Theseus' ship - what is your view?

[pivoxa15]

This is the story:

Theseus is famous in Greek mythology as the slayer of the Minotaur, a half-man, half-bull monster who lived in the Labyrinth in the island of Crete. According to Plutarch, the ship in which Theseus sailed back to Athens was preserved for many generations, its old planks being replaced by new ones as they decayed.

Now suppose that a few hundred years later, all the original parts of the ship had been replaced, one by one, so that none of the original ship remained. Is the preserved ship still Theseus' ship? Or is it a copy? And if the latter, then at what point did it cease to be Theseus' ship?

This problem involves the notion of identity, of what we mean by something being the "same" object. Suppose that we regard the final ship as Theseus' ship. What if all the old planks, nails, etc., had been stored in a warehouse and someone put them back together again. Would there then be two Theseus' ships?

What is your view?

 

[selfAdjoint]

Well, I don't know how Theseus came into this; I learned the problem as great-grandpa's gun. "That's my great-grandpa's gun hanging on the wall. Grandpa replaced the stock, and daddy replaced the lock, and I replaced the barrel, but yep! That's great-grandpa's gun!"

Aristotle had something to say about this. See form and substance.

 

[Orefa]

Try it with a pair of socks. You lose one at the laundromat and replace it with another one you found there. Is it your pair of socks or someone else's? :uhh:

 

[daveb]

This idea is no different than the effects of the passage of time on the human body. As time passes, cells in the body die and are replaced by other cells. Yet, after 7 or so years, when pretty much everything except nerve cells have been replaced, the self is still the self. It is the whole that makes something...something. My body is still my body even after many years, regardless of the fact that "parts" of the body have been replaced.

 

[sameandnot]

this question, pivoxa15, is really more valuable than it is getting credit for, i think. many posts have replied in, what one may consider, a less than genuine or adequate way. i will not attempt to answer this question, directly, but i will suggest a reason why many have "dodged" the question thus far.

i would like to pose one further question, in response:
how can we think ourselves capable of answering a question, about the nature of a thing (which i perceive this question as being... fundamentally), when we are not yet certain of what it is that "i" am?

we are looking to satisfy the nature of theseus' ship as a conceptual or categorical definition. this is not different from the conceptualization that we apply to "i". is asking the question about the nature of theseus' ship any different from asking the question about the self? essentially?

i will say, "no".

further, i propose that the doing, of those who may have "dodged" your question, is an extension of the uncertainty, that those have, in knowing who they are.

again, how can we know what something is, if we do not yet know what "i" am? in light of daveb's reply, what is the "whole"?

this is now a metaphysical inquiry.
to answer the question about the nature of the ship, is to, covertly, make a claim about the nature of the self.

 

[Math Is Hard]

we've had this discussion before:
https://www.physicsforums.com/showthread.php?t=73711

 

[Orefa]

we've had this discussion before:
https://www.physicsforums.com/showthread.php?t=73711

...where Mattius_ finally spoke and got it straight, I see. When you change one sock in your pair, you don't have the same pair of socks anymore. You have part of the original pair, plus something else. It's still a pair of socks, just not the pair you started with. Same for the boat.

 

[pivoxa15]

I think one major problem is language. Our language was invented to help make people's lives easier when living with other people. It was not designed to help us solve all the problems in the universe. Deeper thinkers will find problems in our language such as the notion of identity and many other properties. These confusions are embedded in our language from ancient times. That could be one reason why physics is done in mathematics rather than an ordinary language (that is not to say there aren't any debate in the foundations of mathematics but it is much less than in English).

It is convinent to talk about a whole but sometimes (if you analyse it carefully enough) the notion can break down as we have seen. So the problem is in our language.

 

[Math Is Hard]

I have the Mazda of Theseus. I have replaced virtually everything but the steering wheel. And yet, it's still my same old car.

 

[Orefa]

And yet, it's still my same old car.

It may still belongs to you but it's not the same as when you bought it. It only seems this way when you choose to simplify by disregarding all non-original components.

