In addition to spectrum reversal type situations, where no change is noted from 
either 3rd or 1st person perspective (and therefore it doesn't really matter to 
as you say, it may be occurring all the time anyway and we would never know), 
there is 
the possibility that a change is noted from a 1st person perspective, but never 
If you consider a practical research program to make artificial replacement 
brains, all the 
researchers can ever do is build a brain that behaves like the original. It may 
do this because 
it thinks like the original, or it may do it because it is a very good actor 
and is able to pretend 
that it thinks like the original. Those brains which somehow betray the fact 
that they are 
acting will be rejected, but the ones that never betray this fact will be 
accepted as true 
replacement brains when they are actually not. Millions of people might agree 
to have these 
replacement brains and no-one will ever know that they are committing suicide. 

Stathis Papaioannou

> Subject: Re: UDA revisited and then some
> Date: Fri, 1 Dec 2006 12:27:37 +0100
> To:
> Le 01-déc.-06, à 10:24, Stathis Papaioannou a écrit :
> >
> >
> > Bruno Marchal writes:
> >
> >> <snip>
> >>
> >>> We can assume that the structural difference makes a difference to
> >>> consciousness but
> >>> not external behaviour. For example, it may cause spectrum reversal.
> >>
> >>
> >> Let us suppose you are right. This would mean that there is
> >> substitution level such that the digital copy person would act AS IF
> >> she has been duplicated at the correct level, but having or living a
> >> (1-person) spectrum reversal.
> >>
> >> Now what could that mean? Let us interview the copy and ask her the
> >> color of the sky. Having the same external behavior as the original,
> >> she will told us the usual answer: blue (I suppose a sunny day!).
> >>
> >> So, apparently she is not 1-aware of that spectrum reversal. This 
> >> means
> >> that from her 1-person point of view, there was no spectrum reversal,
> >> but obviously there is no 3-description of it either ....
> >>
> >> So I am not sure your assertion make sense. I agree that if we take an
> >> incorrect substitution level, the copy could experience a spectrum
> >> reversal, but then the person will complain to her doctor saying
> >> something like "I have not been copied correctly", and will not pay 
> >> her
> >> doctor bill (but this is a different  external behaviour, ok?)
> >
> > I don't doubt that there is some substitution level that preserves 3rd 
> > person
> > behaviour and 1st person experience, even if this turns out to mean 
> > copying
> > a person to the same engineering tolerances as nature has specified 
> > for ordinary
> > day to day life. The question is, is there some substitution level 
> > which preserves
> > 3rd person behaviour but not 1st person experience? For example, 
> > suppose
> > you carried around with you a device which monitored all your 
> > behaviour in great
> > detail, created predictive models, compared its predictions with your 
> > actual
> > behaviour, and continuously refined its models. Over time, this device 
> > might be
> > able to mimic your behaviour closely enough such that it could take 
> > over control of
> > your body from your brain and no-one would be able to tell that the 
> > substitution
> > had occurred. I don't think it would be unreasonable to wonder whether 
> > this copy
> > experiences the same thing when it looks at the sky and declares it to 
> > be blue as
> > you do before the substitution.
> Thanks for the precision.
> It *is* as reasonable to ask such a question as it is reasonable to ask 
> if tomorrow my first person experience will not indeed permute my blue 
> and orange qualia *including my memories of it* in such a way that my 
> 3-behavior will remain unchanged. In that case we are back to the 
> original spectrum reversal problem.
> This is a reasonable question in the sense that the answer can be shown 
> relatively (!) undecidable: it is not verifiable by any external means, 
> nor by the first person itself. We could as well conclude that such a 
> change occurs each time the magnetic poles permute, or that it changes 
> at each season, etc.
> *But* (curiously enough perhaps) such a change can be shown to be 
> guess-able by some richer machine.
> The spectrum reversal question points on the gap between the 1 and 3 
> descriptions. With acomp your question should be addressable in the 
> terms of the modal logic Z and X, or more precisely Z1* minus Z1 and 
> X1* minus X1, that is their true but unprovable (and undecidable) 
> propositions. Note that the question makes no sense at all for the 
> "pure 1-person" because S4Grz1* minus S4Grz1 is empty.
> So your question makes sense because at the level of the fourth and 
> fifth hypo your question can be translated into purely arithmetical 
> propositions, which although highly undecidable by the machine itself 
> can be decided by some richer machine.
> And I would say, without doing the calculus which is rather complex, 
> that the answer could very well be positive indeed, but this remains to 
> be proved. At least the unexpected nuances between computability, 
> provability, knowability, observability, perceivability (all redefined 
> by modal variant of G) gives plenty room for this, indeed.
> Bruno
> > 

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