On 8 June 2015 at 05:08, Bruno Marchal <[email protected]> wrote:
>
> On 07 Jun 2015, at 18:35, John Clark wrote:
>
> On Sat, Jun 6, 2015 Bruno Marchal <[email protected]> wrote:
>
> >> An event is just a place and a time; are you saying that mathematics is
>>> incapable of handling 4 coordinates?
>>
>>
>> > Of course, applied mathematics exists, and you can represent event in
>> mathematics, but you shopuld not confuse something (a physical event) and
>> its mathematical representation.
>>
>
> I am not confusing that but I think sometimes you might be confusing a
> physical thing with the language (mathematics) the descriptive
> representation of the thing is presented in. Or maybe not, maybe you're
> right and mathematics is more than just a language and is more fundamental
> than physics; nobody knows including you.
>
> Nobody can know. But we can reason from hypothesis. With the
> computationalist hypothesis, the immateriality of consciousness is
> contagious on the possible environment. Nobody pretends this is obvious,
> especially for people stuck at the step 3.
>
> The question being asked is, why hypothesis best explains consciousness?
Comp attempts to take the default materialist assumption, that
consciousness is a (very, very complicated) form of computation, and to
derive results from that assumption.
Hence what I've called comp1 is the default materialist hypothesis (also
known as the strong AI thesis, I think) - this is more or less equivalent
to the idea that a computer could, given a suitable programme and
resources, be conscious. From this Bruno attempts to show, via a chain of
reasoning, that the computations involved have to take place in
arithmetical reality ("Platonia"). This conclusion I call comp2. The task
of anyone who disagrees is simply to show that comp2 doesn't follow from
comp1.
There are various ways to try to show this. One is to doubt the starting
assumptions ("comp1"). The starting assumptions include the idea that
simple arithmetic exists independently of mathematicians - that 2+2=4 was
true in the big bang, for example. The universe appears to obey certain
bits of methematics to high precision, or alternatively you could say that
various bits of maths appear to correctly describe the behaviour of the
universe and its constituents to high precision. So that is the "which
comes first?" question, which as you correctly say we can't know (indeed we
can't know anything, if "know" means justified true belief, apart from the
fact that we are conscious, as Descartes mentioned). So one can doubt comp1
by doubting either that consciousness is a computation, or that maths
exists independently of mathematicians.
Then one can doubt the steps of the argument. I personally find little to
doubt, assuming comp1, until we reach step 7 or 8, or whichever step is the
MGA. (There has been a lot of heat about pronouns, but as far as I can see
this hasn't made a dent in the arguments presented.)
So the other main point of attack is at the comp2 end, so to speak, with
the MGA. There is Brent's "light cone" argument, which IMHO seems
unconvincing because one can make a "cut" between a brain and the world
along the sensory nerves - this is basically saying that a person could be
a brain in a vat, and never know it. But it also fails if one can in theory
have an AI, because an AI is by hyopthesis a digital machine and could
therefore could be re-run and given the same inputs, and due to the nature
of computation would have to repeat the same conscious experiences. And
then that description falls foul of Bruno/Maudlin's argument about leeching
away the material support for the computation until it is turned into a
replayed recording. At this point we can use "Russell's paradox" - sorry, I
mean argument - that a recording of such complexity may indeed be
conscious. The MGA seems to hand-wave a bit about this whole process - like
the Chinese room, we "simply" record the activities of the processing
devices and then "simply' project the movie onto the system, and so on,
leaving aside the Vast size of the envisaged apparatus. Nevertheless, if we
assume comp1 then we assume by hypothesis that a recording isn't conscious
(only a computation can be conscious, according to comp1). So that's really
a comp1 objection.
So the question in the end is which is the most reasonable hypothesis. How
does materialism explain consciousness? How does comp explain the
appearance of a material universe?
Over to you.
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