428 BC

Plato

Birth of Plato

Ancient calculations place Plato's birth in at least three different years — and one tradition handed him Apollo's own birthday, the seventh of Thargelion.

A birth reconstructed, not recorded

Plato was probably born in 428/427 BCE into a wealthy, politically connected Athenian family. The year is reconstructed from later chronological testimony rather than securely recorded, and no detailed contemporary account of the birth survives.

Later biography names his parents as Ariston and Perictione and his siblings as Glaucon, Adeimantus and Potone. Ariston's family claimed descent from the legendary Athenian king Codrus and Perictione's claimed kinship with Solon — ancient genealogical claims, not independently documented pedigrees.

Athens is the usual choice of birthplace, though Diogenes Laertius preserves an alternative tradition that Plato was born on Aegina while his father was there as a settler.

Why the year is written 428/427

428/427 BCE is the most widely used estimate, reconstructed rather than recorded. The chronology of Apollodorus of Athens is one ancient source behind the traditional date, though it produces tensions when combined with other reported ages and dates.

Diogenes' own statements do not agree internally: his reports of Plato's age at death, of the year Pericles died, and of Plato being 28 when Socrates died generate different birth years. Proposed chronologies include 430/429, 428/427 and 424/423 BCE.

Later tradition assigned Plato the seventh of Thargelion, a birthday shared with Apollo — a late, religiously suggestive tradition rather than an independently corroborated birthday.

How much the ancient biography can carry

Ancient biographical material about Plato is late and frequently anecdotal, which is why the year, the birthplace and even the name all remain dependent on later traditions.

Even the name is contested. One ancient tradition holds that "Plato" replaced an original "Aristocles", and reference works do not treat the question as closed — the IEP says his given name was apparently Aristocles.

Nothing public is recorded as following from the birth itself. His older brothers Glaucon and Adeimantus both later became speakers in the Republic.

Sources

Researched 23 Aug 2026 7 sources 2 audit passes Date disputed

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date disputed. Sources disagree; the research places it at ~-428/-427.

What the sources leave uncertain

428/427 BCE is the most widely used estimate, but proposed dates also include 430/429 and 424/423 BCE.
Diogenes’ statements do not agree internally: his reports about Plato’s age at death, the year Pericles died and Plato being 28 when Socrates died generate different birth years.
Athens is usually preferred as the birthplace, but Aegina appears in ancient tradition.
The seventh of Thargelion is a traditional festival-style date, not an independently corroborated birthday.