# The Ship of Theseus - An Identity Paradox

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#1
This is a great problem to think about.

What makes an object what it is?

SCENARIO 1 - The Ship of Theseus

There is a grand and ancient ship called the Ship of Theseus. But it's nearing the end of its life and its components are rotten and need replacing. As old planks from the ship decay they are replaced, one by one, over a long time period by new and strong timber until one day the entire ship contains none of its original material. The ship continues to sail during and after this time.

Is this still the Ship of Theseus?

Yes
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Does that mean the story behind the ship is more important than the materials from which it is built?
No
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At what point did it stop becoming the Ship of Theseus? Was it when the first plank of wood was replaced? Was it when the last was replaced? Or was it when less than 50% of the original materials remained?

SCENARIO 2 - The Old Ship

The decaying materials removed from the original Ship of Theseus are gathered up and stored. After the entire ship had been refreshed, a second ship is constructed out of the recovered material as an exact replica of the original.

Which ship is the Ship of Theseus?

The refreshed ship from scenario 1.
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Then how can a ship made out of all the original parts of the Ship of Theseus and designed in the same way not be the Ship of Theseus?
The reconstructed ship
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What does this make the other ship then?
Both are the Ship of Theseus
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How can a single object exist in two places at once? Surely only one can be the real ship?
Neither are the ship.
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So where has the Ship of Theseus gone? All the parts are still there in one ship, and the other ship still sails and carries on the legacy. Should neither be called the Ship of Theseus?

SCENARIO 3 - The River

Now imagine a river. With every passing moment the water in the river refreshes and changes. Like the Ship of Theseus, the river's water is replaced as the old water flows out and new water flows in.

Does this change who the river is?

Yes
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Then does the location of the river not matter at all?

It does matter.
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If the river erodes away at the land and gradually changes its location, shape and size, does that change who the river is? Or does a river simply exist for all time?

It does not matter. Only the water defines a river.

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What happens to the identity the water carries when it leaves the river, such as when it flows into the sea? Does it forget who it is?
No
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Does that mean the water in the river is not part of the river's identity?

Water is not important in identity.
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Then surely a river without water is still a river?

No, water is important still.
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How can the water be part of the river's identity if it keeps changing? What makes a river a river?

SCENARIO 4 - The Human

A human grows old and gradually their organs fail and are replaced, one by one, by mechanical contraptions to keep the human alive. Eventually, all parts of the human except the brain are replaced.

Are they still human?

Yes
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Why? Are their memories important? Does their soul exist in their mind? What even is a soul? Are they the same person as before?
No
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Then at what point did the human stop being human. Was it when their first organ was replaced? Was it when only their brain was left? Or was it when 50% of them had been replaced.
Is replacing flesh with metal really so different to replacing flesh with new flesh - the process of natural healing and growth in organisms?

One day the brain is replaced by an advanced AI, capable of imitating the behaviour of the former human perfectly and it possesses all their memories.

They now have none of their original body remaining.

Are they still human?

Yes
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Can you be human without flesh and bone?

Are they still the same person as before?
No
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At what stage did they stop being human? Why is it that a machine simulating a human perfectly cannot be considered to be human? What makes a human a human?

CLOSING UP

So, what makes an object what it is?

Function?
Materials?
Capability?
Background?

What defines the identity of an object?
0
5 years ago
#2
This is my first venture into the Philosophy forum and damn, that was deep

I think all four can define the identity of an object, but not all 4 are necessary to do so.

I don't think the reconstructed ship is the same ship, as no original parts remain. It is a brand new ship that's been slowly built. It's Mark II of the original ship.

In Scenario 2, I believe it is the same ship. It's like in Monster's Inc, where they shred Boo's door, but then all the pieces are put back together. It's still Boo's door. (that was a really bad analogy )

In Scenario 3, I'm of the belief that it is the location of the river, rather than it's contents that define it's identity.

In Scenario 4, the being is still human as they still feel and act like a human, and still have a human brain. However, if I was to build a robot, grow and put in a human brain, it wouldnt be human in my eyes as I have added the brain to the robot. It wasn't originally there. That is why I think they are no longer human if the being has none of it's original flesh.
1
5 years ago
#3
Taken you've been reading some Wittgenstein?

w.r.t. to scenario 1 & 2, you have to decide exactly what sort of label "the ship of theseus" is exactly.

For example if you take a reductionist (or physical) view, the ship of thesus is simply the sum of the individual pieces of wood & other materials that Thesus travelled on. And so once you replace the materials, it is is no longer the ship of Theseus.

However, if you take a holistic (or metaphysical) view the "ship of theseus" entails a definition greater than merely the sum of its parts, and so you can renew the individual parts and still retain the identity as the ship of theseus.

0
5 years ago
#4
He just lost his legal control of the status of the ship. Because he's a human and he's dead. So now the ship doesn't belong to him.
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0
5 years ago
#5
Might as well ask if we are the same person we were yesterday, last year or as a baby in arms. We do shed a lof cells along the way, for starters.

I suppose everything is what we make of it, perhaps the remaining design in that ship is enough to preserve its identity.
0
5 years ago
#6

i guess all you can say is "ask Theseus".... if he says it is his ship then it is.
0
5 years ago
#7
Ill go straight for the human question. Its a pretty straight forward, but requires a little bit of a distinction between the identity as identified by the person, and that by others external to the self.

Simply put, replacing the entire brain loses the identity of the self. What is important is allowing the new part of the brain before removing the part it replaces. The speed you do this will determine the fluidity of the transition.
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