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Tuesday, February 21, 2023

The Ship and its Cargo -- a different answer to the thought puzzle about identity

Someone proposed this thought puzzle (it is not Theseus' ship [Wiki] as will be explained after this puzzle): 

Odysseus sailed from Troy, and it took ten, long years. On the way, due to attacks of animals, sirens, insects, waves, storms, shipwrecks etc. the ship fell apart, piece by piece. As parts failed, they replaced them, one by one. When they arrived home, the ship had every piece replaced. Was the ship that left Troy the same as the one that arrived? 

[Assume this story of the ship is the more accurate one for the thought puzzle.]

It took me a day to think of a good answer for this, and it differs from other answers I've seen in the above Theseus puzzle.

The answer is yes and no.

First, each piece of wood is an individual with strengths and failings as it falls apart, the other parts of the ship have adjusted to this part's strengths and weaknesses, so that the ship's whole integrity is dependent on each part. So when a part fails and is replaced with a new part with strengths and weaknesses, the whole ship had adjusted to the old part and will treat the new part as if it were the old part. The new part has its own identity, but is also being called upon to play a new part. The ship adjusts to the new part's strengths and weaknesses.

This is not unlike a traffic slow down where the accident may be long gone, but the slow down remains. An echo of the old ship always remains. Yet, yes, there are new parts here, flowing through. 

A ship is not a ship without its contents, and in this case the crew create the ship's meaning, it's shipness. How the contents react to the ship--their habits of walking in the same places--creates unique wear, whether the parts are new or old.

If you transfer the contents to a new ship, built by the same people to same specifications, is that the same ship? No. Again, each block of wood employed is different. Also, to borrow from the cognitive-science explanation, the crew would not recognize it as the same.

This applies to humans, who are said to have replaced enough cells in seven years to be a completely new person. Are we still ourselves?

The ship metaphor translates well. Each cell replaced is an individual, yet is shaped by his neighbors. The other cells will be accustomed to certain ways of responding. So yes, sort of a new person?

But it will keep the same cargo, the same contents everywhere it goes--memories, desires, hopes. But these do shift. Is Odysseus the same Odysseus who left Troy? In a sense, yes. His dog recognizes him. He still wants to be with his wife. In a sense, no, his wife does not immediately recognize him. How could he have lived through all he's lived through be the same? But yet some of the same bilge and bilge rats linger.


Interesting thought experiment: If someone murders someone, are they still a murderer seven years later? I suspect most will have only one answer for that.


Despite a similar scenario--replacing parts until the new has all new parts--the Theseus ship is different. Quite different [Wiki]:

Theseus, the mythical Greek founder-king of 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 commemorated this legend by taking the ship on a pilgrimage to Delos to honor Apollo. A question was raised by ancient philosophers: After several centuries of maintenance, if each individual part of the Ship of Theseus was replaced, one at a time, was it still the same ship? 

Here the answer is simply: No and Maybe, depending.

The difference here is the use. Odysseus was the one and only captain/owner. Theseus, meanwhile, has passed on, leaving the ship to descendants whose memory may or may not hold the original crew. A whole different metaphor is at play. The ship is now used for a wholly different purpose: commemoration. After the original passengers have all died and cannot pass on memories of this time, no crew remains to assign it the original meaning. 

It seems likely the scenario arose after a repair and someone, tired of the memorial, wants to know why they bothered remembering this ancient history and raised this thought problem in order to get out of having to repeat this stupid boat trip year every year.

This seems a very human reaction. In the Hebrew Bible--Exodus--the slaves who escape Egypt are supposed to commemorate this escape with a song, but soon they complain about how much better they had as slaves. Memory is short. Also, a very human reaction.

But someone somewhere has recorded the events, and if they did a good enough job, the ship can come close to having its original shipness.


Hobbes apparently proposed that if someone saved all the discarded parts, would that be the ship? 

Interesting thought experiment, but no. The parts are all rotted and broken although it would be a kind of cool memorial.

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