On 05 Sep 2005, at 19:13, Hal Finney wrote:

Bruno writes:

I will think about it, but I do think that CT and AR are just making
the YD more precise. Also everybody in cognitive science agree
explicitly or implicitly with both CT and AR, so to take them away
from YD could be more confusing.


I think that is probably true about the Church Thesis, which I
would paraphrase as saying that there are no physical processes more
computationally powerful than a Turing machine, or in other words that
the universe could in principle be simulated on a TM.


Here I disagree completely. Church Thesis (CT) has nothing to do with physical processes. Note that this is a point where I think David Deutsch is confused with his new version he called Church Turing principle, and which I call "Deutsch's Thesis", and which is completely independent of Church Thesis. Church's thesis is just the thesis that all computable function are captured by LISP (or <add your favorite universal computer language>. It identifies an intuitive notion of computability with a formal one.

Now if comp is true, that is: if I am a turing-emulable (LISP- emulable, ALGOL-emulable, etc.) THEN the universe is not Turing emulable a priori. We can come back on this. Note that Nielsen's e^i*omega*t can be considered as a non turing emulable physical process which is physically possible.





I wouldn't be
surprised if most people who believe that minds can be simulated on
TMs also believe that everything can be simulated on a TM.

They are wrong. If minds are turing-emulable then indeed minds cannot perceive something as being provably non-turing-emulable, but minds can prove that 99,999...% of comp-Platonia is not turing-emulable. And the UDA shows that physics emerge from that comp-Platonia (arithmetical truth).




(I don't see the two philosophical questions as absolutely linked, though. I could imagine someone who accepts that minds can be simulated on TMs, but who believes that naked singularities or some other exotic physical
phenomenon might allow for super-Turing computation.)

Absolutely. And the UD generates complex things which from the first point of view of machine will be non-turing emulable.



But isn't AR the notion that abstract mathematical and computational
objects exist, to the extent that the mere potential existence of a
computation means that we have to consider the possibility that we are
presently experiencing and living within that computation?  I don't
think that is nearly as widely believed.


You are right. But this is exactly the point which follows from the Movie-Graph-Argument (or Maudlin's Olympia).
It is highly not obvious at all!!!
It is not AR. AR is so obvious that people (who are not professional logician) take time to understand it needs to be assumed. But AR is just the belief that the arithmetical truth is independent of us. Would an asteroid hit Earth and destroy all life on it, would not change the fact that 17 is a prime number, or that Goldbach conjecture is true or false.




That simple mathematical objects have a sort of existence is probably
unobjectionable,

That's AR.


but most people probably don't give it too much thought.
For most, it's a question analogous to whether a falling tree makes a
noise when there's no one there to hear it. Whether the number 3 existed
before people thought about it is an abstract philosophical question
without much importance or connection to reality, in most people's minds,
including computationalists and AI researchers.

Because most ignore the difference between first and third, singular and plural, point of views. Mathematically they confused p, Bp, Bp & p, Bp & Dp, etc. But Godel's B provide counterexamples.



To then elevate this question of arithmetical realism to the point
where it has actual implications for our own perceptions and our models
of reality would, I think, be a new idea for most computationalists.


Yes. But they ignore UDA. They ignore the first person indeterminacy. They are bounded by they Aristotelian idea that computationalism and mechanism are allied to materialism, naturalism, physicalism. My work shows comp is incompatible with materialism, naturalism, physicalism.



Right here on this list I believe we've had people who would accept
the basic doctrines of computationalism, who would believe that it is
possible for a human mind to be "uploaded" into a computer, but who
would insist that the computer must be physical!


I will come back on this when I will comment your post where you point us to Maudlin's paper. I could also ask you what you mean by "physical" and then what are you assuming precisely. I do not assume anything physical.



A mere potential or
abstractly existing computer would not be good enough.  I suspect that
such views would not be particularly rare among computationalists.


You are right, but they are wrong. I can have an intuition with UDA + AUDA + OCCAM. But the proof is given by UDA + Movie-graph. UDA does use a physicalist base (a concrete running of a concrete UD), and the Movie-Graph does eliminates that assumption. Somehow the movie-graph shows that not only a machine cannot distinguish a physical reality from a virtual reality, but a machine cannot distinguish a physical reality from an arithmetical reality.

Bruno

http://iridia.ulb.ac.be/~marchal/



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