On 04 Mar 2012, at 19:29, meekerdb wrote:
On 3/4/2012 12:15 AM, Bruno Marchal wrote:
On 04 Mar 2012, at 01:14, meekerdb wrote:
On 3/3/2012 12:43 PM, Bruno Marchal wrote:
comp can never be proved
False. By UDA.
so there is no point in worrying about it. I just assume it's
true because I could not function otherwise
Which is a nonsense. Nobody use the hypothesis that the brain is
a machine in their everyday life.
If tomorrow comp is refuted, you will not feel a difference. Just
that both matter and mind will be more mysterious.
In fact most people are unreflective dualists. They assume they
have a magic soul so that if their brain were replaced by a
computer 'they' would become a philosophical zombie while their
'real self' would be teletransported to heaven (or Platonia if
they happen to be mathematicians :-) ).
Yes. I agree. Many people are instinctively skeptical for comp,
unless they are molecular biologists.
Note that this is already explained in the modal logic of self-
reference: machine cannot know that they are machine, and they
cannot believe it either. Comp is necessarily (provably) counter-
intuitive. There is a natural tension between the hypostases S4Grz1
and G1, G1*, Z1*, X1*. The self-referentially correct machine
cannot avoid a conflict between any third person account of itsel
(G1) f, and its 1p "intuition" (S4Grz1).
On 3/3/2012 12:43 PM, Bruno Marchal wrote:
I understand that seems possible. That is why I avoid in the
thought experience, both amnesia, death, or anything which would
prevent the persons, before he opens the reconstitution box, in
W and M, to feel any different from the person in Helsinki, apart
from finding themselves in a box, and not knowing where they are.
In such case, to believe that you don't survive would prevent you
to believe that you can survive teleportation, and comp would be
But that seems to be equivocation on 'you'. 'I' have a certain
continuity of thought and more distant memories. The hypothetical
teleportation would necessarily (nomologically) produce a
discontinuity in thought, so my identity would depend on my
The equivocation of "I" is well illustrated by the duplication,
made possible by comp. But the problem is avoided in the definition
of comp by the quasi-operational "yes" doctor. (It is not entirely
operational because logically a zombie can also say "yes" to the
doctor, but of course we assume *you* are not a zombie).
Small changes in memory would still allow 'me' to identify myself
with the Helsinki person, but large ones, e.g. I remember living
in Brussels not Helsinki, would make 'me' a different person.
Sure. But, by construction, there are no change at all in the
memories. The personal memories are annihilated and reconstituted
'I' am an inference, or a construct, from my memory (including
Not only that. "you" are also a universal number/machine. It is
more ""I"" which is an inference than "I". The real first person,
captured by Theatetus, is really where ""I"" and "I" intersect, so
So the question as to which probability I have finding myself in M
or W is ill posed;
Here I strongly disagree. Despite what you say above, the question
is well posed. The candidate in Helsinki has all the information
needed + his assumption that comp is correct, which is part of the
inference. He knows in advance that he
No 'he' won't. He knows or expects in advance that there will be
two people who share his memories and feel like him.
Keep in mind that he believes also that he survives that experience.
But it is just a confusion of our language that assumes the
continuity of a single thing that can be duplicated.
There is no continuity. Only a computation which bifurcates.
I don't see that it's any different than taking a 3p view and
asking which body is the Helsinki one, the one in Moscow or the one
in Washington. Most people would say "Neither" and that similarly
one can say 'he' doesn't feel to be in either place, it is some
duplicates that feel they are in W or M. They are only identified
with the guy in Helsinki because they share many attributes with him
- i.e. similar body and memories.
But that would be an argulent for saying "No" to the doctor. The new
guy with the artificial brain, would be someone else, with a similar
body and memories, but still someone else.
But if you accept the idea that you survive teleportation, then you
survive duplication. It is just that you can't predict with certainty
which future among W and M, you will live, before the experience.
You might read my more detailed comment to John K Clark, and perhaps
will be reconstituted in both W and M. He knows with certainty
(with respect to his comp assumption) that in both W and M he will
find himself to be in one place, and that he cannot know which one
in advance without adding a magic ability contradicting comp. The
question bears explicitly on its singular future personal
experience, and in this situation, the question is as mundane than
any question about a well defined random variable. The duplication
will be, from its first person perspective, equivalent with a
Bernouilli experience, despite the equivocation of the "I". That's
why we do such experience, to avoid any problem due to the "I"
equivocation. All we need is to define the 3-I by the body
described at the right level, and the 1-I, which in UDA is nothing
more than the personal memory, which is supposed by construction to
be not altered in the annihilation/reconstitution move.
it assumes that there is one 'I' and we can ask where this 'I'
finds himself. But there is no 'I' in this sense.
Of course there is such an "I". Once your body has been
reconstituted in both place, they both knows very well where that
"I" feels to be, and this is known in advanced (believed and true,
given that we assume the candidate believe in comp and that comp is
Such an "I" is well defined. It is the owner of the memory together
with the fact that those memory are known true, by us.
But that "I" is not well defined because it can be duplicated and
hence the "owner of the memory" is indefinite.
Of course, that "I", the 1-I, is not well defined. In AUDA it is even
proved that it is not definable (accepting the classical theory of
But from his 1-I point of view, his *experience* is always well
defined, comp just makes it not predictable, like if he look at the
comp-multiplication movie (in my comment to JK Clark).
The "owner of the diary/memory" *is* the definition (not a complete
one!) of the "1-I", in the UDA. That's work well enough to get the
first person indeterminacy, and the reversal.
In the iterated WM duplication, most resulting persons, which by comp
are still conscious rational people, will see that their memory
contains incompressible random strings. So most will have a first
person experience of indeterminacy, and in the iterated duplication,
the compressible experience plays the role of the white rabbits. They
are excessively rare. That will be part of the mind-body problem in
comp. The UD plays a non trivial role, there, akin to the Everett
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