numenius Of Apamea · Philo Of Alexandria · Marsilio Ficino · Theurgy · Thomas Taylor