Stephen writes

>     I really do not want to be a stick-in-the-mud here, but what do we base 
> the idea that "copies" could exist upon?

It is a conjecture called "functionalism" (or one of its close variants).
I guess the "strong AI" view is that the mind can be emulated on a 
computer. And yes, just because many people believe this---not surprisingly
many computer scientists---does not make it true.

An aspect of this belief is that a robot could act indistinguishably
from humans. At first glance, this seems plausible enough; certainly
many early 20th century SF writers thought it reasonable. Even Searle
concedes that such a robot could at least appear intelligent and
thoughtful to Chinese speakers.

I suspect that Turing also believed it: after all, he proposed that
a program one day behave indistinguishably from humans. And why not,
exactly?  After all, the robot undertakes actions, performs calculations,
has internal states, and should be able to execute a repertoire as fine
as that of any human.  Unless there is some devastating reason to the

> What if "I", or any one else's 1st person aspect, can not be copied?
> If the operation of copying is impossible, what is the status of all
> of these thought experiments?

I notice that many people seek refuge in the "no-copying" theorem of
QM. Well, for them, I have that automobile travel also precludes
survival.  I can prove that to enter an automobile, drive it somewhere,
and then exit the automobile invariably changes the quantum state of
the person so reckless as to do it.

If someone can teleport me back and forth from work to home, I'll
be happy to go along even if 1 atom in every thousand cells of mine
doesn't get copied. Moreover---I am not really picky about the exact
bound state of each atom, just so long as it is able to perform the
role approximately expected of it. (That is, go ahead and remove any
carbon atom you like, and replace it by another carbon atom in a
different state.)

>     If, and this is a HUGE if, there is some thing irreducibly quantum 
> mechanical to this "1st person aspect" then it follows from QM that copying 
> is not allowed. Neither a quantum state nor a "qubit" can be copied without 
> destroying the "original".

This is being awfully picky about permissible transformations. I
have even survived mild blows to the head, which have enormously
changed my quantum state.

> falsified, by the same experiments that unassailably imply that Nature is, 
> at its core, Quantum Mechanical and not Classical and thus one wonders: "Why 
> do we persist in this state of denial?"

Probably for the same reason that some people continue to be Libertarians.
It's a belief thing---the way you see the world.


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