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 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~----------~----~----~----~------~----~------~--~---
