Re: Bostrom Paper

From: Russell Standish <>
Date: Fri, 4 Apr 2008 07:36:06 +1000

Not the paper, but certainly the thought experiment has been
discussed on this list, and its impact on the notion of measure. I
vaguely recall it was Hal Finney and Wei Dai and perhaps some others -
given that they are acknowledged by Bostrom at the end of his paper,
perhaps they can comment further.

I had a quick read of the paper last night, and my first impressions
is being a bit underwhelmed by Bostrom's analysis.

The first thing I take objection to is the possibility that two brains
can be kept in lockstep after the links between them are removed. Real
brains have synaptic noise, and I beleive this noise is essential to
conscious function.

In the thought experiment, after the brains are prepared in an
identical state, they can only be kept in an identical state by
maintaining a one-to-one link between the neurons of each brain. Once
even one neuron is decouple from its counterpart, the brains' physical
states will diverge. Once sufficient neurons are decoupled, the
brains' mental states will also diverge. With fully decoupled brains,
divergence is rapid, at least on the timescale of seconds, if not
faster (quantum decoherence time).

Plus we must consider the implications of this picture in a block
Multiverse - every conscious configuration exists somewhere in the
Multiverse, moreover it must exist infinitely often. Duplicating a
brain does not increase its measure, and after a very brief period of
time, it is the brain of a different person (albeit sharing a name and

So this would put me in Bostrom's Unification camp, AFAICT, and I
fail to see the validity of his reasoning for accpeting the
Duplication position.

As for Chalmers' fading qualia, no fading qualia will be experienced. This
is a direct consequence of quantum immortality. Either one experiences
full consciousness as one's brain is slowly turned into silicon, or
one experiences the evil scientist giving up for some reason while you
brain is still mostly carbon-based. In a sense, this becomes a
subjective experimental test of functionalism, in the same sense that
Tegmark's suicide experiment is a test of the many worlds.

On Wed, Apr 02, 2008 at 08:20:41PM +0200, GŁnther Greindl wrote:
> 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,
> GŁnther
> --
> GŁnther Greindl
> Department of Philosophy of Science
> University of Vienna
> Blog:
> Site:
A/Prof Russell Standish                  Phone 0425 253119 (mobile)
UNSW SYDNEY 2052         
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Received on Thu Apr 03 2008 - 17:36:36 PDT

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