On Feb 16, 3:40 pm, Jason Resch <jasonre...@gmail.com> wrote:
> On Wed, Feb 16, 2011 at 9:04 AM, 1Z <peterdjo...@yahoo.com> wrote:
> > On Feb 16, 8:27 am, Jason Resch <jasonre...@gmail.com> wrote:
> > > On Tue, Feb 15, 2011 at 4:19 PM, 1Z <peterdjo...@yahoo.com> wrote:
> > > > On Feb 15, 10:12 pm, Brent Meeker <meeke...@dslextreme.com> wrote:
> > > > > On 2/15/2011 1:48 PM, 1Z wrote:
> > > > > I agree.  Although it's interesting that some people with synasthesia
> > > > > apparently perceive numbers as having various perceptual properties.
> > > > Some people "perceive" pink elephants too. However, other people don't
> > > > "perceive" them , leading cynics to suppose that they are not
> > > > really being perceived at all.
> > > The guy who reported seeing the digits of pi like a vast landscape also
> > > receited over 20,000 digits from memory.  That should lend a little more
> > > credence to his claims.
> > Which are what? I don't think *he* is claiming numbers objectively
> > exist. And isn't the fact that all synaesthetes visualise them
> > differently
> > somehat contrary to *that* claim.
> >  > Sure. Horses are real and unicorns aren't. Didn't you know that?
> > > Unless you've visited every time period in every corner of reality how
> > can
> > > you assert unicrons don't exist?
> > The same way I assert everything: the evidence I have is good enough.
> > >The fossile record might suggest they have
> > > never lived on this planet but that hardly rules out their existence
> > > everywhere.
> > > "Does XYZ exist?"
> > > "Let me look around...  I can't see it right now, it must not exist!"
> > > Instead we should take a more humble approach:
> > > "I've looked around and cannot see it here, it probably doesn't exist
> > here,
> > > however I have no idea whether or not it exists in places I cannot see or
> > > have not looked."
> > > I think Bayesian inference:
> >http://en.wikipedia.org/wiki/Bayesian_inference#Evidence_and_changing...
> > > Is particularly useful in answering questions relating to existence.  The
> > > question is, what prior probability would you set to a proposition such
> > as
> > > "Other universes not visible to us exist".  1Z and Brent would seem to
> > > assign a rather low probability, but that just means a higher threshold
> > of
> > > evidence will be required to convince them.  Lacking any evidence at all,
> > > the least biased prior probability to begin with is 0.5.  If some
> > evidence,
> > > for fine tuning for example, accumulates then you should adjust your
> > assumed
> > > probability that the proposition "Other universes not visible to us
> > exist"
> > > is true.
> > > Are you aware of a better or more fair way of addressing such a question?
> > I am a fallibilist. You are preaching to the converted.
> Okay it seems we have a common foundation we agree on.  Can you explain why
> you have confidence in the unreality of other possible universes rather than
> uncertainty?  What evidence have you seen for or against that proposition?

The  mathematical multiverse suffers from a double wammy: it is
too much (white rabbits) and explains too little (time and
consciousness are
not explained). Physical multiverses are a bit more of a nuanced
issue. Many worlds
is not my favourite interpretation of QM, but at the end of the day
there could be
empirical evidence one way or the other.

Mathematical monism is both too broad and too narrow.

Too broad: If I am just a mathematical structure, I should have a much
wider range of experience than I do. There is a mathemtical structure
corresponding to myself with all my experiences up to time T. There is
a vast array of mathematical structures corresponding to other
versions of me with having a huge range of experiences -- ordinary
ones, like continuing to type, extraordinary ones like seeing my
computer sudenly turn into bowl of petunias. All these versions of me
share the memories of the "me" who is writing this, so they all
identify themselves as me. Remember, that for mathematical monism it
is only necessary that a possible experience has a mathematical
description. This is known as the White Rabbit problem. If we think in
terms of multiverse theories, we would say that there is one "me" in
this universe and other "me's" in other universes,a nd they are kept
out of contact with each other. The question is whether a purely
mathematical scheme has enough resources to impose isolation or
otherwise remove the White Rabbit problem.

Too narrow: there are a number of prima-facie phenomena which a purely
mathematical approach struggles to deal with.

