Ship of Theseus
The Ship of Theseus, also known as Theseus's Paradox, is a thought experiment and paradox about whether an object is the same object after having had all of its original components replaced over time, typically one after the other.
This article is about the thought experiment. For the film, see Ship of Theseus (film).
In Greek mythology, Theseus, mythical king and founder of the city Athens, rescued the children of Athens from King Minos after slaying the minotaur and then escaped onto a ship going to Delos. Each year, the Athenians would commemorate this by taking the ship on a pilgrimage to Delos to honour Apollo. A question was raised by ancient philosophers: After several hundreds of years of maintenance, if each individual piece of the Ship of Theseus was replaced, one after the other, was it still the same ship?
In contemporary philosophy, this thought experiment has applications to the philosophical study of identity over time, and has inspired a variety of proposed solutions and concepts in contemporary philosophy of mind concerned with the persistence of personal identity.
Alternative forms[edit]
In Europe, several independent tales and stories feature knives that have had their blades and handles replaced several times but are still used and represent the same knife. France has Jeannot's knife,[11][12] Spain uses Jeannot's knife as a proverb, though it is referred to simply as "the family knife", and Hungary has "Lajos Kossuth's pocket knife". Several variants or alternative statements of the underlying problem are known, including the grandfather's axe[13] and Trigger's broom,[14][15] where an old axe or broom has had both its head and its handle replaced, leaving no original components.
The Tin Woodman, a character in the fictional Land of Oz, was originally a man of flesh and blood, but all his body parts were replaced one by one by metal parts. Nevertheless, he retains his identity.
The ancient Buddhist text Da zhidu lun contains a similar philosophical puzzle: a story of a traveller who encountered two demons in the night. As one demon ripped off all parts of the traveler's body one by one, the other demon replaced them with those of a corpse, and the traveller was confused about who he was.[16]
The French critic and essayist Roland Barthes refers at least twice to a ship that is entirely rebuilt, in the preface to his Essais Critiques (1971) and later in his Roland Barthes par Roland Barthes (1975); in the latter, the persistence of the form of the ship is seen as a key structuralist principle. He calls this ship the Argo, on which Theseus was said to have sailed with Jason; he may have confused the Argo (referred to in passing in Plutarch's Theseus at 19.4) with the ship that sailed from Crete (Theseus, 23.1).
In Japan, the Ise Grand Shrine is rebuilt every twenty years with entirely "new wood". The continuity over the centuries is considered spiritual and comes from the source of the wood, which is harvested from an adjoining forest that is considered sacred.[17][18]