Years ago I bought a new car from Ford. At the time they provided a lifetime guarantee on all replacement parts on their new vehicles. I figured that if I had every single part serviced and replaced, the whole car would be on a lifetime waranty! I didn't do it of course, but this thread reminds me of this. I would certainly not end up with the car I bought if I had done this. As soon as you change the original, it's no longer the original even if you retain ownership under the law.

 

[sameandnot]

When you change one sock in your pair, you don't have the same pair of socks anymore. You have part of the original pair, plus something else. It's still a pair of socks, just not the pair you started with. Same for the boat.

ever think that there's one pair of socks? or, that there's one boat? ... that there's one self?

 

[Math Is Hard]

It may still belongs to you but it's not the same as when you bought it. It only seems this way when you choose to simplify by disregarding all non-original components.
Years ago I bought a new car from Ford. At the time they provided a lifetime guarantee on all replacement parts on their new vehicles. I figured that if I had every single part serviced and replaced, the whole car would be on a lifetime waranty! I didn't do it of course, but this thread reminds me of this. I would certainly not end up with the car I bought if I had done this. As soon as you change the original, it's no longer the original even if you retain ownership under the law.

I love your thinking, Orefa. And your clear examples. You are an astute logician.

 

[mrj]

Re: Form and Substance and 'sameness.'
How about say, a corporation? After so many years, let's say not only
has there been a complete turn-over of employees, but let's say all the original assests have been sold or traded for a completely different set of assests. It's still ''formally' the same corporation but it is now 'substantially' different.

mrj

 

[Treadstone 71]

The least workable definition, although the most sound, is that each time there is any change to the ship, it becomes something different. So yes, a dent somewhere, and it's not the same ship anymore.

Though this seems unreasonable, since if an atom that is part of the ship decays, or even loses an electron, it is technically something else.

 

[Orefa]

ever think that there's one pair of socks? or, that there's one boat? ... that there's one self?

Not really, not really, and yes of course; why do you ask?

I love your thinking, Orefa.

Thank you!

How about say, a corporation?

Same thing. But you have to remember that a corporation is an entity defined by legal documents, not by its assets. As such, it only changes when the legal documents that define it change.

Though this seems unreasonable, since if an atom that is part of the ship decays, or even loses an electron, it is technically something else.

It is quite reasonable. Everything that exists exists as a result of the transformation of previously existing elements. Nothing is created, nothing is lost, all is transformed. When does a wooden plank become a table? When it undergoes enough changes to fit a new definition. It may be the "same" piece of wood but it ceases to be a plank. Eventually the table ceases to be a table too because it becomes firewood instead, then smoke and ashes... The only item I can think of that maintains its identity is the universe itself since by definition it is all that exists. But since all its parts change constantly then each one can only have a precise identity at a precice moment in time. For practical reasons though, we commonly loosen our understanding of identity so we don't spend all our time tracking atoms.

 

[pivoxa15]

I have the Mazda of Theseus. I have replaced virtually everything but the steering wheel. And yet, it's still my same old car.

Suppose someone was to assemble a car from all the old parts of the original Mazda. So you would have a car that is exactly the same as your old Mazda except for the steering wheel and some minor parts.

Now you have 2 Mazdas. One with only the original steering wheel and most of the remaining parts different to the original car. The other Mazda has all your old parts except a new steering wheel and some other new minor parts. Which Mazda do you cliam is your orignal car now?

 

[Math Is Hard]

Suppose someone was to assemble a car from all the old parts of the original Mazda. So you would have a car that is exactly the same as your old Mazda except for the steering wheel and some minor parts.
Now you have 2 Mazdas. One with only the original steering wheel and most of the remaining parts different to the original car. The other Mazda has all your old parts except a new steering wheel and some other new minor parts. Which Mazda do you cliam is your orignal car now?

The one possessing a VIN number that matches my title.

 

[Orefa]

Which Mazda do you cliam is your orignal car now?

Neither. The original car was made of all its original parts so neither of these two cars qualifies.

Ownership is a different (legal) matter.

