Russell Standish wrote:
On Thu, May 07, 2015 at 10:45:12PM +1000, Bruce Kellett wrote:
...
I am sorry, but this just does not follow. The original physical
functionality is admitted to be still intact -- provide, admittedly,
by the projected movie, but that is still a physical device,
operating with a physical film in a physical projector, and
projecting on to the original (albeit damaged) physical machinery.
How has the physical element in all of this been rendered redundant?
The original functionality of the 'brain' has been preserved by the
movie; the conscious experience is still intact even though much of
the original functionality has been provided by another external
physical device. How does this differ from the original "Yes Doctor"
scenario in which the subject agrees to have his brain replaced by a
physical device that simulates (emulates) his original brain
functionality? I submit that it does not.
The only difference between the movie replacing the functionality of
the original experience and having that functionality replaced by a
computer would seem to be that the computer can emulate a wider
range of conscious experiences -- it is 'counterfactually correct'
in that it can respond appropriately to different external inputs.
The film, being a static record of one conscious experience, cannot
do this. But it has been admitted that the film can reproduce the
original conscious experience with perfect fidelity. And the film is
every bit as physical as the original 'brain'. So the physical has
not been shown to be redundant. It cannot be cut away with Occam's
razor after all. If it were, there would be no conscious experience
remaining.
I conclude that the MGA fails to establish the conclusions that it
purports to establish.
Thanks for this excellent summary, Bruce. The answer given as to why the film is
supposedly not conscious is that it absurd. I agree with you that it
is not, prima facie, absurd at this point. Usually, Bruno then goes on
to recount his "stroboscope argument", which is in his thesis, but not
in any English language publication to my knowledge. Essentially the
idea is that we stop the projector, take the film out and lay it down
on a very large table. Now as an observer, we can run along the table,
seeing the frames of the film in their original order, and it will be
as though the film is projected. But that would mean the conscious
moment would depend on whether the external observer is running or
not.
Thanks for you comments and clarification. I felt that, at the point
indicated, there were a couple of paragraphs missing -- something which
bridged the gap between removing the physical functionality of the
original brain and concluding that the physical brain was not necessary.
Your summary of the "stroboscopic argument above" helps fill this gap.
The argument is, as has been said, an appeal to the intuition that the
point reached is absurd. But this is a very weak link to the conclusion.
Another intuition could reach a quite different conclusion. Indeed, my
intuition does. This is because, as you have noted, the recoding on the
film does not create a new conscious moment, it merely replays one that
already existed. The recording might be timeless, but then so is the
original conscious experience if viewed as part of the block universe.
This is not to say that time is not essential for the experience, it is
just the fact that time is included in the block in a comprehensible
way. So laying the film out and viewing it by walking along means that
the sequence of brain states is replayed in real time -- the original
conscious experience is still there, but it is the *same* experience,
not something new. By extension, the film is then another timeless
record of the conscious experience, just as the trace of the original
brain in the block universe.
So the intuition that says that we have reached an absurd positon, is an
impoverished intuition.
Personally, I think the problem started much earlier, in supposing
that that recreating the exact same sequence of physical states
instantiates more conscious moments. It does not. The conscious moment
is exactly the same, and exists in that physical reality. Creating a
recording does not change that fact.
That seems to be a central observation. Such a view underlies what I
said above.
The only problem I see is if the recording were to arise by chance, by
some lucky coincidence of the random motion of molecules, without the
original computation having taken place. Then is that conscious moment
instantiated? Obviously, in a robust ontology, it is, because all
conscious moments are instantiated, but suppose the ontology is not
robust.
I don't see this as a difficulty. The random assembly of molecules might
create a conscious brain that exists for a fleeting instant and has
novel experiences. Just think of Douglas Adams and "The Hitchhikers
Guide to the Galaxy When "The Heart of Gold" exits from the infinite
improbability drive in orbit around the planet Magrathea, a bowl of
petunias and a sperm whale suddenly materialize and fall to the ground.
The whale has time for a few novel conscious moments before impact.
This is similar to the Boltzmann brain problem. Are Boltzmann brains a
problem in physics? They are for some, particularly in eternal inflation
models where the physical universe is indeed infinite. But Sean Carroll
has some interesting ideas that might get around these problems. I
certainly agree with his basic insight that quantum fluctuations do not
exist outside a measurement context, so Boltzmann brains almost
certainly do not arise.
Personally, I think the intuituion pump has simply run dry at that point. I
don't think the MGA helps.
Which was rather my conclusion. Since the MGA is not a rigorous
argument, it was always of very limited utility -- it certainly is
insufficient to carry the weight of the conclusion that the physical
substrate is unnecessary for consciousness.
Bruce
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