Saturday, September 10, 2011


It is ironic that the last comment on the blog was one I made three months ago now (6/12/11) in response to the first posting on the blog a year ago by Bob French, "Apparent Distortions in Photography and the Geometry of Visual Space." Bob did not respond to my comment but did visit UCSD and gave a fine presentation to the members of the Center for Brain and Cognition on the geometry of visual space July 27th (which, alas, was under attended).

We seem to be left with three theoretical contretemps:

(1) a geometry of visual space that either changes or is under determined by empirical data

(2) a theory of perception (the "causal theory") that cannot be reconciled with the topological and metric attributes of visual space as related to any part of the visual system, whether peripherally in the eyes, or centrally in the brain

(3) dualism provides no solution to the requirements of geometrical congruence as I stated in my 1985 paper "Visual Space as Physical Geometry"

Though this forum has provided an unusually rich exchange of both traditional and novel ideas, like many blogs it seems to have run its course, perhaps not so much because the contributors have nothing more to offer, but because I don't think most were willing to really question fundamental assumptions, instead holding to theories based on metaphysical or abstract ideas, even when challenged or contradicted by logic, observation, and experimental findings. Ultimately that results in an impasse, and discussion ceases--and philosophy and science are the worse for it.

Hopefully one of you or someone new will throw down the gauntlet and restart the dialog...

-Bill Rosar


  1. I agree with Bill that there is more to say and hopefully others will join in the discussion. To get a bit of a dialogue going, I did want to say a few things on the concept of intersubjectivity since I think that it is a crucial concept whose coherence is presupposed by much of the rest of the discussion, and since that coherence has been questioned by Bill.
    As I see it the issue of the coherence of the concept of intersubjectivity is intimately connected with the issue of the knowledge of other minds. I also agree with Bill that there is an asymmetry between knowledge of our own conscious mental states (where access to these states is immedate) and anything like knowledge (if "knowledge" is the right word here, and it isn't if certainty is built into the concept) of the conscious mental states of others. In any event, I am symapathetic with the inductive argument by analogy for anything like knowledge of the conscious states of other persons, i. e., inferring those states of other persons because they possess similar bodies which have similar origins to mine. Admittedly this is an inductive argument and does not give conclusive evidence, but I think that it is the best that we can do. We can then compare introspective accounts of these conscious states, and that is the basis of intersubjective judgments as I see it.

  2. Thanks for that, Bob. Intersubjectivity is a word I do not personally use, certainly not in the context of perception or the stated topic of this blog, in which subjectivity never crops up at all to my knowledge. So I would discount your claim that it is presupposed.

    If you want to talk about intersubjectivity, it might be useful to first see how the concept was intended by the phenomenologists who coined it (Husserl?) and how it is relevant and connected to the problem of studying visual space and its structure, except perhaps to the extent that people are able to communicate with each other--which, I should think, is too general a concern to be of much relevance here.

  3. I believe that you are right Bill that the concept of intersubjectivity was introduced by Husserl, I believe in the Cartesian Meditations. Also, Husserl, despite what he says about the "epoche" or bracketing of ontological issues in doing phenomenology, ends up endorsing idealism, while I do not and thus there are some fundamental differences between us.
    As we have noted before both "objective" and "subjective" have multiple meanings, but the relevant ones here appear to be of the object and of the subject. I think that visual space is in the subject (part of a person's consciousness) whereas I take it that you think that it is in the physical object being perceived, and thus, as you say, you do not need the concept of "subjectivity" in discussing visual space.
    Interestingly, if subjective judgments are shared, as implied by calling them "intersubjective" then they may also be "objective" in the sense that there is common agreement about the answers. One final point is that I thought that you were questioning the very internal coherency of the concept of the "intersubjective" and I don't see that your preceding remark addresses this issue, since instead you seem to be merely questioning whether we need to use the concept in talking about visual space.

  4. Of course subject and object are abstractions, and in the concept of visual space and the perceptual world, I suppose they correspond roughly to the perceptual body within the perceptual world, respectively. So in that context, talk of the subject refers to what we ordinarily call "our body" or, as Smythies would say, the "self" within it. We do not talk of the things we see as being "subjective" at all, but use object language instead. I don't say that it is my subjective impression that the sky is blue, for example, or that it is my subjective opinion that the Empire State Building is tall, etc.

    So this is largely why I believe that the phenomenological concept of the intersubjective is useless in this context and even confusing. To me, the concept seems to be trying to make the subjective objective, and that strikes me as a contradiction in terms (thus the very term itself "inter-subjective" seems like an oxymoron). It is the term that I find defective, not the question of other minds, which can be discussed in different perfectly acceptable terms found in ordinary language, as Moore and Wittgenstein argued.

    I am now working on a new tack: that there is problem with the notion of "directness" in the critique of direct realism in terms of the representative theory of perception.