 

[sameandnot]

we have posts (so far) that conceive the ship as composed of atoms. this view is not different from the view where the ship is conceived as being composed of planks of wood and other parts. the point is the same in both views: that all "things" are composed of various parts which, when altered, alters the "object" in such a way as to only be conceived of as a continually existing entity in a very abstract way.

we are currently discussing the nature of this "abstract" notion.

which brings me precisely to my previous (now deleted... lol) post. only now, i am careful to avoid great depth... or any at all, really. so i will give an observation, and be done.

we are really talking about whether there are entities that have "continual existence", through time; whether one conceptual entity can be said to exist objectively (as an "object"), independently, from one moment to the next.

this is the fundamental point of this discussion, i think.

i will say:
some thing only seems to exist independently, in space and time.
because some thing exists in space, it is subject to time and change.
if something is absolutely subject to time and change, in respect to spatiality, then it becomes impossible to say, exactly where one thing "begins" and "ends" and where another "begins" and "ends".

this is elementary for some, but requires deep contemplation for most.

oh well, "what is to be will be".

 

[Math Is Hard]

Neither. The original car was made of all its original parts so neither of these two cars qualifies.
Ownership is a different (legal) matter.

yup. Right you are. Wrong am I.

 

[pivoxa15]

we have posts (so far) that conceive the ship as composed of atoms. this view is not different from the view where the ship is conceived as being composed of planks of wood and other parts. the point is the same in both views: that all "things" are composed of various parts which, when altered, alters the "object" in such a way as to only be conceived of as a continually existing entity in a very abstract way.

we are currently discussing the nature of this "abstract" notion.

which brings me precisely to my previous (now deleted... lol) post. only now, i am careful to avoid great depth... or any at all, really. so i will give an observation, and be done.

we are really talking about whether there are entities that have "continual existence", through time; whether one conceptual entity can be said to exist objectively (as an "object"), independently, from one moment to the next.

this is the fundamental point of this discussion, i think.

i will say:
some thing only seems to exist independently, in space and time.
because some thing exists in space, it is subject to time and change.
if something is absolutely subject to time and change, in respect to spatiality, then it becomes impossible to say, exactly where one thing "begins" and "ends" and where another "begins" and "ends".

this is elementary for some, but requires deep contemplation for most.

oh well, "what is to be will be".

So entities like pie (in mathematics) can be confidently said to possesses an identity which will never change. Since if you change one of its numbers it will not be pie but something else. So you either have pie or you don't. There is no inbetween. However, physical objects are not so certain at all. We can go down to the molecular level and if that is not enough, I am sure there are deeper levels such as all the way to Planck's length. None of our detectors can pick out change in quark arrangements in macroscopic matter but they are surely going on all the time. So even if we have a car that has not been tampered with, it is pepetually changing. The context in which we apply a word is important. We can easily get entangled in the sea of language.

 

[pivoxa15]

Neither. The original car was made of all its original parts so neither of these two cars qualifies.
Ownership is a different (legal) matter.

In light of my previous post, 'neither' is the most appropriate answer.

 

[3mpathy]

so are humans like pi or like the ship? if there are peices that are constant, what are they?

 

[pivoxa15]

so are humans like pi or like the ship? if there are peices that are constant, what are they?

Humans are like ships because we are physical objects, not mental abstractions. I'd say that nothing physical (existing in space) can stay constant. Brownian motion suggets that things will move even if there is no cause.

 

[selfAdjoint]

Humans are like ships because we are physical objects, not mental abstractions. I'd say that nothing physical (existing in space) can stay constant. Brownian motion suggets that things will move even if there is no cause.

Like the ship, but dynamic. They used to think that nerve cells didn't regenerate, but that turned out to be wrong. So over a few years all your cells will die and be replaced by new ones. However YOU are not just a collection of cells but a process which is based on those cells and which has ongoing continuity independently of them.

 

[daveb]

Like the ship, but dynamic. They used to think that nerve cells didn't regenerate, but that turned out to be wrong. So over a few years all your cells will die and be replaced by new ones. However YOU are not just a collection of cells but a process which is based on those cells and which has ongoing continuity independently of them.

They now say nerve cells regenerate? Crap! I need to stop reading so much physics and start reading more biology. You have any info on where I can read about this?