    * space
    * time
    * consciousness
    * causality
    * necessity/contingency

Why space ? It is tempting to think that if a number of, or some other
mathematical entity, occurs in a set with other numbers, that is, as
it were, a "space" which is disconnected from other sets, so that a
set forms a natural model of an *isolated* universe withing a
multiverse, a universe which does not suffer from the White Rabbit
problem. However, maths per se does not work that way. The number "2"
that appears in the set of even numbers is exactly the same number "2"
that appears in the list of numbers less than 10. It does not acquire
any further characteristics from its context.

The time issue should be obvious. Mathematics is tradionally held to
deal with timeless, eternal truths. This is reflected in the metpahor
of mathematical truth being discovered not found (which, in line with
my criticism of Platonism, should not be taken to seriously). It could
be objected that physics can model time mathematically; it can be
objected right back that it does so by spatialising time, by turning
it into just another dimension, in which nothing really changes, and
nothing passes. Some even go so far as to insist that this model is
what time "really" is, which is surely a case of mistaking the map for
the territory.

There are a number of reasons why it is unlikely that there are purely
mathematical reasonse why one mathematical structre exists, and
another does not. For one, it is well-known that existence is not a
first-order property. It is therefore possible that a Plenitude or
Platonia of all combinations of first-order properties would not
explain and second order properties. There is also the mismatch
between the tradtional contingency of existence, and the equally
traditional necessity of mathematics.

Consciousness is a problem for all forms of materialism and
physicalism to some extent, but it is possible to discern where the
problem is particularly acute. There is no great problem with the idea
that matter considered as a bare substrate can be the bearer of mental
properities. Any inability to bear mental properties would itself be a
property and therefore be inconsistent with the bareness of a bare
substrate. The "subjectivity" of conscious states, often treated as
"inherent" boils down to a problem of communicating one's qualia --
how one feels, how things seem. Thus it is not truly inherent but
depends on the means of communication being used. Feelings and
seemings can be more readily communicated in artistic, poetic
language, and least readily in scientific, technical language. Since
the harder, more technical a science is, the more mathematical it is,
the communication problem is at its most acute in a purely
mathematical langauge. Thus the problem with physicalism is not its
posit of matter (as a bare substrate) but its other posit, that all
properties are physical. Since physics is mathematical, that amounts
to the claim that all properties are mathematical (or at least
mathematically describable). In making the transition from a
physicalist world-view to a mathematical one, the concept of a
material substrate is abandoned (although it was never a problem for
consciousness) and mathematical properties become the only possible
basis for qualia. Qualia have to be reducible to, or identifiable
with, mathematical properties, if they exist at all. This means that
the problem for consciousness becomes extreme, since there is no
longer the possibility of qualia existing in their own right, as
properties of a material substrate, without supervening on
mathematically describable properties.

The interesting thing is that these two problems can be used to solve
each other to some extent. if we allow extra-mathemtical properties
into our universe, we can use them to solve the White Rabbit problem.
There are two ways of doing this: We can claim either:-

    * White Rabbit universes don't exist at all
    * White Rabbit universes are causally separated from us (or remote
in space)

The first is basically a reversion to a single-universe theory (1).
Mathematical monists sometimes complain that they can't see what role
matter plays. One way of seeing its role is as a solution to the WR
problem. For the non-Platonist, most mathematical entitites have a
"merely abstract" existence. Only a subset truly, conceretely, exist.
There is an extra factor that the priveleged few have. What is it ?
Materiality. For the physicalist, matter is the token of existence.
Maerial things, exist, immaterial ones don't.

The second moves on from a Mathematical Multiverse to a physical one
(3). The interesting thing about the second variety of non-just-
mathematical monism is that as well as addressing the White Rabbit
problem, it removes some further contingency. If the matter, physical
laws, and so on, are logically possible, then the general approach of
arguing for a universe/multiverse on the grounds of removing
contingency must embrace them -- otherwise it would be a contingent
fact that the universe/multiverse consists of nothing but

> If more evidence accumulated for Fine-Tuning, would that be sufficient for
> you to believe it is probably true that universes ruled by other laws exist
> also?

Fine tuning seems to be a dubious idea

> Do you think the prior probability that "other physical universes exist"
> should be greater than the prior probability that "mathematical objects
> exist"?  If so, why and to what degree?

That's apples and oranges. There are good armchair arguments against
Platonism, but physical multiverses are much more an empirical issue

> Finally, do you see any difference between "all possible (self-consistent)
> universes exist" vs. "all logically possible objects in math exist"?

There's no contradiction in the existence of an object
that is inhernetly unmathematical. That would be  a level V
kinds of everything.

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