ΦTHALASSAJournal of Philosophy
Philosophers
Historical portrait of Thales

Roman marble head traditionally identified as Thales of Miletus, second century CE · Museo dei Marmi, Palazzo Medici-Riccardi, Florence · photograph Sailko, CC BY-SA 3.0

Ancient · Milesian school

Thales

c. 624–c. 546 BCE

Region: Ionia

The first Greek thinker remembered for explaining nature without appealing to the will of the gods. He held that everything comes from water.

Life

Thales in their own century

Thales lived in Miletus, the wealthiest of the Ionian ports, and was remembered as an engineer, geometer and civic adviser as much as a thinker. Herodotus reports that he foretold the year of a solar eclipse, which modern astronomy places in 585 BCE, and Aristotle preserves a story of him cornering the olive presses one winter to show that a philosopher could grow rich if he cared to.

Miletus traded with Egypt, Lydia and the Levant, and Babylonian records of the heavens and Egyptian land measurement reached it along with the cargo. His questions about the origin and structure of things belong to a city where other people's answers were already in circulation.

Central ideas

01

Water as the origin

He held that everything derives from water: the earliest recorded attempt to trace the variety of the world to a single underlying material.

02

Nature explained from within

Earthquakes happened, on his account, because the earth floats on water, not because a god was angry. The explanation stays inside nature, which is what makes it a new kind of explanation.

03

Geometry as proof

Later tradition credits him with proving geometrical results rather than merely using them, among them that a circle is halved by its diameter.

Criticism & debate

Everything attributed to him comes from writers born long after his death, and Aristotle himself hedges his reports with 'they say'. The eclipse prediction and the geometrical proofs may belong to the legend that gathered around the first name in the tradition.

Influence

Aristotle treated him as the beginning of philosophy, and the Milesian search for a single origin runs on through Anaximander, Anaximenes and the atomists.

How to read them

Begin Thales with the tension between water as the origin and nature explained from within. Read the major works slowly enough to notice how biography, public crisis and method shape the argument rather than treating the thinker as a list of doctrines.

If Thales is right about water as the origin, what habit of judgement would have to change first?