On 13 Feb 2010, at 19:48, Jack Mallah wrote:
--- On Fri, 2/12/10, Bruno Marchal <[email protected]> wrote:
Jack Mallah wrote:
--- On Thu, 2/11/10, Bruno Marchal <[email protected]>
MGA is more general (and older).
The only way to escape the conclusion would be to attribute
consciousness to a movie of a computation
That's not true. For partial replacement scenarios, where part of
a brain has counterfactuals and the rest doesn't, see my partial
brain paper: http://cogprints.org/6321/
It is not a question of true or false, but of presenting a valid or
non valid deduction.
What is false is your statement that "The only way to escape the
conclusion would be to attribute consciousness to a movie of a
computation". So your argument is not valid.
OK. I was talking in a context which is missing. You can also conclude
in the prescience of the neurons for example. The point is that if you
assume the physical supervenience thesis, you have to abandon comp and/
or to introduce magical (non Turing emulable) property in matter.
I don't see anything in your comment or links which prevents the
conclusions of being reached from the assumptions. If you think so,
tell me at which step, and provide a justification.
Bruno, I don't intend to be drawn into a detailed discussion of your
arguments at this time. The key idea though is that a movie could
replace a computer brain.
What do you mean? I guess you mean: COMP + phys. supervenience entails
that a movie can replace a computer brain.
The strongest argument for that is that you could gradually replace
the components of the computer (which have the standard
counterfactual (if-then) functioning) with components that only play
out a pre-recorded script or which behave correctly by luck.
OK.
You could then invoke the 'fading qualia' argument (qualia could
plausibly not vanish either suddenly or by gradually fading as the
replacement proceeds) to argue that this makes no difference to the
consciousness. My partial brain paper shows that the 'fading
qualia' argument is invalid.
I may be OK with your point, but I am not using the 'fading qualia'
argument. Just the physical supervenience (to show it absurd by
'reductio').
I think there was also a claim that counterfactual sensitivity
amounts to 'prescience' but that makes no sense and I'm pretty sure
that no one (even those who accept the rest of your arguments)
agrees with you on that.
It is a reasoning by a an absurdum reduction. If you agree (with any
computationalist) that we cannot attribute prescience to the neurons,
then the physical activity of the movie is the same as the physical
activity of the movie, so that physical supervenience + comp entails
that the consciousness supervenes on the movie (and this is absurd,
mainly because the movie does not compute anything).
Counterfactual behaviors are properties of the overall system and
are mathematically defined.
But that is the point: the counterfactuals are in the math. Not in the
physical activity. That is why comp forces the computational
supervenience. But then the appearance of the physical world(s) will
eventually be in need to be recover from the mathematical computation.
Jack Mallah wrote:
It could be physicalist or platonist - mathematical systems can
implement computations if the exist in a strong enough (Platonic)
sense. I am agnostic on Platonism.
This contradicts your definition of computationalism given in your
papers.
I quote your glossary: <<Computationalism: The philosophical
belief that consciousness arises as a result of implementation of
computations by physical systems. >>
It's true that I didn't mention Platonism in that glossary entry (in
the MCI paper), which was an oversight, but not a big deal given
that the paper was aimed at physicists. The paper has plenty of
jobs to do already, and championing the possibility of the
Everything Hypothesis was not the focus.
I don't follow you. The point is not the everything hypothesis, just
that the movie graph makes consciousness supervene on the computations
(in their usual mathematical meaning) and not on the physical
activity, which has to be redefine from the structures of the "many
computations".
On p. 14 of the the MCI paper I wrote "A computation can be
implemented by a physical system which shares appropriate features
with it, or (in an analogous way) by another computation." If a
computation exists in a Platonic sense, then it could implement
other computations.
But here you don't distinguish the first and third person points of
view. No universal (mathematical) machine can know which computations
bear it, and its next personal state has to be recovered from the
statistics on the possible relative continuations.
Bruno Marchal
http://iridia.ulb.ac.be/~marchal/
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