Bruno Marchal wrote:
On 25 Mar 2015, at 12:25, Quentin Anciaux wrote:
Multiple realisation does not undermine physical supervenience... what
undermine it, is that you're forced to accept (with the movie graph
argument) that the consciousness is supervening on the movie + broken
gate... which is absurd, and the conclusion is either that physical
supervenience is false or computationalism is...
Good summary. If you accept physical supervenience, you need to accept
that non active part of the brain have active part in the brain, basically.
It makes clear that it is not the material brain or material computer
which does the thinking, but the abstract person run by any sufficiently
robust programs, with a robustness defined to its most plausible
computations above its substitution level above and below the
substitution below.
I think that all the MGA establishes is that if the film taken of the
physical states of the brain is a good copy, then consciousness can
supervene an that copy as well as the original.
Let me try to summarize the argument as I see it. We are conscious and
we have brains that seem to be connected with the conscious state, such
that a reasonable first model is that consciousness supervenes on the
physical brain -- we alter the brain, we affect the conscious state, and
the conscious state, being deterministic, reciprocally affects the
brain. (Changed thoughts are correlated with changed brain states.)
The observation is then made that we could, quite probably, simulate the
brain state to any desired level in a computer (universal Turing
machine). The question is: does consciousness supervene on the physical
state, or on the abstract calculational state represented by the computer?
Given that the computer simulation has the same conscious state as the
original brain, it follows that copies of the conscious state can be
made. In so far as these are accurate copies of the original physical
state, they are all the same conscious moments -- we only create
different consciousnesses when the inputs differ between copies -- and
then the states are no longer identical.
None of this argues against conscious supervening on the physical rather
than on an abstraction in Platonia. The MGA, as I understand it, was
designed to undermine this conclusion. The movie image projected on the
original neural plate recreates the original conscious state. But we can
degrade the neural plate. As long as we project the same movie copy, the
conscious state is unchanged. It is argued that this is absurd. As far
as I can tell, such an argument hinges on the notion of conterfactual
equivalence: the original movie and the degraded plate are not
counterfactually equivalent.
I simply say, so what! Counterfactual equivalence does not have any
independent justification, and it is highly unlike to be sensible, even
in the context of computationalism. Basically, because the simulation of
any given conscious state can be carried out an any computer -- whatever
the architecture, physical construction, or programming language. As
long as the original state is accurately simulated, the conscious state
will be the same. But these different instances of the calculation are
generally not counterfactually equivalent, nor need they be -- they only
have to simulate the original state to the required degree of accuracy
-- they may differ to any degree whatsoever for their calculated states
before and after the target conscious moment.
This comes back to my original question: since all possible programs are
run by the dovetailer, how do we ensure that conscious beings see an
ordered and predictable world. Only a set of measure zero among all
possible programs would give that result.
Bruce
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
