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When was Plato's Academy founded — 387 or 388 BCE?

Plato founded his Academy in Athens in **387 BCE** by the conventional modern reckoning — but "388 BCE" is not an error, because the ancient evidence points to an Athenian archon year that straddles two of our calendar years and is properly written **388/7 BCE**. No surviving ancient source records a foundation date directly; the year is inferred from Plato's return from his first voyage to Sicily and southern Italy, which ancient chronographers place around his fortieth year (he was born in 428/7 BCE). The honest answer is that the Academy was founded in the 380s BCE, most probably 387, and that anyone quoting 388 is quoting the earlier half of the same split year — or, in a minority of scholarly treatments, dating the school's real beginning a few years later.

The short version: one year, two calendars

The disagreement between 387 BCE and 388 BCE is almost entirely a calendar-conversion artefact, not a dispute about history. The ancient Athenian civil year was named after its chief magistrate, the eponymous archon, and it began in the month Hekatombaion, around midsummer. An archon year therefore covers the second half of one Julian year and the first half of the next. Scholars write such a year with a slash — 388/7 BCE — and readers, editors and encyclopaedias then flatten it to whichever half they prefer.

The same problem affects Olympiad dating, the other framework the ancient chronographers used. Olympiad years also ran from midsummer to midsummer, so "the second year of the 98th Olympiad" maps onto 387/6 BCE rather than onto a single modern year. When you see 387 in one book and 388 in another, you are usually seeing the two ends of one ancient year, not two competing claims.

What the ancient evidence actually says

It is important to be blunt about this: no surviving ancient text states the year Plato founded the Academy. The date is a reconstruction. The chain of inference runs like this. Diogenes Laertius, in his Lives of the Eminent Philosophers (Book III), reports that after Socrates' death Plato travelled — to Megara, then to Egypt, Italy and Sicily — and that he was about forty years old when he visited Sicily and met Dion at the court of Dionysius I of Syracuse. Diogenes says that on his return Plato taught in the gymnasium called the Academy, in the grove sacred to the hero Academus outside the Dipylon Gate.

Plato's birth is placed in 428/7 BCE by the chronology of Apollodorus that Diogenes transmits. Forty years later lands on roughly 388/7. That single arithmetical step is where the conventional date comes from — which is why it is stable to within a year or two and no tighter. Plato's own Seventh Letter describes the first Sicilian visit and its aftermath, and modern chronologies lean on it heavily, though the letter's authenticity has itself been debated for over a century.

Why a minority of scholars date it later

A second, genuinely substantive disagreement sits underneath the calendar one. "Founding the Academy" is a modern phrase for something that probably had no founding moment. Plato did not incorporate a college; he acquired or used property near the public gymnasium of Academus and gathered associates for philosophical discussion. Some historians of the school therefore treat the return from Sicily as the start of Plato's teaching activity but place the emergence of a recognisable institution — with resident members, a shared regimen and a succession — somewhat later in the 380s or even the 370s BCE.

This is why you will occasionally meet dates such as 385 BCE in specialist literature. They are not misprints for 387; they reflect a different question being answered. If the question is when did Plato come back from Sicily and begin teaching at the Academy, the answer is 388/7. If the question is when did the Academy become a school, the answer is a process, not a date.

How to cite the date without being wrong

The safest formulation, and the one used in careful scholarship, is: Plato founded the Academy in Athens in 387 BCE (the archon year 388/7), shortly after returning from his first voyage to Sicily. That sentence is compatible with every mainstream source, flags the calendar convention, and does not overstate the precision of the evidence.

Avoid writing "in exactly 387 BCE" or attributing the date to any ancient author, because none gives it. If a page needs a single number, 387 is the conventional choice; if it needs to be defensible, write 388/7 and explain the slash.

What most scholars accept, and what stays contested

Frequently asked questions

Is 387 BCE or 388 BCE correct for the founding of Plato's Academy?

Both are defensible, because they describe the same Athenian archon year, 388/7 BCE, which ran from midsummer 388 to midsummer 387 BCE. The conventional modern shorthand is 387 BCE. A source printing 388 BCE is normally taking the earlier half of that same year, not making a rival historical claim.

Does any ancient writer state the year Plato founded the Academy?

No. The date is a modern reconstruction. Diogenes Laertius, writing in the third century CE, says Plato was about forty when he sailed to Sicily and that he taught at the Academy after his return; combined with the traditional birth date of 428/7 BCE, that arithmetic yields 388/7 BCE. No surviving text names the year directly.

Why do some books date Plato's Academy to the 380s or 370s BCE instead?

Because they are dating a different thing. Plato did not formally incorporate an institution; he taught in and around the public gymnasium of Academus. Scholars who ask when the Academy became a recognisable school with resident members and a succession sometimes place that development after 387 BCE, which is why dates such as 385 BCE appear in specialist work.

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