Re: computationalism and supervenience

From: Bruno Marchal <>
Date: Sun, 3 Sep 2006 15:03:02 +0200

Le 03-sept.-06, à 05:07, Stathis Papaioannou a écrit :

> The dynamism part can be provided by a simple physical system such as
> the idle passage of time.
> If you allow for parallel processing you don't need much time either.
> This leads to a situation whereby
> every computation is implemented by universe with a single electron
> enduring for a nanosecond, for
> example. I can't quite see how to get rid of the electron, but
> Maudlin's and Bruno's conclusion from
> this seems to be that it is absurd and implies that the mental does
> not actually supervene on the physical.

I think you mix the Mallah Putnam implementation problem, related to
the idea that any piece of matter could compute, and Maudlin's thought
experiment showing the incompatibility of the physical supervenience
thesis (that consciousness should supervene on the physical activity of
a computer running the computation) and computationalism (that
consciousness is invariant for a digital functional substitution made
at some level).

Maudlin build first a digital machine, let us call it M, which do a
computation PI (Maudlin's name for it) which we suppose does correspond
to a genuine consciousness experience (for example some remembering of
the taste of cocoa).
Suppose that during the running of that particular computation PI, the
register r1, ...r67 are never used. Maudlin argue that if consciousness
is attached to the physical activity relevant for the computation, we
can retrieve those unused part of the computer, without changing the
consciousness experience.
He shows then that he can managed to build a version of M,
proto-olympia (say) which has almost no physical activity at all when
he follows the PI computation.
Proto-olympia is *physically* accidentally correct for PI, but no more
counterfactually correct.
Then Maudlin reintroduces the unused parts, the Klaras, which
reintroduces the counterfactual correctness, WITHOUT ADDING any comp
relevant physical activity (if not, it would mean the level is
incorrect(*)). So comp + physical supervenience (phys-sup) would force
us to associate any consciousness experience to any physical processes.
And that would kill comp! So sup-phys -> NOT comp, or equivalently comp
-> NOT sup-phys.
We still have notions of computational supervenience, where persons and
consciousness are associated to relative number theoretical relations.


(*) This explains also why, AT THIS STAGE, to move on a physical
multiverse would not help (Russell's Standish move), unless it makes US
non computable, but that would be equivalent to abandoning both comp
and the quantum (given that quantum mechanics is quantum turing

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Received on Sun Sep 03 2006 - 09:05:02 PDT

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