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Why reductive explanations of consciousness must fail

  1. Dec 15, 2003 #1


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    "At the end of the day, the same criticism applies to any purely physical account of consciousness. For any physical process we specify there will be an unanswered question: Why should this process give rise to experience? Given any such process, it is conceptually coherent that it could be instantiated in the absence of experience. It follows that no mere account of the physical process will tell us why experience arises. The emergence of experience goes beyond what can be derived from physical theory.

    Purely physical explanation is well-suited to the explanation of physical structures, explaining macroscopic structures in terms of detailed microstructural constituents; and it provides a satisfying explanation of the performance of functions, accounting for these functions in terms of the physical mechanisms that perform them. This is because a physical account can entail the facts about structures and functions: once the internal details of the physical account are given, the structural and functional properties fall out as an automatic consequence. But the structure and dynamics of physical processes yield only more structure and dynamics, so structures and functions are all we can expect these processes to explain. The facts about experience cannot be an automatic consequence of any physical account, as it is conceptually coherent that any given process could exist without experience. Experience may arise from the physical, but it is not entailed by the physical.

    The moral of all this is that you can't explain conscious experience on the cheap. It is a remarkable fact that reductive methods - methods that explain a high-level phenomenon wholly in terms of more basic physical processes - work well in so many domains. In a sense, one can explain most biological and cognitive phenomena on the cheap, in that these phenomena are seen as automatic consequences of more fundamental processes. It would be wonderful if reductive methods could explain experience, too; I hoped for a long time that they might. Unfortunately, there are systematic reasons why these methods must fail. Reductive methods are successful in most domains because what needs explaining in those domains are structures and functions, and these are the kind of thing that a physical account can entail. When it comes to a problem over and above the explanation of structures and functions, these methods are impotent.

    This might seem reminiscent of the vitalist claim that no physical account could explain life, but the cases are disanalogous. What drove vitalist skepticism was doubt about whether physical mechanisms could perform the many remarkable functions associated with life, such as complex adaptive behavior and reproduction. The conceptual claim that explanation of functions is what is needed was implicitly accepted, but lacking detailed knowledge of biochemical mechanisms, vitalists doubted whether any physical process could do the job and put forward the hypothesis of the vital spirit as an alternative explanation. Once it turned out that physical processes could perform the relevant functions, vitalist doubts melted away.

    With experience, on the other hand, physical explanation of the functions is not in question. The key is instead the conceptual point that the explanation of functions does not suffice for the explanation of experience. This basic conceptual point is not something that further neuroscientific investigation will affect. In a similar way, experience is disanalogous to the élan vital. The vital spirit was put forward as an explanatory posit, in order to explain the relevant functions, and could therefore be discarded when those functions were explained without it. Experience is not an explanatory posit but an explanandum in its own right, and so is not a candidate for this sort of elimination.

    It is tempting to note that all sorts of puzzling phenomena have eventually turned out to be explainable in physical terms. But each of these were problems about the observable behavior of physical objects, coming down to problems in the explanation of structures and functions. Because of this, these phenomena have always been the kind of thing that a physical account might explain, even if at some points there have been good reasons to suspect that no such explanation would be forthcoming. The tempting induction from these cases fails in the case of consciousness, which is not a problem about physical structures and functions. The problem of consciousness is puzzling in an entirely different way. An analysis of the problem shows us that conscious experience is just not the kind of thing that a wholly reductive account could succeed in explaining."

    - excerpted from "Facing Up to the Problem of Consciousness," by David Chalmers
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  3. Dec 15, 2003 #2
    Chalmers once said: The easy problems of consciousness include those of explaining the following phenomena:

    -the ability to discriminate, categorize, and react to environmental stimuli;
    -the integration of information by a cognitive system;
    -the reportability of mental states;
    -the ability of a system to access its own internal states;
    -the focus of attention;
    -the deliberate control of behavior;
    -the difference between wakefulness and sleep.

    I just have one question. How would this correlate with the undeniable existance that some organisms are subjects of experience and that cognitive systems engage in visual and auditory information-processing, while qualia and other emotions avoid ambiguity of the "consciousness" of an organism?

    I know Chalmers discussed this before but I can't remember where or when. The only thing I could think of was Chalmers discussing "the subjective aspect is experience. When we see, for example, we experience visual sensations: the felt quality of redness, the experience of dark and light, the quality of depth in a visual field. Other experiences go along with perception in different modalities..."