 

[sameandnot]

the thinker is itself a thought.
thoughts, just like material are ever in flux. there may be more or less thoughts, in quantity, but the fleetingness of thoughts is paralleled only by the fleetingness of material.

what then is the self? the sense of continuity? is it merely a chain of thoughts?

if there is no thought, what is the self? when thought ceases, so too does the thinker.

what is it that provides the sensation of continuity, then?
like all sensations, it appears, continuity arises from the peculiar, ineffible quality of awareness. so it is with thoughts. there must be awareness to experience sensations, to think and the like. oddly, it seems, that thought has identified itself with this awareness, which it conceives is the thinker of thoughts.
but, i wonder if the infusion of awareness/consciousness with a sufficiently complex organism yields thinking, as a process of the material organism. this does not seem infeasible, and might be the common consensus, but, then, who am i? who is the self? is the self the consciousness, or is it the chain of thoughts that are triggered by the quality of consciousness/awareness in an organism?

in this way, is the self any different from the ship that is subject to constant change?

 

[Dawguard]

In a strictly matieriel sense it is not the same object. All the atoms are different, so it is a different object. However once the label has been aplied to it by humans, the thing that makes it Theseus' Ship is not inherent in matter. It is the idea of the ship that defines it, so in that regard it is the exact same ship. The difference is between the label and the object.

 

[Orefa]

It is the idea of the ship that defines it, so in that regard it is the exact same ship.

This interpretation can certainly be used. It is in fact used all the time in daily life for practical reasons that are fairly obvious: minute details are not normally relevant. But from a philosophical perspective we must recognize that it is a flawed interpretation that let's Theseus's ship be in two different museums at the same time, or my pair of socks be in two laundromats at the same time. Note that this does not negate the usefullness of an identity that persists over time. It merely points out that there is an important difference in concepts. We must be careful to use a labeling method that is suitable to the situation at hand. This choice can be important.

 

[pivoxa15]

the thinker is itself a thought.
thoughts, just like material are ever in flux. there may be more or less thoughts, in quantity, but the fleetingness of thoughts is paralleled only by the fleetingness of material.

what then is the self? the sense of continuity? is it merely a chain of thoughts?

if there is no thought, what is the self? when thought ceases, so too does the thinker.

what is it that provides the sensation of continuity, then?
like all sensations, it appears, continuity arises from the peculiar, ineffible quality of awareness. so it is with thoughts. there must be awareness to experience sensations, to think and the like. oddly, it seems, that thought has identified itself with this awareness, which it conceives is the thinker of thoughts.
but, i wonder if the infusion of awareness/consciousness with a sufficiently complex organism yields thinking, as a process of the material organism. this does not seem infeasible, and might be the common consensus, but, then, who am i? who is the self? is the self the consciousness, or is it the chain of thoughts that are triggered by the quality of consciousness/awareness in an organism?

in this way, is the self any different from the ship that is subject to constant change?

I would say that the idea of the self is very much like the ship that is subject to constant change. The thought of self is from the material in your brian. Just like I could alter the pieces of the ship, I could alter the pieces of your brian and your conception of self will alter. This is because there is no strict defintion of self, just like there is no strict definition of ship.

However mathematical entities like pie will not alter even if your brain cells are altered because with mathematical entities, most of the time, it is all or nothing. It is the number pie or it is not.

Wouldn't it be good if everything were like mathematical entities? That way problems like Thesus's ship would not arise. Plato was smart, he did not suggest Forms for nothing.

 

[jhe1984]

I think it was Aristotle who suggested, if not said exactly, this quote:

"God is a thought thinking itself."

Whatever else it may mean, it sounds nice. Thought it sounded relevant.

 

[NavyMan]

Well what happens if we get all our biological parts, minus the brain, replaced with synthetic or bionic replacements. Or even have some way of replacing our brain, thus eleminating all biological components?:yuck:

 

[pivoxa15]

Well what happens if we get all our biological parts, minus the brain, replaced with synthetic or bionic replacements. Or even have some way of replacing our brain, thus eleminating all biological components?:yuck:

The conclusion I have reached is that if you are going to apply the word entity (in the strictest sense) to something than that something must be a pure thing which never changes even a little bit. If it did change than it would be something else and have another name. So mathematical entities are good objects to label but a physical object is not. We may use the word loosly in everyday language but if the word is to be scrutinised than there is no hope if used on physical objects. Paradox will natually emerge.