>Chris wrote:
>
>>[...] Computation
>>supervenes on physical structures, but you must take the entire
>>physical structure into account, including parts that happen to
>>be inactive during a particular run. Those parts change the
>>counterfactuals, and thus change the program.
>
>
Philosophers of mind are remarkably ingenious to find contrived systems
which reveal flaws in usual notions. I think that physicists would have a
very
hard time if the same deal of work would have been made to dispute their
definitions. I let you think of the following thought experiment :
How to know if there is an electric field somewhere in space ? usually
physicists answer that there is an electric field if a test charged
particle placed at this point would feel a force on it.
Now I propose you a system made of condensator that is initially neutral,
but coupled with a device that will detect the presence of any test charge
(for example another charge in unstable equilibrium at at local saddle
point of electric potential that would automatically be ejected by the
presence of this test charge and captured by a detector). As soon as a test
charge enter the condensator, the charge detector triggers a generator that
charges the condensator. The electric field does exist of course after the
test charged is introduced, but would you say that it exists BEFORE ?
I find that the problem of counterfactuals is quite similar.
Counterfactuals are a necessary condition for consciousness to exist, but
not a totally sufficient one- especially if you start to think of very
complicated devices like Mauldlin one's. It's obvious for me that our
consciousness requires an ACTUAL activity of the brain which makes it able
to handle counterfactuals, but it can not be used as a complete
characterization of conscious systems. I cannot imagine being conscious
with a flat EEG...
Gilles
Received on Fri Jul 30 1999 - 13:13:35 PDT
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