Re: The physical world is real

From: <marc.geddes.domain.name.hidden>
Date: Sun, 23 Sep 2007 22:46:38 -0700

On Sep 23, 10:39 pm, Youness Ayaita <younes....domain.name.hidden> wrote:
> There have always been two ways to interpret the interrelationship
> between the physical world and our minds.

There's a lot more than two ways.

>The first one is to consider
> the physical world to be fundamental; from this perspective, the
> appearance of the mind is to be understood with the help of some
> neurological theory that maps physical states of the brain to states
> of the mind or observer moments.

Not neccesserily. There are several possible variations on taking the
physical world to be fundamental. Strong materialism does not map
physical states to observer moments - strong materialism - or
'eliminativism' - says that observer moments are merely a human
construct we use to describe what are really physical processs.
According to this doctrine, you can't rightly talk about observer
moments at all. What you have described above is weak materialism -
weak materialism - or property dualism - would agree that the physical
world is fundamental, but allow that observer moments are still real
'ontological primatives' which attach to (map to) the physical. See
my next paragraph below.


>The second way starts with the mind,
> denying the fundamental role of the physical world. According to this
> assumption, the physical world is introduced with the help of a theory
> of physics mapping mental states to physical states that reproduce the
> mental state within themselves. Imprecisely speaking, the second way
> questions the reality status of the physical world.


As I mentioned, there are still other possibilities. Neither of your
two possibilities is compatible with *comp*. According to comp (which
seems to be the most popular position on this list) it's the
mathematical world which is fundamental. Both the mind and physical
reality emerge from mathematics. So there's a third possibility
there.

The second possibility you mention has a long history of ignominious
failure - Idealist approaches seem to lead to mysticism mostly and
have not helped the advance of science. I think we can rule out
Idealism . I think it's got to be either *comp* (mathematics is
fundamental), or some variation on possibility 1 - at the end of the
day I'd have to go with possibility 1 - weak materialism (only
physical substances exist), but with some kind of property dualism
(additional non-physical propties can attach themselves to physical
substances - these non-physical properties supervene on - are
dependent on the physical - but are not reducible to them).


>
> Both ways allow the elaboration of an ensemble theory. The first
> approach starts from the ensemble of all physical worlds (or formally
> with descriptions thereof). The second approach uses the ensemble of
> all observer moments (or descriptions thereof). When Rolf expressed
> the idea "UTM outputs a qualia, not a universe" (which is similar to
> the second approach), I wrote: "I have always been hopeful that both
> approaches will finally turn out to be equivalent."


The third possibility (comp) starts with an ensemble of mathematical
relations , not an ensemble of all physical worlds, nor an ensemble of
all observer moments.


>
> It's a very trivial fact though that the two approaches are not
> equivalent. Nonetheless it's interesting to note it. I argue that we
> have good reasons to discard the second approach. The fundamental role
> will be assigned to the physical worlds (hence the title of this
> message). The difference between the two approaches leads to different
> expections to the question "What will I experience next?".
> Consequently it can be measured empirically. We find this result by
> observing that different physical worlds may produce the same observer
> moment (e.g. if the physical worlds differ in a detail not perceivable
> by the observer). This assigns a higher probability to the observer
> moment when chosen randomly in order to answer the question (it's
> multiply counted because it appears more than once in the everyting
> ensemble). Opposed to this, every observer moment (in the RSSA within
> a given reference class) would have an equal probability to be
> selected if we used the second approach.
>
> I think that the quantum mechanical Born rule strongly supports the
> first approach: Observer moments are weighted according to a specific
> formula. They don't have equal probability!
>
> Example: Both quantum states, |A> = |0>/sqrt(2) + |1>/sqrt(2) and
> |B> = |0>/sqrt(3) + |1>/sqrt(1.5)
> lead to the same two possible observer moments when a measurement in
> the (|0>,|1>) basis is performed. According to the Born rule the
> probabilites for the two observer moments are equal for |A> and
> different for |B>. Starting from the second approach (observer moments
> are fundamental) this result cannot be understood.
>
> If we take this result seriously, Bostrom's self-sampling assumption
>
> "Each observer moment should reason as if it were randomly selected
> from the class of all observer moments in its reference class."


> should be modified:
>
> "Each observer moment should reason as if it were randomly selected
> from the class of all observer moments in its reference class,
> weighted with their frequencies in the Everything ensemble."

No, neither Bostrom's version nor your modified version works. There
is no strong reason for believing Bostrom's self-sampling assumption
at all, as he himself admits in his detailed analysis. The problem
is that the very process of reasoning is interfering with the thing
being reasoned about (since reasoning is a thought process and so are
'observer moments'). For this reason all versions of the Anthroic
Principle are stuff and nonsense if you ask we. Reflectivity (how to
think about thought itself) is an unsolved problem in probability
theory, the solution for which is known only to me. I have no
intention of revealing that solution here however, since it's the key
to AI and my opponents are undoubtably reading my postings on this
messagelist. Suffice it to say that there needs to be a
generalization of probability theory to enable one to reason about
probablities themselves, and this requires the introduction of a
second-order number which is not itself a probability, but is a number
representing something else entirely....... :D




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Received on Mon Sep 24 2007 - 01:46:49 PDT

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