Stathis Papaioannou wrote:
> Brent Meeker writes:
>
>
>>>>> If every computation is implemented everywhere anyway, this is equivalent
>>>>> to the situation where every computation exists as a platonic object, or
>>>>> every computation exists implemented on some computer or brain in a
>>>>> material multiverse.
>>>>
>>>> But if implementing a particular computation depends on an observer, or a
>>>> dicitonary, or somesuch, it is not the case that everything implements every
>>>> computation unless it can be shown that evey dictionary somehow exists as
>>>> well.
>>>
>>>
>>> The computation provides its own observer if it is conscious, by definition.
>>
>> I'm always suspicious of things that are true "by definition". How exactly does
>> an observer provide meaning or whatever it is that makes a computation? And how
>> does consciousness fulfill this function. I, in my conscious thoughts,
>> certainly don't "observe" the computation that my brain performs. In fact my
>> thoughts seem to spring from nowhere more or less spontaneously in coherent
>> trains or as prompted by perceptions.
>
>
> Let's not try to define consciousness at all, but agree that we know what it is
> from personal experience. Computationalism is the theory that consciousness arises
> as a result of computer activity: that our brains are just complex computers, and
> in the manner of computers, could be emulated by another computer, so that
> computer would experience consciousness in the same way we do. (This theory may be
> completely wrong, and perhaps consciousness is due to a substance secreted by a
> special group of neurons or some other such non-computational process, but let's
> leave that possibility aside for now). What we mean by one computer emulating
> another is that there is an isomorphism between the activity of two physical
> computers, so that there is a mapping function definable from the states of
> computer A to the states of computer B. If this mapping function is fully
> specified we can use it practically, for example to run Windows on an x86
> processor emulated on a Power PC processor running Mac OS. If you look at the
> Power PC processor and the x86 processor running side by side it would be
> extremely difficult to see them doing the "same" computation, but according to the
> mapping function inherent in the emulation program, they are, and they still would
> be a thousand years from now even if the human race is extinct.
>
> In a similar fashion, there is an isomorphism between a computer and any other
> physical system, even if the mapping function is unknown and extremely
> complicated.
I don't see how there can be an isomorphism between any two systems. Without some
structural constraint that seems to throw away the "iso" part and simply leave a
morphism.
>That's not very interesting for non-conscious computations, because
> they are only useful or meaningful if they can be observed or interact with their
> environment. However, a conscious computation is interesting all on its own. It
> might have a fuller life if it can interact with other minds, but its meaning is
> not contingent on other minds the way a non-conscious computation's is.
Empirically, all of the meaning seems to be referred to things outside the
computation. So if the conscious computation thinks of the word "chair" it doesn't
provide any meaning unless there is a chair - outside the computation. So it is not
clear to me that meaning can be supplied "from the inside" in this way. I think this
is where Bruno talks about "the required level of substitution" and allows that the
level may be the brain at a neural level PLUS all the outside world. So that within
this simulation the simulated brain is conscious *relative* to the rest of the
simulated world.
>I know
> this because I am conscious, however difficult it may be to actually define that
> term.
But do you know you would be conscious if you could not interact with the world?
That seems doubtful to me. Of course you can close your eyes, stop your ears, etc
and still experience consciousness - for a while - but perhaps not indefinitely and
maybe not even very long.
> The conclusion I therefore draw from computationalism is that every possible
> conscious computation is implemented necessarily if any physical process exists.
That would seem to require mappings that are not isomorphisms.
> This seems to me very close to saying that every conscious computation is
> implemented necessarily in Platonia, as the physical reality seems hardly
> relevant.
It seems to me to be very close to a reductio ad absurdum.
Brent Meeker
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Received on Thu Sep 07 2006 - 00:23:24 PDT