Since the worlds are both altogether different and materially identical, they can only differ in something immaterial. That would then be "being". — SolarWind

What about the space each world occupies? is it also identical for both worlds?

where one is person A in world WA and person Z in world WZ. — SolarWind

Already assumes your conclusion. You assume a "one" that can either reside in A or Z. Then you say that "one" is soul. You haven't proven anything, you begged the question.

Both worlds are materially identical by definition. However, they differ in who one *is* in this world. If I am person A or Z, I have the body and the memories of person A or Z, respectively. — SolarWind

If they are materially identical, then the being would be materially identical as well. The only difference is location.

Look at it this way. I have two salt shakers that are materially identical in different worlds. Does that mean the salt shaker has a soul? No, it just means there is a clone in a different space.

"that a "pointer" indicates who I am in the respective world. This pointer could be called "soul", even if it only bears a distant resemblance to the religious soul."

Really? Well wouldn't you need to first define what this religious soul was? What properties it has that are unique to it being a soul as opposed to anything else?

Well... lets give it the benefit of the doubt and allow you to define what this 'soul' is and what unique properties its has as opposed to say phenomenological awareness, or maybe thinking ability ... which can't obviously be unique to a sou7ld since they are the properties of just 'brain'. Its real easy for one thing to be LIKE another thing if you don't define either.

What about the space each world occupies? is it also identical for both worlds?

You compare two visions. They are not beside each other. They are alternatives. And they are not equal. It plays a role being one person or another. Don't you think so?

Since the worlds are both altogether different and materially identical — SolarWind

If these are parallel worlds that are identical, then they have the same "histories", and person A in one world would have the same memories and history as person A in the other world. Your statement above doesn't make sense.

If these are parallel worlds that are identical, then they have the same "histories", and person A in one world would have the same memories and history as person A in the other world.

Of course they are identical. This is the core of the proof, it is not a bug, it is a feature.

More formal speaking you compare world A = ({A,B,C, ... ,X,Y,Z} living as A) with world Z = ({A,B,C, ... ,X,Y,Z} living as Z).

Of course they are identical — SolarWind

Your original premise seems to resemble the ongoing arguments on this forum about identity and equality. Does A=B mean that A and B are the same? Is 2+2 the same as 4? That's as far as I can get in your proof. But it's original thinking.

It is incredible how such a simple proof can be so misleading. Two ideas are compared. Can two ideas be identical or only the same? It does not matter.

The central assertion of my proof is: WA = WZ (physical), but WA <> WZ (total), therefore something unphysical must exist.

As has already been pointed out in the very first response, an assertion is all you have going. You postulate a dualistic premise, then illustrate it with your two alternative worlds example. There is no proof here.

This proof supports dualism and refutes monism, since in monism world A and world Z would have to be identical, since they are materially identical. — SolarWind

As others have pointed out, you postulate a difference between materially identical worlds, then conclude that these materially identical worlds are different thus dualism. Your conclusion is in your premises: a circular argument.

There are already materially identical things in this material universe. Particles of the same kind are indistinguishable (this is empirically verified), to the extent that some people believe that every electron in the universe is the same electron bouncing forward (electron) and backward (positron) in time, the idea that spawned Richard Feynman's quantum electrodynamics: the most thoroughly tested physical theory of all time.

Materially indistinguishability is not sufficient to show dualism. All the electrons in the universe are identical, but can still be different in physical ways (state). They can also have identical state: a ground state hydrogen atom over there can have the same state as and is materially indistinguishable from a ground state hydrogen atom here.

You don't define what you mean by world, but I assume you mean "everything", i.e. a universe or reality, rather than a planet or phenomenological purview. If that is the case, it is difficult to insist on two identical but separate worlds. You would need some justification for saying WA is indeed different from WZ, which is again assuming your own conclusion.

As already mentioned, the worlds should not exist simultaneously, but alternatively. Thus the question does not arise "where" these worlds are.

A simple question: Would it make no difference to you whether you lead your current life or the life of another person, for example George Clooney, of course including his body and memories?

What you are looking for, Solarwind, is something that is not merely posited to make the ontological difference. You cannot insist that "who one is" constitutes a real basis for the distinction of being a singular "who"? Or, the singularity of "whoness" does not constitute the need for an ontological distinction.
OR DOES IT? They way to go is to examine this "I", the who in question. The matter turns to the self (and certainly not to physics). One has to make an examination of the self, and this is done via phenomenology: One begins the inquiry with the world itself, which constituted by the self, and therefore free of the nuisance of dualism (an absurd idea supposing that existence as presence is divisible), and one then faces the most authentic terms of analysis. The self becomes an altogether different concept, for it is not viewed through the lens empirical science but as it is presented in its most immediate describable features, and here, it is not ontology that rules, but meaning and ethics, and the self is first and foremost an agency of meaning. It is though this premise, the singularity, if you will, of meaning/value.

If you want to affirm the self, you cannot do this via trying to conceive of a different form of something that has absolutely no meaning to begin with, physical existence. A nonsense concept.

As already mentioned, the worlds should not exist simultaneously, but alternatively. Thus the question does not arise "where" these worlds are. — SolarWind

Therefore there is no basis upon which to insist they are different.

A simple question: Would it make no difference to you whether you lead your current life or the life of another person, for example George Clooney, of course including his body and memories? — SolarWind

The question is meaningless. "I" am Kenosha Kid. If you were speaking to George Clooney, "I" would be George Clooney.

As others have pointed out, you postulate a difference between materially identical worlds, then conclude that these materially identical worlds are different thus dualism. Your conclusion is in your premises: a circular argument. — Kenosha Kid

No, it isn't. It is simple set theory.

