Re: Bostrom Paper

From: Bruno Marchal <>
Date: Fri, 4 Apr 2008 13:15:41 +0200

Hi Günther,

I make a quick comment on Bostrom's paper.
For the others, I sum up Bostrom's question. Bostroms ask if two
physically identical brain entails two identical consciousness
experience or only one. He called "duplication thesis" the thesis
saying that two identical brains generates two identical experience,
and he called "unification thesis" the thesis that two identical brain
generate only one experience. I think that the paper is a bit unclear
on identity criterion for both brains and experiences. But if you
accept the physicalist (or near physicalist) background, I think that
his defense of his duplication thesis is valid, and that the epistemic
inferences he makes from comp and his duplication thesis are valid too.
But the UD Argument undermines the whole approach and some of his
fractional account of experiences (although I should think a bit more
on this to be sure). In particular, by putting the measure on the
histories generated by the UD (and not on the OMs or the instatneaous
state) then his duplication thesis can be seen as a consequence of the
computationalist hypothesis, as his epistemic inferences.
So yes, it is a good paper, despite the context used and despite the
(rather unclear) supervenience thesis presupposed. The (unclear)
supervenience thesis in used is not coherent with the consequence of
the computationalist hypothesis. But a careful reading of his paper can
help to understand the seven first step of the UDA. Now a good
understanding of the UDA should make clear all this, and I will not
A pity he does not refer to UDA, given that Bostrom has followed my
talk in Brussels at the consciousness ASSC meeting in Brussels, ...
where Chalmers quit the audience at the third step of UDA. Chalmers
seemed not to accept the subjective or first person comp
And Chalmers should (unless he has changed his mind) to be troubled by
Bostrom's paper too, but this is made plain in the paper.

Let me quote a passage of Bostrom:

<<Recent cosmological data indicate that our universe is
quite likely infinite and contains an infinite number of galaxies and
Moreover, there are many local stochastic processes, each one of which
has a nonzero
probability of resulting in the creation of a human brain in any
possible state.2 Therefore, if the universe is indeed infinite then on
our current best
physical theories all possible human brain-states would, with
probability one, be
instantiated somewhere, independently of what we do. But we should
surely reject
the view that it follows from this that all ethics that is concerned
with the experiential
consequences of our actions is void because we cannot cause pain,
pleasure, or
indeed any experiences at all. It is much more plausible to hold that
even if the
universe is the way it now seems to be, we can still influence what
experiences there
are. Since this would be impossible on Unification, we should accept

This is not an argument, but wishful thinking. The reason why ethics is
preserved despite all experiences occur, is that they occurs in a
relative way (a bit like realtive quantum state a-la Everett), and this
relatively to infinities of computation (in the complete UD deployment,
which I often called UD*). Some histories are relatively rare or many.
Of course to show this you have to solve the first person white rabbit
comp problem.


Le 02-avr.-08, à 20:20, Günther Greindl a écrit :

> Dear List,
> I searched through the archive, this paper does not seem to have been
> discussed.
> Quantity of Experience: Brain-Duplication and Degrees of Consciousness
> If two brains are in identical states, are there two numerically
> distinct phenomenal experiences or only one? Two, I argue. But what
> happens in intermediary cases? This paper looks in detail at this
> question and suggests that there can be a fractional (non-integer)
> number of qualitatively identical experiences. This has implications
> for
> what it is to implement a computation and for Chalmer's Fading Qualia
> thought experiment. [Minds and Machines, 2006, Vol. 16, No. 2, pp.
> 185-200]
> It raises some issues the UDA is concerned with.
> What do you think of it?
> Best Regards,
> Günther
> --
> Günther Greindl
> Department of Philosophy of Science
> University of Vienna
> Blog:
> Site:
> >

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Received on Fri Apr 04 2008 - 07:17:20 PDT

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