  5. I believe that Husserl uses the concept of the 'subject' in talking about 'intersubjectivity' to be referring states of the conscious mind and not the body, since as I noted he was an idealist. Although I am not an idealist I agree with him on this point. Intersubjective judgments then involve comparisons among different conscious minds, and may be 'objective' to the extent that there is agreement about these judgments. I agree that the multiple meanings in use here can be confusing but I don't see a contradiction since different usages are involved. I also agree that in effect any demonstrations about intersubjectivity basically come down to comparisons of verbal introspective reports, and thus there is a gap there with the experiences themselves.

  6. I'm not sure where you want to go with the discussion of intersubjectivity, Bob, because "agreement between subject reports" is the sine qua non of experimental psychology in general. Have I missed something?

  7. Hi Everyone,

    In a week I will read a paper at the "Psychology and the Other" conference, in Cambridge, MA (See, where the governing question is, can we really know the mind of another person, and if so, how?

    The conference will be heavily populated by psychotherapists and as an empirically oriented contributer, I may be booed off the stage.

    My paper may be found at

    There is a link there to the full text. The summary is: Intersubjectivity is not merely an assumption about the other’s state of mind, a deduction from behavior and circumstance, nor a neurological expression. Rather, intersubjectivity is the human ability to participate in the subjective state of the other. Philosophers who accept such a definition, such as Husserl, Levinas, Sartre, and Buber, describe the phenomenon, but provide little or no accounting of how it arises. They simply take intersubjectivity as a phenomenological given. Some psychologists, such as Freud, Piaget, and Kohlberg, acknowledge developmental processes for intersubjectivity, but are biased to a nativist view. This paper suggests that intersubjectivity requires intense, lifelong socialization, and where that process fails, the adult is psychologically deficient. Awareness of the role of socialization in intersubjectivity illuminates the wide range of intersubjective sensitivity in adults and children.

    I hope this paper provide some helpful input in the context of Bob French's recent comments on intersubjectivity. Although Husserl began his definition of intersubjectivity with an embodied perceptual argument, he insisted that it was not a deduction from perception but a phenomenological given.

    Bill Adams

  8. Many thanks, Bill, for sharing this with us.

    Of course intersubjectivity has been a popular buzzword both in the social sciences and in the humanities for quite a while now, and has thus been used so widely (and perhaps loosely) that I think one must almost define what they mean by it when using the term for any precise purpose.

    To the extent that it can be linked to the philosophical problem of "other minds," I understand the concept behind it. I just have trouble with the very word itself, because it seems to be almost an oxymoron (like "military intelligence"). It implies a sense of the word "subjective" or "subjectivity" that is, in some sense, "public," and that tends to do violence to whole notion of subjectivity more broadly construed. In some sense something is either subjective or objective, and how that distinction which really has no middle term is then bridged is what bothers me.

    Nonetheless the existence of empathy is indeed a phenomenological given, as immortalized by Bill Clinton's comment, "I feel your pain."

    It has been argued that empathy, for one, is very highly correlated with what Heinz Werner called "physiognomic perception," a primitive and developmentally early mode of perception that is attuned to expression and expressive attributes (like facial expressions). We know that animals can also be very "sensitive" not only to each other's feelings, but to ours, so the core of so-called intersubjectivity is probably not confined to primates--nor is altruism, which seems closely linked, as we know.

    Rama has proposed that mirror neurons are a likely basis for empathy, in that they fire in response to the sight, for example, of someone else being touched, rather than oneself being touched. In our biological ancestry this may have not only been an important component of social bonding, but also played a role in hunting animals, as hunters seem to have an uncanny way of "tuning into" their prey, something that has often been discussed by anthropologists in terms of "sympathetic magic."

    My sense of things is that the whole notion of subjectivity needs a much fuller conceptual analysis to avoid certain paradoxes (contradictions in terms) that have plagued philosophers for decades if not centuries, e.g., really knowing what other people are thinking or not, etc.

    Can we find a way of bringing intersubjectivity back to the topic at hand--visual perception? Culbertson argued, for example, that with special connection devices between brains we could literally see through other people's eyes--but that remains in realm of science fiction, though Professor Quatermass is able to do it with special equipment in the film "Quatermass and the Pit"!

  9. I think the discovery of mirror neurons provides a solid neurophysiological basis for the long-standing cognitive idea that we have within us something like an "internal model of the world," and that can be extended to include other people and their minds. This is probably why we can "second guess" others.

    Surely there must be socialization involved, but the mechanisms of generating this "internal model" can perhaps also be defective, as in the case of autism and psychopaths, both of which have major deficits in empathy.

  10. Dear Bill:
    You say: (3) dualism provides no solution to the requirements of geometrical congruence as I stated in my 1985 paper "Visual Space as Physical Geometry'.
    However, I have just finished reading this paper, and I find in it no substantial discussion about dualism at all! Rather (as you criticise others for unwarranted metaphysical prejudices), you mention dualism only on page 418, and then only to mention it as somehow completely unacceptable, as beyond some limit of consideration.

