The Ship of Theseus Thought Experiment — Can You Solve It?

Can you solve the famous philosophical thought experiment of the Ship of Theseus?

There was a glorious warship that belonged to Theseus, the legendary founder of Athens, that the citizens of Athens felt they needed to preserve. Once in awhile, a plank of wood would need to be replaced with a fresh one so the ship was in good order.

If the citizens eventually replaced the entire ship with new planks of wood, would it be the same ship of Theseus? What if the citizens built a new ship out of the old planks of wood, exactly the same as the original ship of Theseus? Would this new ship actually be the real ship of Theseus?

This is an ontological philosophical problem which means it deals with the nature of being. Here we’re asking what’s real and what’s not in the world.

The ship of Theseus issue is still being debated today in many different forms.

Take, for example, the chair I’m writing this article on. It seems like a real thing, obviously, but we know that it’s really just a collection of atoms arranged in a certain way. So, is the chair not a real thing as its true nature is just atoms and quarks?

In a past article, I’ve talked about the theory of ontological naturalism which states that everything we know is just nature and natural laws.

That means there isn’t any evidence or reason to believe in supernatural things like a God or something like Plato’s realm of ideas where the perfect Ship of Theseus or the perfect chair resides. There’s just nature and that’s it.

We have no reason not to believe naturalism isn’t true at this time as I wrote about and there certainly seems to be things like people, chairs, and ships, right?

So how do we explain the logical predicament of the ship of Theseus? Is the ship of Theseus really just atoms and there is no ship at all? Are we just atoms and there’s no such thing as ‘us’?

What is Emergence?

To answer this question, we need to talk about the idea of emergence.

Emergence is what occurs when we observe something that seems to have properties its parts do not have on their own.

If you’ve ever looked up in the sky and seen a flock of birds, you probably noticed that it looks kind of like a dark cloud with a mind of its own, shifting and moving about. But, upon further analysis, you would see it’s just individual birds, and each bird’s behavior affects the bird next to it.

Similarly, a hurricane appears as a thing unto itself, but upon further analysis it is really just water, wind, and temperature interacting with one another.

That’s emergence. We can say the flock of birds is an emergent phenomenon composed of smaller objects, the birds.

In fact, everything we notice can be described in terms of emergence. People, nations, cellphones, organs, rainforests. These are all things that are composed of smaller things that have different properties than the sum of their parts.

And there are different stories we can tell about each part of the emergent phenomenon.

For example, we can say that the flock of birds is moving in our direction. We can drill down an emergent layer and talk about a specific bird in the flock. “Oh, that bird with the off-colored features appears to be stuck in the middle.” We can drill down even more and talk about the cells and tissues within that specific bird. We can even talk about the individual atoms in the cells, and so on.

Each of these layers has its own ontology, or own set of rules, vocabularies, and ways of interacting. The layers can be very different from the other parts while at the same time all being true. All still falling under the natural laws of the world, just described differently.

Now, to be a little more specific, researchers divide emergence into two categories: weak emergence and strong emergence.

Weak emergence is when the emergent phenomenon can be broken down into smaller parts that describe it. In other words, if we gathered all the data about these smaller parts, we could simulate the larger thing they make up.

Strong emergence means the emergence phenomena is not irreducible to its parts. When small parts come together, we should look for something brand-new in its behavior that the smaller parts can’t ever explain.

Now, there’s a lot of debate about whether or not strong emergence is really a thing, as it seems to almost be describing magic. We put a bunch of stuff together and get something so totally different that it doesn’t make sense how combining those things could even give rise to it.

According to naturalism, everything should be reducible to its smaller parts or physics, as we know it, wouldn’t work properly. That includes something as complicated as attempting to describe how human societies work in terms of weak emergence.

But we may not even need to worry about whether strong emergence is a thing or not, as you’ll see in a second.

Poetic Naturalism — One Way of Describing Reality

Okay, so back to our Ship of Theseus Issue.

Philosophers have different ways of trying to explain what’s real and what isn’t. At one extreme, there are philosophers who believe in something called ontological reductionism. Basically, they think everything is just a sum of a smaller thing until we reach a point where we can’t go any further.

For example, a ship is just wood, which is just atoms, which are just made up of quarks, and so on. Physicists use the term ‘wave function’ to describe and talk about reality on the smallest scales we know. So, in that case, everything is just a wave function? That would mean the ship of Theseus is not real and just a wave function.

On the other side of the spectrum, we have people who fall into this strong emergence line of thought and believe that we need to break the rules of physics and ontological naturalism for anything to make sense and be real.

So in this case the Ship of Theseus is a real thing that violates and somehow violates over a century of scientific study.

However, there’s an idea in the middle of this called poetic naturalism that comes from physicist Sean Carroll that solves this riddle more coherently in my opinion.

Poetic naturalism states that something is real if it plays a particular part that, as far as we can tell, provides us an accurate description of the world within its domain of applicability. In other words, there are a variety of ways to talk about the world on different levels of emergence, using language dependent upon the level of emergence we’re talking about.

That may sound confusing but I’ll explain.

According to poetic naturalism, atoms are real, wood is real, ships are real, people are real, and societies are real. There are just different ways of talking about each one and different levels of emergence.

One layer of emergence is the atoms, another layer is the wood, another is the people on it. Each has it’s on ontology or way of talking about it.

What’s not real then?

Things that aren’t real don’t play a part in an accurate description of the world or violate the natural laws. As Carroll puts it, if you’re in a desert and you see a lush oasis, chances are that it isn’t real and is just something in your mind. But if you approach it and find it is really there and you put your hand in to drink some water, that’s real even though the water is just an emergent way of talking about the hydrogen atoms in it.

Simply put, there’s only one world, but multiple ways of talking about it, providing the most useful way of describing the natural world we have.

When we are using poetic naturalism to describe reality, we just have to make sure we don’t mix up the behaviors and vocabulary of each level or emergence. For example, we can talk about a person as being alive or dead, but not the atoms of the person. Alive and dead are not part of our best theory of talking about subatomic particles; therefore, it doesn’t make sense.

Solving the Ship of Theseus Experiment

Let’s apply the idea of poetic naturalism to the ship of Theseus issue.

So, we can say the ship of Theseus is a real thing on the emergent level. It’s a concept we made up to help communicate about that particular structure in nature and tell stories about it. But is the rebuilt ship the true ship of Theseus? Well, it’s up to each of us to decide the way we want to talk and think about it.

Of course, when we start talking about it in terms of different planks of wood, or on a lower level, the atoms in it, this ship of Theseus term doesn’t make sense at that level, so we don’t need to incorporate it.

Now, we don’t have to say the ship of Theseus is just atoms and as many ontological reductionists would way.

Nor do we have to say the ship of Theseus is a real objective thing — a perfect idea something Plato would think about, if you will — separate from the known laws of nature and physical planks that make it up like the strong emergence people may suggest that violates the natural laws.

Hopefully, that wasn’t too hard to follow! Let me know what you think of this solution and poetic naturalism.

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