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Ship of Theseus: How to Solve the Ancient Paradox

I accidentally discovered the mythological Ship of Theseus in 2005, while watching MTV Germany. The new show, which I’m sure you’ve never heard of, was called Pimp My Fahrrad (German for bicycle) and was modelled on the popular Pimp My Ride franchise. People would give their shabby bikes to a swag workshop crew in Hamburg, Germany who would then transform them into two-wheeled cruisers. With phat tyres, shiny accessories and all the rest of it.

What worked well with cars seemed a bit silly with bikes. Bikes don’t have too many parts. In the end, there usually wasn’t much left of the original except for some structural bits and pieces. Perhaps the show should’ve been called Pimp My Frame instead. But as the philosophers at MTV probably intended, Pimp My Fahrrad inspired me to grapple with the Ship of Theseus and the age-old question of what makes us humans who we are.

What Is the Ship of Theseus?

The Ship of Theseus, also known as Theseus’ Paradox, is a thought experiment about identity and identity change. The question is whether an object that had all of its parts replaced, does fundamentally remain the same. Theseus was a Greek mythical king and founder of Athens. His most notable deed was slaying the minotaur. The paradox named after his ship dates back as far as 75 ACE when it was first mentioned by the Greek philosopher Plutarch:

The ship wherein Theseus and the youth of Athens returned had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their place, insomuch that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.

Plutarch, Theseus

In its adaptation as a popular thought experiment, the key question is often phrases like this: If all the planks of Theseus’ ship are replaced, is it still the king’s ship? There are two possibilities:

  1. It’s still the ship of Theseus.
  2. It’s no longer Theseus’ ship.

Both choices require a fair bit of explaining. But the second one begs the question: At exactly what stage in the restoration process did it cease to be his ship?

The Problem of Two Identities

It is said that English philosopher Thomas Hobbes took this mind-bending conundrum one step further by introducing the problem of two identities. Imagine Theseus had another ship and he asked to have all its planks replaced in a dock. The shipbuilder, however, doesn’t want to throw the planks out and uses them to build another ship in a second dock. We now have four possibilities:

  1. The ship in the first dock is Theseus’ ship.
  2. The ship in the second dock is the ship of Theseus.
  3. Both are the mythical king’s ship.
  4. None of them is.

You don’t have to be a maritime enthusiast to appreciate the real-life application of this thought experiment. Given that our own identity – who we are and how others perceive us – keeps changing, how should we think about ourselves? Before attempting to solve the identity paradox, we may wonder to what extent a naval thought experiment is suited to answer such a profound question.

What Are Thought Experiments and Why?

Thought experiments are cleverly designed mind puzzles. The Trolley Problem Meme is perhaps one of the best-known ones. They illustrate ethical or philosophical problems which may be impossible to test outside of your imagination. Often posed as paradoxes or dilemmas, thought experiments tend to have clear rules and limited options for action to encourage first-principle thinking. Similar to scientific experiments, they establish a quasi-controlled environment in your mind.

The Purpose of Thought Experiments

Elephant in the Room

However, the point of Theseus’ ship isn’t to ask what else the ship is made of, to nitpick if a second ship could even be built out of the first ship’s planks, or to argue that the entire scenario was unrealistic. The point of a thought experiment is to reduce the complexity of reality. By the same token, they can be rendered useless if they’re designed poorly or just silly. The Buttered Cat Paradox comes to mind.

In saying that, the reality is much more complex and many more factors are involved. What these brain teasers can do is force us to focus on the core of an ethical question. The learnings from such simplifications do not necessarily translate directly to reality. But they can inform our actions and decisions.

Thought experiments can be beneficial beyond any specific philosophical problem. Stories involving moral dilemmas prompt us to reflect on our existence and perhaps even get more comfortable in everyday paradoxical situations. After all, there’s no shortage of those. So it’s not surprising that some variations of the Ship of Theseus thought experiment have emerged in real life and popular culture.

