On 12 May 2015, at 22:27, meekerdb wrote:
On 5/12/2015 3:25 AM, Bruno Marchal wrote:
On 12 May 2015, at 02:33, Bruce Kellett wrote: The fact that
projecting the film isn't a general purpose computer seems to me
to be a red herring. It was never claimed that projecting the film
of the brain substrate instantiated general consciousness -- the
only claim ever made here is that this projection recreates the
conscious moment that was originally filmed. That is all that is
required. General purpose computing and counterfactual correctness
are all beside the point. If the original conscious moment is
recreated, then the film is a computation in any sense that is
necessary to produce a conscious moment. This is sufficient to
undermine the claim that consciousness does not supervene on the
physical body.
The matter of whether the physical is primitive or not is also a
red herring. No such assumption is required in order to show that
the MGA fails to prove its point.
It is a reductio ad absurdum. If consciousnesss requires the
physical activity and only the physical activity, then the
recording is conscious. But anyone knowing what is a computation
should understand that the recording does not compute more than a
trivial sequence of projection, which is not similar to the
computation of the boolean graph.
I think there are five concepts of computation in play here:
1. An abstract deterministic computer (TM) or program running with
some given external input. This program is assumed to have well
defined behavior over a whole class of inputs, not just the one
considered.
OK. That is the standard concept (although the computation does not
have to be deterministic, but that is a detail here).
2. A classical (deterministic) physical computer realizing (1)
supra. This is what the doctor proposes to replace part or all of
your brain.
Yes, and this involves physics. But this is no more a computation in
the sense of Church-Turing, which does not refer to physics at all.
3. A recording of (2) supra being played back.
Nobody would call that a computation, except to evade comp's
consequences.
4. An execution of (1) with a classical (deterministic) computer
that has all the branching points disabled so that it realizes (1)
but is not counterfactually equivalent to (1) or (2).
This computes one epsilon more than the movie. That is, not a lot.
5. A physical (quantum) computer realizing (1) supra, in it's
classical limit.
That is the solution we hope for (as it would make comp and QM ally
and very plausible).
Bruno takes (1) to define computation and takes the hypothesis that
consciousness is realized by a certain kind of computation, an
instance of (1). So he says that if you believe this you will say
yes to the doctor who proposes (2) as a prosthesis. This
substitution of a physical deterministic computer will preserve
your consciousness. Then he proceeds to argue via the MGA that this
implies your consciousness will not be affected by using (4) instead
of (2) and further that (4) is equivalent to (3) and (3) is absurd.
Having found a reductio, he wants to reject the assumption that your
consciousness is realized by the physics of a deterministic computer
as in (2).
Whether (3) preserving consciousness is absurd or not (and I agree
with Russell that's to much of a stretch of intuition to judge);
There is no stretch of intuition, the MGA shows that you need to put
magic in the primitive matter to make it playing a role in the
consciousness of physical events.
this is not the reversal of physics claimed. The Democritan
physicist (nothing but atoms and the void) will point out that (2)
is not what the doctor can implement.
?
What is possible is realizing a prosthetic computation by (5). And
(5) cannot be truncated like (4); quantum mechanical systems can
only be approximately classical and only when they are interacting
with an environment. The classical deterministic computer (TM) is a
platonic ideal which, as far as we know, cannot be realized.
But then comp is false, as comp is a bet of surviving some digital
truncation.
Now that doesn't invalidate Bruno just developing his theory of the
UD and showing that it realizes QM and the wholistic quasi-classical
physical behavior of macroscopic systems in some limit.
Right. In the original thesis, UDA and MGA is used only to explain the
mind-body problem: the AUDA theory is explained as the main thing
before them; and then used to solve the UD and MG Paradoxes.
But I do think that they are strong argument, and easier than AUDA,
that's why I like to argue on this.
But I don't think he can just help himself to the conclusion that
there MUST BE some measure or some way of looking at the UD in which
this is so because the MGA has refuted Democritus.
Only Democritus + (CT+YD).
Bruno
Brent
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