    Can you help? Or speak for him?
  4. Dec 15, 2003 #3


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    I'm afraid I don't quite understand the question. Rephrase?
  5. Dec 15, 2003 #4
    Let me try again.

    The initial question is basically: How would these seven problems correlate to, let's say, an organism. Since organisms aren't really cognitive systems and don't really 'hold' in visual and auditory informational processing -- how would organisms fit into these simple concepts of consciousness?
  6. Dec 15, 2003 #5


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    [?] Why aren't organisms cognitive systems? The term does not need to refer exclusively to organisms (it can refer to, say, a robot as well), but for the most part, when we talk about cognitive systems we mean organisms or functional cognitive principles exhibited by organisms. Easily the paradigmatic case of a cognitive system is the common human being. Humans exhibit all of the cognitive qualities in the list you provide by Chalmers-- that's the only reason they've been nominated at various points as possible 'essences' of consciousness in the first place.
  7. Dec 16, 2003 #6
    First off, Chalmers is indeed doing what the vitalist skeptics did before. He's saying that we can just reduce it to more and more physical processes, and never get to the experience part. Well, Daniel Dennett's intentional stance of heterophenomenology allows for those physical processes to be the experience and many scientists are coming up with hypotheses that work just as he predicted (William Calvin and Gerald Edleman are just two examples...they've each written a few very good books, and I highly recommend them, btw).

    Secondly, in the case of the vitalists, which Chalmer's himself denounces (while, IMO, basically doing exactly the same thing they did), it was discovered that the physical processes really were life. There is no more to life than the things that biology has uncovered. However, before they uncovered it, it was assumed that there must be some non-physical (spiritual) aspect that accounted for the "life" part of the being, since physical explanations had not yet yielded a satisfactory understanding. Why so many philosophers of the mind fall for this same trap is beyond me, but he himself (Chalmers, that is) exposed it as fallacious, and I say he's doing the same thing.

    Lastly, are there any books by Chalmers that I might read to further understand his views?
  8. Dec 17, 2003 #7


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    Mentat, I get the idea that either you didn't read the excerpt very closely, or you just don't like what it has to say. Either way, I expected better from you. All of your counterpoints are anticipated and explicitly rebutted in the original post, so rather than make bald assertions, you will need to counter the already detailed counter arguments to make any progress.

    From the excerpt:

    How is it that activity in the visual cortex accounts for the experience of the color red? There is an explanatory gap here, and it won't go away by simply ignoring it, as it seems is the strategy of Dennett.

    I'm surprised that this is your position, since the last 3 paragraphs of the excerpt explicitly rebuts every one of your objections, and you have done nothing here to analyze or critique the actual rebuttal. Get back to me on this one.

    I am still familiarizing myself with Chalmers, but I highly recommend two papers of his I have read:

    Consciousness and its Place in Nature
    Facing Up to the Problem of Consciousness

    His homepage, with many more materials, is at http://www.u.arizona.edu/~chalmers/
  9. Dec 17, 2003 #8


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    Why shouldn't it? In other words, by what method have we eliminated the idea that any such complex physical patterns are indeed conscious? It looks like consciousness, it acts like consciousness, what more is there?

    In short, a circular argument. We assume experience as a property that is outside of the physical, and lo and behold! We find experience as a property that is outside of the physical!

    Why not?
  10. Dec 18, 2003 #9
    But Dennett's intentional stance does not "ignore" the issue, it provides a way out from the seeming problem, by showing that it needn't be a problem at all. Basically, Dennett said what any scientist would say to the vitalists if any still exist: There is no explanatory gap, there is simply a process, and this process is life, it does not "produce" this mysterious phenomenon.

    No, it attempts to. I read that part very carefully, and all I saw was vitalism re-visited. He says:

    Can you not see the ridiculousness of this last claim? Does he honestly believe that the vitalists believed that "life" was just a physical phenomenon and would remain a mystery simply because we'd never be able to explain all of its functions?!? Not at all, they probably made statements exactly like his last one, but were proven wrong anyway.

    I'll check 'em out when I have time :smile:. Thanks.
  11. Dec 29, 2003 #10


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    The "more" is the subjective experience (or lack thereof) on the part of the system in question. Objective observation of behavior can give us clues as to underlying subjective experience, but in the end it is all speculation fueled by analogy to one's own direct experience of consciousness.