You simply compare the set {A*,B,C,...,X,Y,Z} with the set {A,B,C,...,X,Y,Z*}, where the star indicates which life you would live in the corresponding world.
It is possible that the persons are materially identical in pairs, i.e. A* =(material) A, B =(material) B, ... , Y =(material) Y, Z =(material) Z*. So {A*,B,C,...,X,Y,Z} =(material) {A,B,C,...,X,Y,Z*}, but of course also {A*,B,C,...,X,Y,Z} <>(total) {A,B,C,...,X,Y,Z*}.

See it as a proof of contradiction.

You simply compare the set {A*,B,C,...,X,Y,Z} with the set {A,B,C,...,X,Y,Z*}, where the star indicates which life you would live in the corresponding world. — SolarWind

That's your dualistic premise-conclusion right there. For someone who doesn't already accept dualism there is no you that is independently assignable and separable from the body that it "inhabits."

When you go to the toilet, how can you say you are the same person afterwards as before?

Afterwards you are lighter than before, so you cannot be identical with a body.

How about the brain? The parts in there do not change every 7 years like the body.

The brain changes every moment you learn or forget something => you are another person every minute.

Please explain how you can be identical with a dynamic object.

You simply compare the set {A*,B,C,...,X,Y,Z} with the set {A,B,C,...,X,Y,Z*}, where the star indicates which life you would live in the corresponding world.
It is possible that the persons are materially identical in pairs, i.e. A* =(material) A, B =(material) B, ... , Y =(material) Y, Z =(material) Z*. — SolarWind

In set theory, these would be the same set. Your insistence on a difference nonetheless is precisely the circularity in your argument. This is not a subtle point.

I suppose one could say that every brainstate is me? So as you say, as I forget my name, there will be a brain state that correlates with it.

I am not opposed to dualism though, just trying to poke and understand.

In set theory, these would be the same set. Your insistence on a difference nonetheless is precisely the circularity in your argument. This is not a subtle point. — Kenosha Kid

Let's assume that reincarnation is true.
Would it make a difference to you which creature you were reborn as?

I suppose one could say that every brainstate is me? So as you say, as I forget my name, there will be a brain state that correlates with it. — DoppyTheElv

How is the brain state defined? Let's assume that a super technology makes it possible to replace every neuron with a functionally identical chip and turn your brain into a computer.

Would you then be that computer or would you be dead and the computer would just claim to be you?

If I were the exact meat of my brain I'd be dead.
If I'd be the function that the brain does, which if the computer takes my brain over but still performs the same functions then I'd be okay.

Usually survival here is dependent on continuity and since it's changed gradually I should be fine.

In set theory, these would be the same set. Your insistence on a difference nonetheless is precisely the circularity in your argument. This is not a subtle point.
— Kenosha Kid

Let's assume that reincarnation is true.
Would it make a difference to you which creature you were reborn as? — SolarWind

The question is not pertinent to the quote, or to me, frankly, as I don't concern myself with magic. Reincarnation is not similar to two things being identical.

Sure, reincarnation could be a nice tool to convey a point which Solar might want to make. Specifically a point about personal identity. So you're kind of just red herring it.

When you go to the toilet, how can you say you are the same person afterwards as before? — SolarWind

Wow. That took an unexpected turn.

OK, I think we are done here.

Sure, reincarnation could be a nice tool to convey a point which Solar might want to make. Specifically a point about personal identity. So you're kind of just red herring it. — DoppyTheElv

I'm not denying its relevance to a separate point. I'm saying it's irrelevant to the post he quoted. As I say, fantasy is not my bag.

@Kenosha Kid and @SophistiCat
I think the original argument can be put easier with clones.
The good old teletransporter problem would have sufficed to make the point that Solar is trying to make.

If you step into a teletransporter which scans your entire being down to the lowest level possible and recreates it at a distant place. Would that being recreated there be you? Would it seem as if you step in and step out on the moon?

Now imagine that it breaks and that you are not broken down in the beginning but still creates you on the moon. Now there is 2 of you. Which one of you 2 is the original you and why? Surely if this is possible then a person cannot merely be its biology. Because then you and you 2 on the moon would share a mind but different bodies. There has to be a pointer, as Solar calls it. That indicates which one of them is you. He calls this the soul.

Thats veeery roughly how the problem goes. Sorry if it's written quite haphazardly (it is) I'm allowing my hobby to interfere with my online lessons ;p

I think the original argument can be put easier with clones.
The good old teletransporter problem would have sufficed to make the point that Solar is trying to make.
... — DoppyTheElv

That makes more sense, but as I said earlier:

Materially indistinguishability is not sufficient to show dualism. All the electrons in the universe are identical, but can still be different in physical ways (state). They can also have identical state: a ground state hydrogen atom over there can have the same state as and is materially indistinguishable from a ground state hydrogen atom here. — Kenosha Kid

The broken teleporter is a nice redux of the ship Theseus paradox which concerns continuity of identity. It is essentially a language problem as far as I can see. In everyday scenarios, we don't need to worry about discontinuities of form alongside continuities of physical constitution or vice versa: my physical constitution gradually changes but I remain me albeit with a time-dependent physical constitution.

The ship Theseus challenges the importance of continuity: if a ship identical to Theseus is built out of all the original parts of Theseus, is it the Theseus? Have we not rebuilt the original Theseus? Here we're talking about instantaneous form and constitution. But if the original Theseus has had all of its parts gradually replaced and us still out there, isn't that still the Theseus? Here we're talking about continuity.

The linguistic issue is that, based on our experience with language, we have one word to describe two things that we can easily differentiate. One simply has to choose more careful language if this becomes a real problem. For what it's worth, the "identical parts" idea of identity seems like a non-starter, since when I say "I", I am referring to a continuous thing that does not have static components. The "original you" or the "original Theseus" does not have any relevance in that case.