On 01 Oct 2015, at 07:10, Bruce Kellett wrote:
On 1/10/2015 12:44 am, Stathis Papaioannou wrote:
On 28 Sep 2015, at 12:26 AM, Bruce Kellett
<[email protected]> wrote:
It's possible that there are no copies of you, but it seems
implausible. There would have to be infinite copies of other
things, but not you. What makes the non-copied configurations
special?
Nothing. It is just that they are a priori as likely as any other
configuration.
In an infinite random sequence of numbers it is possible that my
phone number appears once and never repeats, while other eight
digit sequences appear multiple times; but I wouldn't bet on it.
An infinite random sequence of digits has certain well-defined
probabilistic properties. In particular, ll digits are equally
likely, and all sequences of any particular length are equally
likely. If that were not so, the sequence would not be random. So
your phone number will occur many times. But this is not a good
analogy because it relies of the definition of a random sequence of
digits. We do not have any comparable uniformity definition for a
collection of universes.
But there is for the computations, as the existence (in arithmetic) of
the universal dovetailing illustrates.
And even if you are duplicated as Tegmark suggests, so that there
are many copies far outside our O-region, or even our particle
horizon, then there is absolutely no possibilitiy of any
interaction between these copies, so their existence or non-
existence can have no effect on you, so they are irrelevant -- in
principle, not just FAPP.
They cannot interact with each other, but they are
psychologically continuous with each other.
That is a meaningless assertion. Can you suggest any operational
way in which you could establish the truth of such an assertion?
Are you suggesting that psychological influences can travel
faster than light? Objects outside our Hubble volume cannot now
interact with us; objects outside our particle horizon can never
have interacted with us and can never do so in the future. The
expansion of space makes these interactions impossible.
Psychology is not exempt from these physical facts.
It follows from the meaning of the words "psychologically
continuous". If I have the same psychological properties as I did
yesterday then I am psychologically continuous with my yesterday
self. It is nonsensical to assert that yes, I remember everything
I did yesterday, I have the same personality that I did yesterday,
the same cognitive abilities that I did yesterday, etc., but I am
not actually psychologically continuous, because there has been
some sort of physical discontinuity. In fact, it is reflecting on
this that should make it clear that physical change is irrelevant
to psychological continuity except insofar as the physical change
makes a psychological difference. If you feel the same, look the
same, behave the same etc. today as you did yesterday but you are
informed that advanced aliens performed a procedure X on you in
your sleep, then that means that whatever X was, it did not affect
psychological continuity.
That is irrelevant to the point being made. I was talking about
purported copies far outside our present particle horizon -- beyond
any possibility of physical influence either way. I contend that
applying the words "psychologically continuous" in this context is
simply meaningless. Psychological continuity is dependent on
physical continuity -- even if only in the transfer of a memory
stick from one computer to another. If there is no physical
interaction of any kind, particularly if such interaction is
physically impossible, then the two persons are different, and have
nothing other than a chance resemblance. Nothing that happens to one
can have any effect on the other.
Consequently, I maintain that the idea of psychological continuity
over and above physical continuity is meaningless.
It is coherent with your idea that computationalism is false.
The situation then is just like that with the disjoint worlds
of the MWI in QM: the separate worlds are disjoint -- non
interacting -- so their existence has no bearing on you or your
future. In fact, Susskind and others have identified Tegmark's
level I multiverse with the MWI of quantum mechanics. I think
this identification is nonsense, but the relevance of the
potential copies is the same in both cases -- zero!
It is not zero if you could be any of the copies.
It is generally held that there is no difference in the empirical
predictions of the various interpretations of QM, so some
physicists consider it is a waste of time even thinking about it.
They have a point.
Demonstrate to me how this makes an operational difference. If it
makes no measurable or operational difference, then, the
relevance of the copies is precisely zero.
There is one difference between the MWI and other interpretations,
revealed through the quantum suicide experiment, but this can't be
used to gather evidence to convince anyone else.
Whether the idea behind the quantum suicide notion makes any sense
is debatable. But, as you say, it is not a way in which one can
gather empirical evidence one way or the other, though the absence
of people 10,000 years old tends to count against the idea.
There is reason to believe that in fact the universe is
infinite and uniform; but if it is not, which is possible, the
conditional argument still stands. So, do you think you would
experience the world differently if there were infinite copies
of you and of every possible variation of you?
No. Not that I believe that there are such copies, but even if
there were, they would be of zero consequence for anything
whatsoever.
What would it mean for probability if your mind were spread over
infinite copies?
Nothing, because it would make no operational difference to
anything -- even if such a concept made any sense at all.
You have IIRC said that there is a problem defining probabilities
in an infinite multiverse. Given that we observe certain
probabilities, what does this mean for the hypothesis that we are
living in a multiverse?
Nothing much. Probabilities are simply the result of ignorance -- we
don't know what the outcome will be, so we gather evidence from the
outcomes in previous similar cases and calculate the chances. We do
not have this facility in the many worlds scenario since we only
ever have evidence from one world.
Many worlds is nothing more than a hypothetical construct. There is
no concrete evidence one way or the other. And science goes with the
evidence -- in the absence of any evidence we have to say that we
simply do not know. Many worlds ideas are not without their
problems, so it is by no means clear that such scenarios have any
intrinsic advantage. If the worlds are non-interacting, as almost
certainly is the case, then they have absolutely no consequences for
psychology or the problem of consciousness.
The worlds and the computations does not need to interact to have a
role, they can interfere statistically, and they do when they extend
consistently our personal relations with respect to our probable
ennvironment.
Science follows evidence, but there are no evidence that there is a
primitively ontological world. For the many dreams, it follows from a
reasonable hypothesis in cognitive science togeteher with a reasonable
hypothesis in mathematics (Church-Turing thesis).
Bruno
Bruce
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