    False positives and false negatives (is that the term I'm looking for?) are not hard to come by. People with blindsight might objectively appear to have complete subjective visual experience, but in some areas of their visual fields, they in fact do not even though they can interact coherently with objects in their blind spots. Likewise, someone in a coma may appear to be unconscious but may in fact have some conscious experience. So behavioral analyses are insufficient to get a true grasp on the presence or absence of consciousness, not to mention the quality of consciousness, even if they serve as a useful heuristic for most 'normal' cases.

    The only reason behavioral analyses of consciousness work in the first place is because we can juxtapose someone else's behavior (including, importantly, verbal reports) with the behavior we ourselves associate with our own conscious experiences. One might call this method of understanding consciousness "objective judgement by way of comparison to subjective experience." If you erase the "by way of comparison to subjective experience" from the equation, as would be done in a purely physical explanation in terms of structures and functions, you have erased the entirety of your understanding of the relevant phenomenon-- you know all about heads but nothing about tails, so your knowledge of the coin is incomplete. This is especially problematic when the phenomenon you want to investigate is tails.

    Because you can explain physical structures and functions all you want and you still have not explained the whole picture. Take the typical argument: imagine a colorblind neuroscientist N in the far future who has complete knowledge of the structures and functions of the human brain. In spite of his complete objective knowledge, he still does not have the whole account: he does not know what it is like to see the color red. Now imagine that N has an operation that cures his colorblindess-- he learns something new about consciousness, above and beyond the objective facts about the structures and functions of the brain.

    edit: Stated more generally and eloquently by Chalmers--
    "Recall the main conceptual distinction between the easy and hard problems. The easy problems - explaining discrimination, integration, accessibility, internal monitoring, reportability, and so on - all concern the performance of various functions. For these phenomena, once we have explained how the relevant functions are performed, we have explained what needs to be explained. The hard problem, by contrast, is not a problem about how functions are performed. For any given function that we explain, it remains a nontrivial further question: why is the performance of this function associated with conscious experience? The sort of functional explanation that is suited to answering the easy problems is therefore not automatically suited to answering the hard problem."

    from http://www.u.arizona.edu/~chalmers/papers/moving.html
    Last edited: Dec 29, 2003
  12. Dec 29, 2003 #11


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    If there is no explanatory gap, try to explain to a colorblind person what the color red looks like by telling him all about the visual processing centers in the brain.

    There is a key distinction to be made in the two cases. Explaining life involves explaining objectively observable phenomena; explaining consciousness involves explaining subjective experience, which is not objectively observable.

    In the case of vitalism, the explanandum is one of structure and function: how is it that organisms can move about, grow, reproduce, etc? Vitalists could not see how physical explanations could account for these objectively observable structures and functions, so they posited the existence of the non-physical spirit. Once the structures and functions of life were shown to be explainable in physical terms, the explanatory posit of the spirit was no longer needed and was discarded.

    In the case of consciousness, the explanandum itself is not one of structure and function (if it were, a colorblind person could learn all about the color red simply by reading up on neuroscience). We cannot readily discard the part that is not about structure and function in this case, since it is not an explanitory posit, but rather the thing to be explained. So explaining consciousness purely in terms of physical structures and functions of the brain is not an amenable step in the right direction, it is an outright denial of the issue at hand.
  13. Dec 30, 2003 #12
    You can't, because no man can be made to experience something simply by having it explained to them, and the intentional stance doesn't require that. The intentional stance simply dictates that, when one does experience the color red, the experience is completely explainable as processes of the brain (and, if you were capable of reaching into the brain with a probe that could excite just the right neurons, in just the right fashion, you would produce the very same experience).

    Unless the intentional stance is correct, in which case subjective experience is objectively observable, you just have to know what to look for.

    But a person who isn't colorblind can't know anything more about it than a person who is...the only difference is that one has experienced it, and the other hasn't (and if you could excite the other's brain just right, that other would experience it).

    This seems to me to be a mystic denial of science's abilities. If the intentional stance turns out to be the way to go, then science will indeed be able to explain consciousness purely in terms of physical structures and functions.
  14. Dec 30, 2003 #13
    Just to be clear: The intentional stance doesn't dictate that the neurologist should be able to detect some part of the subject's brain that is shaded red, for that particular experience; instead it shows that the subject couldn't see such a shading either, and the experience must thus be an illusion of belief (belief also being a function of the brain).
  15. Dec 31, 2003 #14
    This does not address Hypnogogue's (or Chalmer's) point. You say that the experience of red is explainable as a brain process. But if you look closely at what is being explained, which is a subjective experience, that makes no sense. Physical reductionism does not cross the explanatory gap, as Hypno says. Nor does 'hetero-phenomenology'.

