Bruno Marchal wrote:
On 25 Jun 2015, at 14:27, Bruce Kellett wrote:
Bruno Marchal wrote:
My job was just to show that comp entails immaterialism,
And in that you have failed. MGA does not do it.
Where? Keep in mind that "comp entails immaterialism" is what MGA
provides the exact nuance we have to add. You can save materialism by
endowing something nobody can observe with magical ability to select
consciousness. Your statement is a bit nonsensical, without telling me
to which non computable process is involved.
I don't know that comp is true, but I don't know that comp is false either.
In fact, nothing does it, because nothing that you have ever mentioned
requires the prior assumption of primitive materialism.
?
It is made explicit at step seven. You need this to have a notion of
concrete universal dovetailing running in the universe.
No. Steps 0 to 7 assume, implicitly or explicitly, the existence of a
physical universe. And you say explicitly in a number of places that it
is not part of your brief to deny the existence of the physical
universe. The question is whether it is primitive or emergent. None of
the argument in steps 0-7 depends on this physical universe being
primary -- all that is required is that it exists.
In step 7 you claim that if the UD is run in a sufficiently robust
universe, "physics, as the 'correct' science for the concrete relative
predictions must be given by some measure on our consistent relative
states. .... Physics has been reduced to computer fundamental psychology."
But there is a catch here. You have introduced the word "must" without
any justification. Even if the UD is run in a robust universe, or in
Platonia, it might well emulate all of physics in some sense, but this
does not mean that the physical universe is emergent rather than
primitive. The fact that one can compute something, or emulate it, does
not mean that it does not exist independently. There is no entailment
here. Or else computer models of weather systems would create real
cyclones and kill real people.
That is why you go on to step 8 and the MGA. But, as discussed
extensively, this argument fails. It is, at best, an argument from
incredulity, and at worst incoherent. The scenario is that you replace
the activity of the conscious brain by a recording of that activity by
removing physical neurons and connections one by one, while replacing
their activity by projections from the recording. Is consciousness
retained in this process? Your assumption would seem to be that it is
not, because if it were, it would imply that the recoding is conscious,
at least while being played back in these circumstances. And you find
this absurd.
But the alternative does not establish the required result either. If
the brain ceases to be conscious as the connections are removed --
either gradually or with the loss of some critical number of connections
-- then the hypothesis of physical supervenience is substantiated. If it
remains conscious (even though simply replaying a previous conscious
experience) even when only the recording playback remains, then physical
supervenience is still substantiated, because the recording is every bit
as physical as the original brain connections. In the "Yes, Doctor"
argument, you are agreeing to have your brain replaced by an emulation
on a physical computer. I doubt that even you would agree for the doctor
to remove your brain and replace it with a universal number tattooed
on your forehead.
Note, again, that the MGA, even while it fails, is not dependent on any
notion of primitive physicality -- the argument would still run even if
the physical is wholly emergent from some more fundamental stratum. MGA
is just a failed argument. And your claim than comp *entails*
immaterialism collapses in a heap of illogic.
Bruce
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