David Nyman wrote: > 2009/9/13 Brent Meeker <meeke...@dslextreme.com>: > >> You regard "doing the same computation" as a purely formal (= >> non-physical) critereon, but I think this is specious. It seems right >> because we talk about "a computation" at a very high level of >> abstraction. But when we ask what makes this causal sequence or that >> process a "computation", in contrast to other sequences or processes >> that aren't, we find that we must describe the computation as having an >> effect in the larger physical context. So to say that two physical >> processes realize the same computation is formal, but it is not *only* >> formal. It is implicitly physical too. > > Yes, of course I know it's *implicitly* physical, that's the problem. > The point is that evaluating CTM as a physical theory of mind > necessitates making the relation between experience and process > *explicitly* physical, and actually attempting this inevitably results > in a failure to discover any consistent association between specific > physics and specific experience.
That seems like a category mistake. You're asking for and explicitly physical relation between a computation and a physical process. But a computation isn't physical; the relation has to relate something non-physical to the physical - so obviously it relates the non-physical things like potential action in a context or evolutionary function to the physical process. >This is not merely unfortunate, it > is a direct consequence of the arbitrariness of physical > implementation central to the hypothesis. I don't see the problem. There are arbitrarily many computations of the same function too. Brent > > Your point about having an effect in the larger context is > unproblematic as long as it is considered from a third person > perspective. From this perspective there's no difficulty about the > physics of the realisation, since what is relevant is simply that it > fulfil the formal criteria in terms of *some* physical implementation, > no putative experiential aspect being at issue. I agree that this is > the right criterion to discriminate physical computational systems of > interest from those that are inconsequential (i.e. rocks etc.). The > point at issue with Peter, however, relates to the putatively > homogeneous experiential correlate of the heterogeneous physical > implementations, not their status as purely physical processes. We > seem to be discussing two different issues. > > Consider what motivates CTM in the first place. The mind-body problem > seems in many ways as impenetrable as ever, despite all advances in > brain science and on the wider theoretical and experimental front. > But wait a moment, we have a nice theory of computation, and we know > how to apply it to computers and their programming. We even indulge > in metaphor about the thoughts and intentions of our devices (I know I > do). Maybe that's what the mind is? Wizard wheeze! But wait again > - when we actually think about what these beasties are up to > physically in their various realisations - mechanical, hydraulic, > electronic, pneumatic - there's a whole raft of promiscuous, > uncorrelated physical processes going on down there, and none of them > much like our own wetware version. How can we get a consistent > physics of consciousness out of this? What to do? I know - it > doesn't matter! > > Great physical theory, eh? > > David > >> David Nyman wrote: >>> 2009/9/11 Flammarion <peterdjo...@yahoo.com>: >>> >>> >>>>> I'm not sure I see what distinction you're making. If as you say the >>>>> realisation of computation in a physical system doesn't cause >>>>> consciousness, that would entail that no physically-realised >>>>> computation could be identical to any mental state. >>>>> >>>> That doesn't follow because causation and identity are different >>>> The realisation could be consciousness (fire IS combustion) >>>> without causing it (fire CAUSES smoke but it not smoke) >>>> >>> So what did you mean the reader to conclude from your original >>> argument? You concluded that the realisation of a computation doesn't >>> cause consciousness. But did you also mean to imply that nonetheless >>> the realisation of a computation IS consciousness? If so, why didn't >>> you say so? And how would that now influence your evaluation of CTM? >>> >>> >>>>> This is what >>>>> follows if one accepts the argument from MGA or Olympia that >>>>> consciousness does not attach to physical states qua computatio. >>>>> >>>>> >>>> I find them both quite contestable >>>> >>> If you would risk saying precisely why, you might have a counter-argument. >>> >>> >>>>> I agree. Nonetheless, when two states are functionally equivalent one >>>>> can still say what it is about them that is physically relevant. For >>>>> example, in driving from A to B it is functionally irrelevant to my >>>>> experience whether my car is fuelled by petrol or diesel. But there >>>>> is no ambiguity about the physical details of my car trip or precisely >>>>> how either fuel contributes to this effect. >>>>> >>>> One can say what it is about physical systems that explains >>>> its ability to realise a certain computation. One can't say that >>>> there is anything that makes it exclusively able to. Equally >>>> one can explain various ways of getting from A to B, but >>>> one can't argue that there is only one possible way. >>>> >>> The point at issue is not whether there is only one way to realise a >>> computation, or to get from A to B. The point is that in the case of >>> the journey, the transition from physical irrelevance to relevance is >>> at the point where the physical result emerges as identical - i.e. as >>> the same journey form A to B. In the case of the computation, no such >>> physical identity of result ever emerges; all you have is a collection >>> of heterogeneous physical processes, each merely *formally* identical >>> to a given computation. It is a further - and physically entirely ad >>> hoc - assumption that this heterogeneity of physical states is >>> homogeneous with a single experiential state. >>> >>> >>>>> Yes, I agree. But if we're after a physical theory, we also want to >>>>> be able to give in either case a clear physical account of their >>>>> apprehensiveness, which would include a physical justification of why >>>>> the fine-grained differences make no difference at the level of >>>>> experience. >>>>> >>>> THat would be because they make no computational difference, >>>> if CTM is correct. >>>> >>> If all you have to offer is circular arguments we shall simply go >>> round in circles. >>> >>> >>>>> I can only suppose that complete arbitrariness would be a random >>>>> association between physical states and mental states. This is not >>>>> what is meant by arbitrary realisation. What is meant is that the >>>>> requirement that a physical system be deemed conscious purely in >>>>> virtue of its implementing a computation rules out no particular kind >>>>> of physical realisation. Consequently a theory of this type is >>>>> incapable of explicating general principles of physical-mental >>>>> association independent of its functional posit. >>>>> >>>> It isn't. Why is that a problem? >>>> >>> The problem is that theories which aren't reducible to fundamental >>> physics don't warrant consideration as physical theories. This is >>> amply demonstrated by the fact that, when reduced to a physical >>> interpretation, CTM is in fact shown to entail gross implausibilities. >>> >>> >>>>> Yes, but the upshot is that CTM is reduced to the theory that >>>>> conscious states can be associated with material systems only in a >>>>> manner that ex hypothesi must obscure any prospect of a general >>>>> reduction of their detailed material causes, because any such causes >>>>> could only be specific to each realisation. >>>>> >>>> You can have as many material details as you like >>>> so long as they are relevant to explaining the computation. >>>> >>>> Maybe you are hung up on causes. CTM is really an identity theory-- >>>> mental >>>> states are identified with functional states. It's not fire-causes- >>>> smoke causation. >>>> >>> I'm fine with mental states being identified with functional states. >>> The problem is one functional state reduces to multiple physical >>> states. Hence CTM entails that one experiential state reduces to >>> multiple physical states, without being able to give any consistent >>> physical, as opposed to formal, criterion for such identity. >> You regard "doing the same computation" as a purely formal (= >> non-physical) critereon, but I think this is specious. It seems right >> because we talk about "a computation" at a very high level of >> abstraction. But when we ask what makes this causal sequence or that >> process a "computation", in contrast to other sequences or processes >> that aren't, we find that we must describe the computation as having an >> effect in the larger physical context. So to say that two physical >> processes realize the same computation is formal, but it is not *only* >> formal. It is implicitly physical too. >> >> Brent >> > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. 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