Wednesday, April 23, 2014

The ship of Theseus

From Wikipedia :

The ship of Theseus, also known as Theseus's paradox, is a thought experiment that raises the question of whether an object which has had all its components replaced remains fundamentally the same object. The paradox is most notably recorded by Plutarch in Life of Theseus from the late 1st century. Plutarch asked whether a ship which was restored by replacing each and every one of its wooden parts, remained the same ship.

The paradox was first raised in Greek legend as reported by Plutarch,


—Plutarch, Theseus2
Plutarch thus questions whether the ship would remain the same if it were entirely replaced, piece by piece. Centuries later, the philosopher Thomas Hobbes introduced a further puzzle, wondering: what would happen if the original planks were gathered up after they were replaced, and used to build a second ship.3 Which ship, if either, is the original Ship of Theseus?

Another early variation involves a scenario in which Socrates and Plato exchange the parts of their carriages one by one until, finally, Socrates's carriage is made up of all the parts of Plato's original carriage and vice versa. The question is presented if or when they exchanged their carriages.