From a scientific point of view Aliens explanation is in deed compelling but it is just one possible approach. Like Alien, I think that the puzzle makes a basic false premise.

In my opinion an object doesn't have an „identity“. For me, identity is something that exists on a psychological meta-level and implies the presence of consciousness. Or, in other words, the ability to reflect on oneself.

A ship or any object can be an entity. Call me a nitpicker but for this puzzel and my approach on it it's essential. An object or entity constists of material and form. And at this point I can go with Aliens explanation. Matter (I always use the word material) is not real.

The world we live in, our whole understanding of the world, with all it's objects and subjects is based on social agreement. At a certain point millions of years ago, people started to name things and by doing this an idea of what a single thing „is“ became part of common and accepted knowledge within a community. And it became „reality“. So in fact our daily reality is nothing more than a social construct. And sometimes we can watch it fail. Especially when different cultural habits collide. Like e.g. in our hemisphere black is the color of grief, in Asia it is often white.

The agreement, that a ship is a „ship“ is a social one. Bringing certain kinds of material (wood, metal) into a certain kind of structure/form, makes them a ship.

End of the excursus on Social Construtivism (I recommend „The Tree of Knowledge“ by Maturana and Varela)

If we now change to the perspective of the creator of the ship, the „memory or perhaps (...) the story we tell about the thing itself“ becomes relevant from a psychological point of view. Many artists say that a part of themselves goes into a piece of art they create. That the act of creation is self-revealing, maybe cathartic. So, I am pretty sure, that most artists would say, that a part of themselves, a part of their identity, has flowed into the artwork. If we now take the Mona Lisa and scrape every little piece of the painting off the canvas and “reassemble” every little piece into a painting again, I am absolutely sure that Leonardo would totally disagree that it is still the same paintig.

In my opinion there is no easy or single answer to Theseus's puzzle. But it was fun to think about it. I liked it a lot. Thank's for giving me a reason to deal with this;-)

@Alien

Fascinating stuff! Your explanation is compelling. I’ve never studied these particular topics, but I think what you said makes sense.

When I‘ve given my thoughts on the Ship of Theseus, I’m told that my answers drift toward the belief in psychological continuity. The concept is essentially a way of perceiving identity or in this case, defining what we would consider the “ship.”

Going along with what Alien said about ourselves constantly being replaced by new cells, we still generally consider ourselves the same person because “psychologically” we are still “continuing” from past, to present, and to the future with memories that are still building on top of each other. It’s like the whirlpool metaphor that Alien gave. The molecules change, but the happening that is the whirlpool is still seen as just one whirlpool.

Following from my tendency toward psychological continuity, I’m inclined to believe that the ship that continues the journey is the one that has the “soul,” even if it is replaced. If I were to collect all of the replaced parts and rebuild the ship as closely as one could, I wouldn’t consider it the original. I would consider it a ship made of my current ship’s old parts. The moment that each part broke off from the ship, it ceased to be considered the ship because the soul isn’t in the individual planks in my mind. It is in the way that humans generally have been designed to view and perceive identity.

This is still a theory at the end of the day. I haven’t had a chance to reply or do much boggle stuff as of late so I thought I’d at least drop in my thoughts

Ummm, but scrabble would be cool, if that ever happens. Tom Robbins is a genius author about the spirit of inanimate objects. But, I am not into giving anyone a headache… And at a point, dissecting gets ridiculous. although somewhat interesting to see how the spirit of matter can be interpreted. I swear, I have dresses that have souls, just saying…

Let’s make him do this more, with other complicated stuff.

We should make a list. Lists are great.

This is why you never date a physics major….

@Dom :

If you think replacing the planks means it is a different ship, then at what point is it no longer the same ship? After you replace one plank? If not, how many planks to you have to replace for it to be a different ship? Half? But then is it the same ship if you replace half the planks minus one, then when you replace the next plank it becomes another ship?

Every cell in your body is replaced something like every 12 years. So are you no longer you?

This puzzle makes a basic false premise. That the world is made of material. The materialist view sees matter as being what the world is made of. But matter is not real. It is just an idea that people invented. Atom's are basically empty space. Quantum mechanics says that actually it is all waves. Quantum field theory say no, it is actually all fields. In fact there is no such thing as things. We think of the world that way, because our language uses verbs and nouns. Nouns are things that are static, and nouns do things. But in fact nothing is static, and everything is just a happening. We don't tend to think of a person or a boat as a happening, because they change very slowly.

Think of a whirlpool in a lake. The molecules in the whirlpool are constantly changing, but the whirlpool is a happening that persists. You can identify it by it's pattern. The pattern persists for a certain amount of time. In the same way, all of the atoms in your body change over time, but the pattern that is you persists.

So, if you replace one plank at a time, those planks become the boat. If you rebuild a boat out of the same planks that were replaced, then it is a new boat.

You might say, well aren't both the boats the same boat, since they are a copy? Well in the case of boat, that may be true. But it turns out that it is impossible to make an exact copy of something without destroying the original object. It is called "The No Cloning Theorem". So if you tried to copy a person, you couldn't do it. You could make something simliar. But not an exact copy. You would always know which was the orginal.

Wow, we're getting philosophical.

Rational part: It's not really a copy. Because it's about the replacement of all the single parts and not building a second ship next to the first one. It's more like a swap.

Identity for me implies that a conscious is involved. Which an object doesn't have.

Irrational part: But I am a big supporter of the idea that things/objects we deeply love and care for have a soul (stuffed animals e.g.). As if a little part our love flows into this object and, in a sense, enlivens it (metaphorically speaking). If I replace all the parts of that object then I rob it of its soul.

Anyways: It's not the same ship. It's a reconstruction.

Lolol, I know eh? I’ve been stuck in a loop about this one. I can’t decide how I feel about it.

It is not the same ship but a ship built the on the same design as the old ship. Original versus copy. Old but new again. Don't make my brain hurt before I am getting ready to sleep....