The Ship of Theseus - An Identity ParadoxWatch
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?
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.
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?
It does matter.
It does not matter. Only the water defines a river.
Water is not important in identity.
No, water is important still.
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?
Think about it.
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?
Are they still the same person as before?
So, what makes an object what it is?
What defines the identity of an object?
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.
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.
There's is no right answer.
I suppose everything is what we make of it, perhaps the remaining design in that ship is enough to preserve its identity.
i guess all you can say is "ask Theseus".... if he says it is his ship then it is.
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.