The ship of Theseus

Now the thirty-oared ship, in which Theseus sailed with the youths, and came back safe, was kept by the Athenians up to the time of Demetrius Phalereus.* They constantly removed the decayed part of her timbers, and renewed them with sound wood, so that the ship became an illustration to philosophers of the doctrine of growth and change, as some argued that it remained the same, and others, that it did not remain the same.

*Demetrius of Phaleron, c. 350–280 BCE

Plutarch (c. 46–127)

from The Life of Theseus

trans Aubrey Stewart and George Long


For more on this ancient logical puzzle, see S. Marc Cohen, ‘ Identity, Persistence, and the Ship of Theseus’.


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