Bruno Marchal wrote:
On 04 Jul 2015, at 02:27, Bruce Kellett wrote:
so every physically distinguishable history is automatically included.
We don't need to worry about summing over computations that go through
our particular conscious state, or which have inconsistent extensions
(white rabbits). We have only to see ourselves as instantiated in the
calculation that instantiates our universe (and us in it).
Well UDA is an explanation why this cannot work, or if you prefer, can
only work by a use of a god-of-the-gap argument.
You replace the wrong explanation "God made the universe" by the
non-explanation "There is a universe/or special universal number".
The UDA explains why your approach cannot work -- and that quite
directly. Since the dovetailer must, by definition, include the complete
set of computations that constitute the observable universe, anything
else is superfluous. The fly in the ointment, as it were, is the fact
that as well as containing our universe, the UD contains every other
possible universe that can be computed. And these additional universes
cover all of Tegmark's levels -- universe with different initial
conditions, universes with different parameters, universes with
different physical laws, and all in all possible combinations, each
repeated an infinity of times.
You might recognize this -- it is just Tegmark's computable universe
(CU) hypothesis. And it is inherent in the UD as you have given it.
Unfortunately, this renders your program of trying to recover physics
from self-referentially correct extensions of personal consciousness
impossible. Because all possible physics and initial conditions are in
the UD, you can never select out just one physics, one universe -- you
just jumble them all up and nothing consistent could ever emerge.
You might call this a "god-of-the gaps" or some such, but it is not
really that. It is just a demonstration that your approach cannot
succeed. You can't explain physics in this way; at the moment we would
have to say that if the CU hypothesis is correct, then our universe is
just a given, and no deeper explanation is possible. The universe is
just a 'brute fact', it is what it is.
Unless you equate your brain with the entire physical universe/number,
you need to soleve the FPI problem. In fact you must still show that
this solve the measure problem.
There is no longer any measure problem, and FPI is no more complicated
than the fact that we can't predict the future with certainty.
Comp really does not explain any useful detail about consciousness. And
given that it is guaranteed to fail to 'explain' physics, we might
wonder why we should bother with it.
I think, on balance, that the difficulty of the mind-body problem is
greatly overrated. It is a most only a conceptual or philosophical
problem. Since the mind supervenes on the physical brain, and both are
the product of biological (and physical) evolution, the details of
understanding this process are firmly in the realm of empirical science
-- it is basically an engineering problem.
Bruce
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