2010/1/3 Nick Prince <m...@dtech.fsnet.co.uk>:
> HI Bruno
> Thank you so much for your answers to my queries so far.  I really
> need to do some more thinking about all that you have said so far and
> to understand why I am having difficulty replacing a real physical
> universal machine existing in the future (like Tipler suggests) or a
> great programmer existing now (like schmidhuber suggests) with your
> arithmetical realism.  I also need to search some previous posts to
> make use of past discussion topics that are relevant. Perhaps my
> background makes me a physicalist who can currently accept a milder
> form of comp.  However, I want to explore your position because I
> think it makes sense in so far as I think it is less vulnerable to the
> threat of infinite regressions like in  Schmidhuber’s great programmer
> (or even the greater programmer that programmed him).  Your version of
> computationalism would still be valid if either or both of the two
> options above were true. Herein lies its appeal to me (both
> fundamental and universal).
> I would like to read up on logic and computation as you suggest. I
> have read about all the books you recommend . However, can you suggest
> topic areas within these texts which I can  focus on to help me get up
> to speed with the problems I have regarding arithmetical realism with
> the UDA?  There is much that could perhaps be left out on a first
> reading and to my untrained eyes, it’s difficult to know what to omit
> (for example what would godels arithmetisation technique come under?
> (Googling it brings not much up).  Sorry but I haven’t ordered any
> books yet so I can’t look into them.
> Is there an English translation of your Ph.D. thesis yet?  Sorry but I
> can’t do French. My thanks and best wishes.

My justification for the hardwareless computer is the fact that any
computation can be mapped onto any physical process, in the same way
that any English sentence can be mapped onto any string of symbols.
Such a post hoc mapping would be useless to an observer trying to
extract meaning from the symbols or the result of a calculation from
the computer, since he would have to figure out the mapping himself
and he would have to know the answer he wants before doing this. With
the right key Bruno's PhD thesis contains an account of next week's
news, but so what? If you look at it the right way the dust swept up
by a storm is implementing a Turing machine calculating the digits of
pi, but what good does that do anyone? The claim that codes and
computations lurk hidden all around us could be taken as true but
trivial, or perhaps defined away as untrue on account of its
triviality. However, there is a special class of computations to
consider: computations that give rise to conscious observers in
virtual universes that do not interact with the environment at the
level of the substrate of implementation. If such computations are
possible (i.e. if comp is true) then it doesn't matter that no
external observers have access to the mapping that would allow them to
recognise them, for these computations create their own observers,
bootstrapping themselves into non-triviality. The physical process
"sustaining" the computation need not even be as complex in structure
as the computation: the computation could be mapped for example onto a
repetitive process, the idle passage of time, even a single instant of
time implementing the parts of the computation in parallel. And if we
get that far, it's obvious that the physical process does nothing, and
we may as well map the computation onto the null set. It is obvious
that the entire structure of the computation is contained in the
mapping, and the mapping is a platonic object, not dependent on being
written down or even understood in the mind of an external observer.

Stathis Papaioannou


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