The legendary ship of Theseus raises a number of philosophical questions. Right here, we see a Nineteen Twenties illustration of an historical Greek Bireme that has two decks of oars. (Picture credit score: Pictorial Press Ltd / Alamy Inventory Photograph)

As soon as upon a time — a minimum of in line with the traditional Greek author Plutarch — the hero Theseus sailed from Athens, Greece, to the island of Crete, the place he slayed the half-man, half-bull Minotaur earlier than crusing again to rule Athens. 

The wood ship that Theseus sailed on, Plutarch imagined, should have change into a nationwide treasure, and he posed a thought experiment that has fascinated philosophers ever since: If you happen to repaired Theseus’ ship plank by plank in order that no authentic planks remained, is it nonetheless the identical ship? 

“The individuals who’ve been crusing the ship will say, ‘Yeah, it is the identical ship! We have been crusing for years, and we simply preserve fixing it,'” mentioned Michael Rea, director of the Heart for Philosophy of Faith on the College of Notre Dame. 

“However you may think about a collector wanting to place the unique ship within the museum,” Rea informed Dwell Science. “She goes and gathers up all the unique planks, rebuilds them and says, ‘I’ve obtained the ship of Theseus!’ So, the query is, which one is the ship?”

Associated: What’s Occam’s razor?

Variations of the ship of Theseus thought experiment pop up in all places. In Marvel Studios’ “WandaVision,” Imaginative and prescient comes face-to-face with a reproduction self and should work out who’s the actual Imaginative and prescient. In “The Good Place,” Chidi Anagonye lives a whole lot of separate lives and should confront which, if any, represents his actual self. In different eras, individuals have requested if an ax nonetheless counts as George Washington’s ax if each the deal with and the ax head are changed. 

“It seems like only a dumb celebration puzzle, proper?” Rea mentioned. “However you may study so much by considering by way of these puzzles actually rigorously.”

The ship of Theseus thought experiment raises questions concerning the materials composition of objects: Is the ship the sum of its planks, the sum of its crusing historical past or each directly? Can objects made up of different objects even be mentioned to exist? 

To reply these questions, philosophers should cope with conundrums resembling whether or not two issues can occupy the identical place on the similar time, how components relate to an entire and the way to consider the character of time. 

“The Story of Theseus” reveals Theseus’ ship and his killing the minotaur on the heart of the labyrinth.  (Picture credit score: Photograph 12 / Alamy Inventory Photograph)

One reply, Rea mentioned, is to say that solely the planks are actual and the ship “is only a part.” Taken to its logical excessive, this reply, nihilism, implies that solely basic particles exist; objects made up of a number of components are simply an phantasm. 

However maybe ships do exist; in that case, perhaps they’re outlined by their components. In that case, Rea mentioned, “the museum curator is right.” If objects can survive half substitute — our cells, for instance, are continually dying and being changed — then perhaps the ship at sea is the actual ship.

Or perhaps there have been two ships all alongside, generally sharing the identical location. In that case, Rea mentioned, “The phrases ‘ship of Theseus’ had been ambiguous, and that is why now we’re all confused.”

If two objects could be in the identical place on the similar time, it opens up an entire new can of worms — space-time worms, to be actual. 

Maybe the ship of Theseus exists as many overlapping chunks of space-time: The ship within the second when the primary plank was changed, the ship because it was when Theseus walked the decks and the ship’s total existence, from the rising bushes that change into its planks to its afterlife as a philosophical thought downside. 

Associated: The place does the idea of time journey come from?

All of those ships collectively could be mentioned to “perdure.” “If I perdure, I am this four-dimensionally prolonged factor,” Rea mentioned. “Folks began calling these space-time worms.” This view often goes hand-in-hand with the concept the previous and the longer term exist — a philosophical stance referred to as four-dimensionalism — in distinction to presentism, a concept of time through which solely the current second is actual. 

None of this philosophical groundwork, nevertheless, can definitively say which ship is the actual ship.

“I feel that it is extremely attention-grabbing that we’ve this query in any respect,” mentioned Anne Sauka, a thinker on the College of Latvia. The query itself assumes a selected ontology, or concept of being.

She informed Dwell Science that the ship of Theseus puzzle makes essentially the most sense within the context of substance ontology, through which objects are the main target of philosophical curiosity. The choice is a course of ontology, which sees change as extra basically actual than objects. 

Seen that method, the planks, the ships and Theseus himself are usually not static issues however moderately processes which can be at all times shifting. Attempting to assert both ship for Theseus demonstrates an unwillingness to let both ship evolve into one thing new. “The query itself reveals that we’ve an issue with change,” Sauka mentioned. 

The ship of Theseus can be seen as a metaphor for the self: “If we modify, are we a distinct particular person?” Sauka mentioned. In course of ontology, change is the place to begin. “Selfhood is one thing that solely occurs by advantage of change,” she mentioned. Demise “is simply the dissolving of that specific course of that was a secure course of for a time.”