Re: The copy paradox

Hal Finney (
Tue, 4 Nov 1997 12:33:11 -0800

Brent Allsop, <>, writes:
> For discussion purposes, I'll use the names Dup and Trans.
> Dup1 walked into a non destructive transporter and walked out of this
> same machine unchanged, yet scanned. Then an identical Dup2 walked
> out of the reproducer part some distance away from this scanning
> machine. Trans1 walked into a similar scanning machine but was
> completely taken apart atom by atom before an identical Trans2 was
> constructed out of different yet identical stuff some distance away.

I don't fully agree with your discussion, although I believe that it
is intended to be a somewhat simplified discussion of the issues.

> The problem of what it would be like is similar to the problem
> of other minds.

I'm not sure what you mean by "what it would be like". It seems quite
easy to me to imagine what it would be like to be any of the people
(who are alive) in this experiment (assuming I were the person who was
involved at the beginning). It is hardly more difficult than it is for
me to imagine what it will be like for me to go to the gym this afternoon,
or undertake any new experience.

This does not seem similar to the problem of what it would be like to be
another mind.

> Of course if you are Dup1 you will be extremely
> annoyed at the way Dup2 continually says he is the real Dup.

No, I wouldn't, for two reasons. First, Dup2 would not say such a thing
in those words. He would recognize that the whole issue of "the real
Dup" is poorly defined in this situation. He would argue that he had
as much claim to being a continuation of the original as Dup1 does, and
Dup1 would fully agree with him. Each would recognize the symmetry of
the situation and each would fully agree about the facts. There would
be no annoyance at the other.

> And of
> course you wouldn't want to be Trans1 because he was destroyed even
> though Trans2 claims he is the same.

I had the impression that "Trans1 walked into a similar scanning machine".
I would have no objection to being the person who walked into that
scanning machine, so long as the disassembly was quick and painless.
(I'm unclear on the difference between Trans and Trans1.)

Trans2 would not claim he was the same, because he would know that such
simple-seeming claims rely on our intuition from a world where copying is
not possible, and are inappropriate in this situation. He would, rather,
claim to have as justifiable a claim to being a continuation of Trans1
as a person who wakes up in the morning does to being a continuation of
the person who fell asleep the night before.

> If you were Trans2 you would
> have no way of directly consciously knowing or remembering that Trans1
> was destroyed and believe that you were the original transported
> Trans.

Assuming you are aware of the workings of the machine, you would know
these things even without having directly consciously experienced
the disassembly of Trans1 (or your own assembly, for that matter).
You would not believe that simple questions about whether you are the
same as someone else have simple answers until you have defined your
terms more precisely.

> Also If you were Dup2 you would believe that you were the
> original Dup and Dup1 would equally annoy you by claiming he was the
> real Dup.

There would be no annoyance, as I described earlier. Both parties are
fully informed and agree about the situation.

> The primary answer is, if you are the same, you will not be
> able to tell the difference between the two, including the particular
> feelings and memories being felt by the two now separate copies. If
> you were dup1, you would feel exactly the same as dup2.

I'm not sure that the concept of trying to tell the difference between
the two (from the inside!) is meaningful. It calls to mind an image
in which our consciousness first exists inside dup1, then flies over
to the inside of dup2 where we poke around and see whether things seem
about the same or not.

Actually each of dup1 and dup2 has their own fully integrated
consciousness. They start off in the same state and immediately begin
to diverge. I am sure we all agree about this.

> "Then what is it that is you?" one may ask. I believe, it is
> your state or shape.

This definition has a couple of problems. It is a bit misleading to use
the term "shape" because that often refers to the external boundaries of
your physical being, in other words, the shape of your body. Your term
"state" is more reasonable, but the problem is that the state is constantly
changing. "You" can't be defined as any one state, or else you would
only be you for one tiny instant. You need to describe what kinds of
variation of the state are permissible in order to still have it be "you".

> Dup1 and Dup2, after living a day, their state would start to
> diverge.

Their state would start to diverge instantly.

> Hence, they would become different people. This would be
> similar to the way you are different than the you that existed
> yesterday because of your new memories and other changes. To the
> degree that we are the same as our parents, we are the same person.
> To the degree that we are in a different state, we are different
> people.

I was following this OK until you mentioned our parents. We are not the
same people as our parents. This is not at all analogous to the way that
we are the same people as we were yesterday. There is no continuity of
brain state from parent to child, among humans. Maybe this analogy could
work with a race which reproduced by fission, like amoebas, or like we
will become once uploading or duplication is possible.

> One of the primary reasons we are unsatisfied with such an
> answer has a lot to do with the philosophical "problem of other
> minds".

For myself, the answers I find are completely satisfying, and I don't
see that it has much to do with the problem of other minds. Since we
are dealing with duplicates, the minds at the moment of duplication or
identical and there is no otherness.

> We simply can't "eff" what it is like to be us, and we
> thereby can't know if our copy is really indistinguishable from
> ourselves.

Not sure what "eff" means here, but if it refers to some form of
perception, it is odd that you would claim that we can't tell what it is
like to be us. Most people would say the opposite, that we can *only*
tell what it is like to be ourselves, but that we can't tell what it is
like to be someone else.

> Maybe the copy is some unfeeling (or "absent qualia")
> zombie simply acting the same?

No more reason to suppose that than to suppose that I am a zombie. The
duplicate is structurally identical to me.

Besides, nobody takes seriously the prospect that other people are
zombies. This is not what I think of as the problem of other minds.
Rather, that is the problem of what it is qualitatively like to be someone
else, how their sense of self differs from our own. Again, in the case
of a duplicate we have every reason to believe that at the moment of
duplication the qualia are in fact identical for the two duplicates.

> If we can solve the problem of other
> minds by discovering what qualia and consciousness really are
> objectively we can eliminate such dilemmas or "conundrums", or
> "paradoxes". We simply must be able to "eff" the ineffable. Such
> (mind melding?) will solve all these problems.

It's not clear to me how mind reading or mind melding would really solve
anything related to duplications. I suppose it would put to rest the
fears that other people may be zombies, but that is not something I take
seriously. It would presumably also confirm that the mental states at
the moment of duplication are matches, which would certainly be expected
given that the brain states are the same. It would therefore rule out some
bizarre nonphysical theories of brain behavior (like God breathing our
thoughts or something), but these are unlikely to be taken seriously
even without mind reading.