The Ship of Theseus is a philosophical thought experiment that asks whether an object is the same object after all of its original parts have been replaced. The experiment is also known as Theseus's Paradox. The thought experiment was proposed by the ancient Greek writer Plutarch in Life of Theseus. It involves a ship that was originally made of wood, but over time, each piece of the ship is replaced with a metal part. The question is whether the ship that remains after all the replacements is the same ship as the original ship.