Stathis Papaioannou wrote:
> Brent Meeker writes:
>
>
>>>Maybe there is something about my brain that would render me unconscious if all outside
>>>input stopped, but that seems to me a contingent fact about brains, like the fact that I
>>>would be rendered unconscious if my oxygen supply were cut off. A hallucination is defined
>>>as a perception without a stimulus
>>
>>Not really; it may just be a perception that doesn't match the stimulus, e.g. a
>>perception of Christ brought about by hearing certain piece of music.
>
>
> In psychiatry, a misperception is called an "illusion", a perception without a stimulus is called a
> "hallucination".
That an hallucination appears to have no stimulus may be just due to our inability to
track the stimuli.
But I accept I've misused the term "isomorphism" as described below.
>
>
>>>and there are millions of people in the world who have
>>>hallucinations all the time. Sometimes people are so overwhelmed by hallucinatory experiences
>>>that you could saw their leg off and they don't notice, which is in part how dissociative
>>>anaesthetics like ketamine work. If you like, you can say that consciousness is maintained by
>>>one part of the brain interacting with another part of the brain: one part is program, the other
>>>part data, or one part is computer, the other part environment. The point is, whatever you
>>>choose to call it, an isolated physical system can experience consciousness.
>>
>>I won't insist, because you might be right, but I don't think that is proven. It may
>>be that interaction with the environment is essential to continued consciousness.
>
>
> But surely even if this is so for all brains evolved on Earth it is not logically necessary
> for every possible conscious machine.
>
>
>> >>>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.
>>>
>>>
>>>How do you define the non-isomorphic mappings?
>>
>>Consider the physical process "tick tock tick tock..." There are only two states so
>>it can be isomorphic to "1010101..." or "abababa...". But it cannot be isomorphic to
>>a process "rock scissors paper rock scissors paper..." with three states. There can
>>be a mapping between them: there can be a mapping between "1" and the content of the
>>Oxford English Dictionary, but there's no "iso" about the morphism unless there is
>>some structure that is preserved by the mapping.
>>
>>
>>>>>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.
>>>
>>>
>>>Like Bruno, I am not claiming that this is definitely the case, just that it is the case if
>>>computationalism is true. Several philosophers (eg. Searle) have used the self-evident
>>>absurdity of the idea as an argument demonstrating that computationalism is false -
>>>that there is something non-computational about brains and consciousness. I have not
>>>yet heard an argument that rejects this idea and saves computationalism. Personally,
>>>I would bet in favour of computationalism being true, but I cannot say that I am sure.
>>>
>>>Stathis Papaioannou
>>
>>I would bet on computationalism too. But I still think the conclusion that every
>>physical process, even the null one, necessarily implements all possible
>>consciousness is absurd.
>
>
> What about the idea that every possible consciousness is implemented necessarily, without
> the need for a physical substrate?
I thought that rested on the idea that every computation was realized by any physical
process whatsoever, even a null one, because there was a mapping from the physical
process to the computation. This was taken to imply that the physical basis was
irrelevant and the computations could be free standing. But if only isomorphic maps
are allowed, it may not hold, depending on what's preserved as "iso".
>In discussing Tim Maudlin's paper, Bruno has concluded
> that either computationalism is false or the supervenience theory is false.
As I understand it Bruno would say that physics supervenes on number theory and
consciousness supervenes on physics. So physics is eliminable.
Brent Meeker
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Received on Sat Sep 09 2006 - 03:05:13 PDT