If you get beamed in Star Trek, do you become a copy of yourself and is that copy still you? Given that many of our body’s molecules are replaced every couple of years, who are you, if not the sum of your parts? If first the handle and then the head of my grandfather’s axe is replaced, is it still my granddad’s axe? No matter how you put this question, it seems like you could make a good case for any answer.

Solving the Human Identity Paradox

Even though I had long forgotten about Pimp My Fahrrad, the metaphysical question about our identity remained. Theseus’ ship was a useful thought puzzle to illustrate the seemingly unsolvable paradox of who we are. But none of the options seemed entirely applicable to the human condition. It took more than ten years until I came across a satisfying solution for the paradox posed by Theseus’ ship. In a lecture by psychologist Dr Jordan Peterson. Speaking about facts, stories and values, Peterson concludes:

You’re going from point A to point B and then things fall apart catastrophically and you’re here. […] So you can think: Well, I’m who I was, that would be one kind of identity, I’m the person I thought I was. That blows apart. Then you’re in this terrible place and you think, oh, I’m the sort of person who’s in this terrible place. That’s another form of identify.

And then you can think: I’m not the old person or the person who was in the catastrophe, I’m the new person. But the problem is the new person can fall apart, too.

But then there’s a third way of thinking. This is a better way of thinking. I’m not this, or this, or this, I’m the process by which [the transformation] occurs. I know something, it’s not quite right. It collapses, it causes trouble (the collapse), but I regroup, I learn, I regenerate, I put myself back together and it happens again and it happens again. But each time it happens, maybe, you’re a little wiser, you’re a little more put together.

Jordan B. Peterson, 12 Rules for Life Tour

Identity and the Eternal Now

Who are we in the face of our growth and evolving identity? Peterson conceptualises our identity as a story and suggests that we therefore shouldn’t look at ourselves as fixed states. Rather our identity is the driving force behind the transformation between the states — for the worse or for the better.

I can’t help but notice similarities to the Zen idea of the eternal now. It posits that the past and the future are mere illusions as there is only what happens in the never-ending moment. Paradoxically, this reduces our story to a single state. Reality is experienced only in the present. The past is in your mind only. The future is speculation.

Identity and Personal Responsibility

Peterson’s thoughts are also a nod to personal agency and responsibility. In his reading, identity would be less defined by where who, or what we are at any given moment. But by how we respond to those states. That is the decision we make to transcend our inevitable suffering and manage to grow in spite of it. Again, it would make for a good Zen story in that it’s precisely our insufficiencies that cause transformations through a ceaseless effort to make things better than they are.

What makes this interpretation resonate? It’s no secret that we tend to be harsher on ourselves than on others. After all, we can’t escape the vivid memories of all the worst versions of our past selves. With other people, however, I found that I rather tend to focus on the trajectory they chose for their lives. What I tend to see, respect and admire in people is their story of having been to hell and gotten back out alive. In other words, I see in them the transformative spirit that drives them.

Solving The Ship of Theseus

With that in mind, we should be able to put Theseus’ ship to rest. The thought experiment seems to be less about the rotten planks and more about the act of taking responsibility for replacing them. It’s about the willingness to respond to inadequacies and to let go of insufficiencies, including the ones that gradually built over time. Had the ship not been cared for, the vessel would’ve eventually ceased to exist due to natural decay. Granted, ships don’t have agency, which is why Theseus has to act as a proxy.

Even though in the original story the king has long passed away, we could argue that the wood was replaced in the spirit of preserving his legacy. Arguably, this wouldn’t have happened if Theseus’ deeds hadn’t had such a profound impact on Greek society. The replacement of the rotten planks becomes a symbol of responsible behaviour. The same goes for our shipbuilder. It’s not about where the planks came from. But about his efforts to turn the discarded material into something new and useful. The Ship of Theseus is now his.

Closing Thoughts

I don’t know about you, but I’m quite happy with this solution. It feels comforting that I can remain myself no matter what life will throw at me in the next ten years. And the best thing is, Pimp My Fahrrad can keep its title.