    First person experience is not objectively observable. This is why it is called first person experience. All that can be observed is physical behaviour. As someone said, forgotten who, digging into the brain to look for consciousness is just as useful as digging into the Earth to look for gravity. It's making a category error.

    You acknowledge that there is a difference then?

    Ifs and buts. Are you sure you've understood the 'intentional stance'? It's not an explanation of consciousness. Could you outline what you mean by it.
  16. Dec 31, 2003 #15


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    I don't think this debate can ever be settled, because the Chalmers wing is into the non-falsifiable "Naw, that's not it either" mode of denial. Whatever biologists discover, whatever capabilities future AIs develop, they will still be saying, "Since you can't convey red in words, you can't explain human conciousness completely". Even a complete listing of every neuron and action that constitutes seeing red, even a computer that can see colors and discuss them in a Turing test won't satisfy them.

    The Chalmers wing don't think they have to prove consciousness is more than what is explained, they just want to demand that scientists prove that it isn't.
  17. Dec 31, 2003 #16
    That was pretty much my point, about how this mystic viewpoint is the enemy of scientific discovery...it was in the days of the vitalists, and it is now.
  18. Dec 31, 2003 #17
    But, if one can redefine "subjective experience" as a physical process of the brain, then why should there be an explanatory gap at all?

    But subjective experience cannot exist seperate of the physical processes of the brain...in the first place, if it wasn't physical, then it couldn't interact with the physical; also, if exists seperately of the functions of the brain, in any way, then there must be something inside the head that observes these phenomena...that's asking for a homunculus.

    A difference between explaining it and experiencing it? Of course. There's a difference between explaining life and experiencing it too.

    The "intentional stance" is basically a scientific principle, stated in philosophical terms, it is the anti-mysticism. Basically, if something meets all of the physical qualifications for a particular phenomenon, then the phenomenon is occuring. If something meets all of the physical qualifications for life, then it is alive, and there is nothing metaphysical to add to it. If something meets all of the physical qualifications of being conscious, then it is conscious, and there is nothing mystical to add to it.

    This is the gist that I've gotten from Dennett's explanations of the intentional stance.
  19. Dec 31, 2003 #18


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    But by that argument, how can you justify the way you take for granted that anyone else is conscious? When the colorblind man is healed, how can you say that he is in fact healed at all, without using structures and so on? And so, without understanding of the idea of red, how can you say that the man knows what the colour red feels like?
  20. Jan 1, 2004 #19
    I think you've got it bang on. Those who think that consciousness involves first person experience want to see first person experience explained, and not just swept under the carpet by science in the way it was for most of the the 20th century. It's perfectly obvious that an experience of red is a different thing to a bunch of neurons, we should accept that and move on.
  21. Jan 1, 2004 #20
    If one could redefine 'subjective experience' as a physical process then you'd be right. Unfortunately you can't. That's why they're called subjective experiences. Some diehards are still trying but nobody has succeeded, and they never will. They are different categories of things. Science attempted to do what you have suggested for most of the 20th century. Yet here we no further on than William James was 100 years ago.

    Can you prove that?

    Yes, these are some of the difficult problems to be solved.

    This is not correct. The intentional stance is a perspective on behaviour, a way of predicting it and interpreting its causes. It can be applied to the behaviour of people, thermostats or lightening bolts. Fundamentally it is much the same stance as that taken by Watson and Skinner and other behaviorists, jazzed up a bit. It says that beliefs and representations are real only to the extent that they can be infered from an agents behaviour by a third-person. It is a 'black box' approach to mind, an approach now largely discarded by science.

    What are the 'physical qualifications' for being conscious? As far as I know nobody knows what these are.

    This is not what Dennett says as far as I can tell. He says that if one assumes that an agent is conscious, and also that the agent is rational, and also that the agent has beliefs which affect its behaviour, and then finds that, by taking the intentional stance, one can predict the agent's behaviour, then one can assume that beliefs and representations are physical. If that sounds daft it isn't my fault.

    It is tempting to think that anyone as clever as Dan Dennett must have a good point when they write books about a topic. However you can't take this for granted. Academia is a funny place. Dennett covers his tracks well when he's writing, but if you strip away the complexity and get down to basics his ideas are not new and don't make much sense. This conclusion is not just mine, it is widely held. Do you know of any philosophers who agree with him? I haven't found any, but then there's lots I haven't read.
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