From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rpi!think.com!ames!ncar!noao!arizona!arizona.edu!NSMA.AriZonA.EdU!bill Thu Dec 26 23:57:25 EST 1991
Article 2300 of comp.ai.philosophy:
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>From: bill@NSMA.AriZonA.EdU (Bill Skaggs)
Newsgroups: comp.ai.philosophy,sci.philosophy.tech
Subject: Re: red light / blue light scenario
Message-ID: <1991Dec19.222126.2296@arizona.edu>
Date: 20 Dec 91 05:21:25 GMT
References: <1991Dec20.004238.11206@smsc.sony.com>
Reply-To: bill@NSMA.AriZonA.EdU (Bill Skaggs)
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Mark Corscadden:
>I'm posting this scenario in the hope that some folks will find it
>interesting enough to explain what they think would happen and why.
>In addition to sci.philosophy.tech, I've cross-posted to
>comp.ai.philosophy because of the significant level of interest there
>in the physical basis of subjective experience.
>
>  Red Light / Blue Light Scenario
>
>  You lie down on a bed which has a blue light on the ceiling directly
>  above you.  Take a good look at the blue light above, and then close
>  your eyes and relax.  Next to you is an identical bed, but this one
>  has a red light on the ceiling above it.  At this instant a perfect
>  physical duplicate of you is created instantaneously and placed on the
>  bed next to you.  You are not physically effected in any way whatsoever.
>
>  The light above you was blue when you closed your eyes.  Do you think
>  it's possible that you will see a red light when you open your eyes
>  again?  This is speaking from a purely subjective point of view; what
>  would it be like to *experience* this scenario?

First a reference:  the essay "Where was I?" by Dennett in "The
Mind's I" (edited by Dennett & Hofstadter) does a great job of
clarifying the issues raised here.

Now a response:  

There is no good answer to the question, because in the situation
described, the word "you" does not have a consistent meaning.

The notion of *identity* is useful in our world, but only because
our world has certain properties, of which object permanence and
object continuity are the most important.  Our usage of the
concept of identity implicitly assumes these properties hold; --
if they do not, our usage falls apart.

We don't need notions as complex as "I" and "you" to see this;
just think about my car keys.  Suppose I place them in a duplicating
machine:  the keys disappear from the machine and an instant later
two copies appear, one a foot to the left and the other a foot to
the right, each precisely identical in every way to my original keys.
Which copy is my car keys?  Obviously there is no reason to favor
either of them.  Equally obviously they cannot both be my car
keys.  Conclusion:  when object continuity goes away, the notion
of unique identity goes with it.

(Incidentally, this is not an entirely abstruse point:  these issues
come up repeatedly in subatomic physics when it deals with identical
particles -- which in theory are absolutely identical in every way.
They do not have unique identities.  The reason this works is that
according to quantum mechanics it is impossible to know the locations
of particles between measurements, so there is no object continuity.)

Now, in the scenario, object continuity has been abolished, because
the copy of "you" has suddenly appeared out of nowhere.  Consequently,
the notion of unique identity cannot be applied to the copy.  The
question of whether the copy is "you" simply has no correct answer.
If you assume it does have an answer, you get trapped in an unresolvable
paradox; -- you cannot avoid violating one or another necessary
condition of what it means to be "you".

	-- Bill


