12.3 The Ship of Theseus

We all have seen this quote written or used in many places - Change is the only constant in Life.

It is attributed to the Greek Philosopher Heraclitus. It is popular because it is true in our perceived world. Though it doesn’t call out the fact that things get more disorderly with time, it says that things change with time. We see ourselves get old, cities getting gentrified, weather changing every month, politicians changing their opinions every week and so on. Some changes are rapid while the others are slow. If you look at the planet earth from the time it was created around 4.5 billion years ago, it would look unrecognisable.

This leads us to an interesting philosophical problem, popularly named the Ship of Theseus problem. This is how the story goes - An ancient Greek hero named Theseus sailed in a ship. The people of Greece preserved this ship as a memorial. The ship was made of wood that rots with time. Whenever a piece of wood rotted, they replaced it with a new piece. After many years, all the wood from the original ship got replaced by new pieces. At that point, was it still the ship of Theseus?

Many of us feel sentimental towards things - The ones given to us by the loved ones or the ones which marked important occasions in our lives, like our wedding clothes. If parts of these things got damaged and you had to change these parts, do you still feel that it has the same sentimental value? Some may say yes, some may not.

This problem hits the root of our concept of a unique identity. There is a widespread myth that all the cells in your body get replaced in seven years. For now, let us assume that this is true. If you met your friend who you last saw about ten years back, was it still the same person you are seeing? You may say, “Yes, he has changed a lot. But he is still George.”

This is particularly a problem for physicalism because according to them the physical world is all that exists and if this world keeps changing, it is hard to define unique identities across time. A dualist, idealist or a theist may say that the soul or mind is outside of the physical world, which is immutable and hence maintains the identity.

The truth is a bit complex. There are some neurons in the brain, some cells in the eye lens and heart which stay with us forever and aren’t replaced. So one may argue that there are parts of our body which stay the same throughout our lives. But these neurons and cells do undergo structural changes themselves. Can we still call them the same?

There have been multiple attempts at defining the identity of individuals philosophically and scientifically, each with their own issues. Some are based on physical continuity - George is the person identifying with the body that was born in Washington at address X, grew up there and moved to Chicago for university and so on. While this could work theoretically, it is practically hard for someone to keep track of George all the time. Some are based on memories - George is a person who has all the memories of his own life. If George has an accident and forgot all about his life, is he not the same George anymore?

There are more interesting thought experiments in this structure. There was a movie named Dual released in 2022 starring Karen Gillan and Aaron Paul. It didn’t do well with the audience, as you may have seen from the ratings. It does have an interesting premise. In a fictional future world where human cloning is a technology that is allowed and is also strictly regulated, people who are going to die due to terminal illness are allowed to create their own clones for their loved ones. The protagonist does so after she receives a terminal diagnosis. But days after the clone is created, she recovers from her terminal illness. The future government was diligent enough to foresee situations like this and had written laws to handle them. It’s simple really. The original and the clone duel to death.

That probably has already hinted you at the problem. I would like to discuss a few variants of this.

Imagine a Transporter in Spain that deconstructs you, takes every atom in your body, beams them to Norway where you are assembled again. If you go through with this, is the person in Norway the same as the person who was in Spain before the transportation happened?

Imagine another Transporter in Spain that deconstructs you, but instead of beaming those same atoms, collects the exact types of atoms in Norway and builds the exact configuration about your body. For every hydrogen, carbon, oxygen and other atoms which were deconstructed in Spain, it takes the exact atoms in Norway to construct you again in the same structure. If you go through with this, is the person in Norway the same as the person who was in Spain before the transportation happened?

Now imagine a cloning machine that does the same as (2) but doesn’t really deconstruct you and instead creates a copy of you. Are the two people in Spain and Norway the same?

Depending on your answer, there are a lot of moral and legal implications. In the cloning situation, for example, who owns the original person’s properties? One can see why the fictional government in the movie Dual wanted them to fight it out. What about relationships? Which of the clones is your husband or wife? While it could indeed be convenient in some situations, it is overall hard to figure out the logistics of such a relationship.

A physicalist could just put up his hand and say that the concept of unique identity is an illusion in the world of physicalism. If the world does reach a situation where we clone or transport people like this, we just need to come up with a new moral and legal framework to work around the problems. And it is a totally reasonable answer.

A dualist, an idealist or a theist on the other hand can either say that the clone is a different person, the clone is not even a human or that they don’t know. Either way, these philosophies don’t rely on empirical verification on matters of mind, like physicalism does. They claim that the mind or soul is an entity outside of the physical world. Claiming that the clone is the same person would be difficult to explain as it leads to questions around how this single mental entity could attach to multiple physical bodies just when the body is cloned but not otherwise.

Either way, this is an interesting puzzle to ponder over, don’t you think?