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Article 6117 of comp.ai.philosophy:
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>From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: Hypothesis: I am a Transducer (Formerly "Virtual Grounding")
Message-ID: <1992Jun5.205056.18070@bronze.ucs.indiana.edu>
Keywords: quantum mechanics,consciousness
Organization: Indiana University
References: <1992Jun5.130022.26367@cs.ucf.edu> <1992Jun5.140801.23688@cs.yale.edu> <1992Jun5.170559.305@cs.ucf.edu>
Date: Fri, 5 Jun 92 20:50:56 GMT

In article <1992Jun5.170559.305@cs.ucf.edu> clarke@acme.ucf.edu (Thomas Clarke) writes:
>In article <1992Jun5.140801.23688@cs.yale.edu> mcdermott-drew@CS.YALE.EDU (Drew McDermott) writes:

>>The many-worlds interpretation dispenses with conscious observers,
>>which is good, because if there is ever to be an explanation of
>>consciousness as a property of matter, our fundamental theory of matter
>>cannot presuppose consciousness.

>Many worlds does eliminate the requirement that a conscious
>observer determines the moment of observation.  It does so,
>however, by postulating that all possible outcomes of all
>possible experimental observations occur and continue to 
>evolve in parallel.  Conscious observers then must have
>the peculiar ability to sense only one possible observational
>track.  How this observational track is selected is not
>specified.  It always struck me that selecting a single 
>observational track for a conscious observer in Many Worlds 
>was exactly equivalent to the conscious observer "collapsing
>the wavefunction" in more conventional approaches.  No matter
>which way you slice it, consciousness seems to still have a 
>peculiar relation to the physical world in quantum mechanics.

There doesn't need to be any "selection" of a "single observational
track".  All of these "observational tracks" will have conscious
observers in them.  To be sure, to each of those observers, it will
seem as if a single track has been slected, but that's just an
illusion of perspective.  One has to get away from a simple
deterministic view of personal identity here: you might think
that there's a fact of the matter about which of several "tracks"
*I* will be in in the future -- as opposed to those other beings
that aren't "me".  But there need be no such facts.  All of those
future beings bear exactly the same relation to me now.

What does need to be explained in the Everett interpretation is why,
given that the world is a giant superposition, there are observers
that are conscious of seemingly non-superposed states.  But that's
not too much of a problem, with a decent theory of consciousness
in hand: such observers are only determined by a limited part of
the wavefunction, namely by information present in one of its
eigenstates; they simply don't have access to information elsewhere
in the wavefunction.

I don't agree with Drew McDermott that the Everett interpretation
"dispenses" with conscious observers; they're still around, and
understanding the role of observership helps us understand the
theory (in particular, it helps us understand why the world doesn't
*seem* superposed).  It's just that on this interpretation,
consciousness doesn't play any fundamental role in the physical
laws (which is probably what McDermott meant).  Which makes for
a much more satisfying physical theory, if you ask me.

-- 
Dave Chalmers                            (dave@cogsci.indiana.edu)      
Center for Research on Concepts and Cognition, Indiana University.
"It is not the least charm of a theory that it is refutable."


