On 3/31/2015 6:58 PM, Bruce Kellett wrote:
Bruno Marchal wrote:
On 31 Mar 2015, at 07:17, Bruce Kellett wrote:
So I would reject the computationalist program right at the start -- I would not say
"Yes, doctor" to that sort of AI program.
Nor do I.
That is why I say that my definition of computationalism is weaker than most in the
literature.
Computationalism, as I defined it, assumes only the existence of a level of
substitution such that you survive with a digital (Turing emulable) functional
substitution made at that level.
In which case you have physical supervenience, and nothing else. The digital simulation
of brain functions is achieved on a physical computer after all, which is a physical
object itself -- simulating (primitive) physical processes.
In the six first step of the UD argument, I suppose the level high (but still
describing the biology of neurons and glials cells), to make the reasoning more easy.
But the conclusion hold up even for someone who say that to get its relevant actual
state, we need to simulate the while universe, from the big bangs, at the level of
superstring theory, with (10^(10^100)) hexadecimals exact.
Don't count on superstring theory!
This is because that dumb little Robinson Arithmetic emulates that "artificial brains",
infinitely often, and with sometimes *much* bigger number of decimals.
I find it hard to understand what you mean here. RA 'emulates' artificial brains? The
picture that comes to my mind is: if you write out the numerical sequence of digits,
123456789101112......, that sequence contains all possible subsequences. I cannot
remember whether this sequence is actually a normal number or not, but that seems likely.
Within this sequence is the Goedel number for my brain (or for the whole universe). And
it does not matter which encoding I use for Goedel numbers -- the normal number contains
them all. A very simple Turing machine (any modern computer) can churn out this sequence
of digits any time it likes (though it might take a long time to get to me or anyone
else!).
Is this anything like what you have in mind?
If it is, the mere existence of a static sequence does not comprise the dynamical object.
The passage of time is not the sequence of computational steps. I think the idea is that
conscious states can be computed in any order and their time relation is inherent (like
Barbour's time capsules). I see some problems with idea, but not the one you raise.
It is a description, not the reality, and it confuses the map with the territory. If the
description of a brain can be conscious, then the MGA fails.
My other main objection would be the white rabbit issue -- all magical states that are
nearly the same as me are also in the sequence.
Of course, I assume the Church-Turing thesis. This assumes some realism on the possible
digital machines and machineries, equivalent with realism on a tiny fragment on which
intuitionists and classical mathematicians agree. Most physicists used stronger
mathematical theories. And Brent made me realize that RA is even a strct finitisme in
Van Bendeghem sense. RA is consistent with there is a biggest number.QM.
Does this not constitute an (insuperable) problem for the simplest case? If RA is
consistent with a biggest number, then the sequence is not normal, and nothing useful
need be included.
May be comp is false, but that is why I make it precise and look for the consequence.
Without Everett QM I would still be sure it can't be true, but perhaps still study it,
for the beauty of mathematics.
You rely too much on Everettian QM -- which you can't even begin to derive in your
theory. The Everett relative state interpretation is only that, an interpretation of QM.
It is not an established theory, and any other interpretation of QM that gives the same
observational results would do as well. The MWI program based on Everett has many
problems of its own. It is very likely that in the final analysis, the Schroedinger
equation will be seen to be nothing more that a device for calculating probabilities --
it is merely epistemological, not ontological. FPI is then an illusion, and you cannot
use physics to support your theory -- particularly when there is no evidence that your
theory is even consistent with QM, much less physics.
Bruno's theory may fair better with a Quantum Bayesian interpretation than with MWI, since
he hopes to take conscious states as more fundamental and derive the physics. It would
lead to idealism instead of Platonism.
Brent
The irony, of course, is that proponents of the MWI rely on physical realism to justify
their position. Given comp, MWI collapses (pun intended :-) ).
Bruce
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