Stathis Papaioannou wrote:
> Brent meeker writes:
> 
> 
>>>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.
> 
> 
> The definition of the structural constraint is part of the isomorphism. Some 
> isomorphisms are 
> more economical than others, but there are no God-given isomorphisms or 
> structural constraints. 
> The limiting case is simply a lookup table mapping any arbitrary system to 
> another arbitrary 
> system. That this is inelegant does not make it invalid.
> 
> 
>>>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 don't think it is right to say that the brain is *conscious* relative to 
> the environment. It is 
> intelligent relative to the environment, whether that means able to 
> communicate with another 
> conscious being or otherwise interacting with the environment in a meaningful 
> way. Although 
> we deduce that a being is conscious from its behaviour, and you can only have 
> behaviour 
> relative to an environment, only the being itself directly experiences its 
> consciousness. This is 
> the 3rd person/ 1st person distinction. 
> 
> 
>>>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.
> 
> 
> 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.

>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.

  >>>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.

Brent Meeker

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