    So tell me: what do you think IS the best theory for the geometry of visual space, and where is that space? Have you come to any positive conclusion?

  11. Thank you, Ian! Personally I do not believe in substance dualism, but am inclined more and more to believe in old-fashioned body-soul dualism which, if I am not mistaken, is really the initial idea behind all dualism.

    While it is hard to make it a scientific idea, there is now an immense corpus of anecdotal evidence that the soul leaves the body at death--and sometimes during life, in so-called astral projection. The skeptics who try to reduce this to the behavior of a dying brain surely cannot explain the latter, because the astral traveler's brain is alive.

    Clarifying my summary position statement (3) above, I should have included the qualifier "dualism provides no *geometrical* solution to the requirement of geometrical congruence," i.e., it offers no account of congruence nor how congruence relations are defined between brain and visual space.

    Simply claiming as John Smythies has for 60 years that perceptual space occupies another space-time continuum than that of physical S-T does not solve the problem of why brain structures are not congruent with those in visual (perceptual) space, because it provides no mapping between the two (both a geometrical and topological transformation in this case) that would relate the two.

    At present all we can assert is an ostensible causal relation between the two: When the visual cortex is destroyed, all vision for the individual ceases completely--such individuals don't even see blackness: they see nothing, or, differently put, they don't see at all (at least that is what Smythies and I have gleaned from the neurology literature).

    However, I have countered that all we can really say is that visual space is no longer connected to the individual percipient, because it requires a brain in order for it to be connected. I think the logic of causality has forced the theory of perception to paint itself into a corner, and I think only Culbertson thus far addressed the problem with his own rather odd theory of conscious perception (which is non-dualistic).

  12. Hi Bill,
    I do not understand the navigation on this site well enough to locate where you have been having browser problems. Sorry.

    As for intersubjectivity, we have, in this discussion an interesting case of what Kuhn called incommensurable paradigms. We are simply unable to communicate because of pre-theoretic assumptions that avoid scrutiny. It is an odd thing, among intellectuals, to run up against brick walls such as this. In the spirit of discussion however, I will make one more attempt to communicate some basic points, responding to your comments above.

    1. Your thinking on this matter is deeply Cartesian, in that you divide the world into a) the living, personal, mental, subjective and b) the insentient, spatial, perceptually objective domains. The paradigm of intersubjectivity rejects/eschews/transcends that dichotomous thinking. Intersubjectivity is, in fact, a case of quasi-public subjectivity, exactly what Cartesian thinking cannot accept. The (partially) public nature of intersubjectivity is exactly the innovation that is revolutionizing psychological thinking about mind, self, and world.

    As a corollary, you seem to also be wedded to the Aristotelian logic of the excluded middle: A thing cannot be both A and Not-A simultaneously. But that traditional logic must be put aside to understand a hybrid phenomenon like intersubjectivity, where self and not-self are not clearly bounded and not mutually exclusive. If a person is unwilling or unable to put in abeyance pretheoretic commitment to Cartesian and Aristotelian thinking, there is no chance of understanding intersubjectivity.

    2. The research in mirror neurons does not support the idea that empathy/intersubjectivity is caused by, or determined by neurology. The argument is circular, as it presupposes intersubjective understanding of behavioral gestures in order to make that explanation. In addition, the mirror neuron activity is observed after, not before, the intentional behavior sample, so cannot possibly be causal. Also, neurological epiphenomenalism as an explanation of mental phenomena is self-refuting, nihilistic, and incoherent, so not helpful. These points are made in detail elsewhere, as referenced in my paper cited earlier.

    3. Bringing the topic of intersubjectivity back to the theme of the structure of visual space is done with this hypothesis: the structure of visual space is a social co-construction, a tacit, intersubjective agreement among people in a shared culture. Comparisons between phenomenal visual experience and physiological or mathematical optics, for example, cannot be fruitful without appreciation of the intersubjective consensus that constitutes phenomenally appreciated visual space.

    Hope that is helpful, although I already know it isn't.

    Bill Adams

  13. Many thanks, for this, Bill, but I would counter that your remarks demonstrate how intersubjectivity fails, because I do not holds the views you are ascribing to me, in that I am not committed to either a Cartesian view nor am I falling prey to the excluded middle. In fact, I hold very few pre-theoretic assumptions of this sort, as should be evident by the unorthodox views I have expounded here on the blog in many posts. To the contrary, I have explicitly urged contributors to question every assumption they hold (myself included). If anything I have simply argued from different perspectives, and by countering the notion of intersubjectivity with what may seem like a Cartesian position, it is only that, and by no means represents my own personal view.

    At bottom I see this as a problem of language—at least the problem I have been attempting to identify with the very term “intersubjective” itself. After all, the word "subjective" and the noun "subjectivity" formed from it are words, and they are words that have several different senses. OED lists 7 senses for “subjective” and “subjectivity” has 4. Those different senses are not interchangeable, and clearly the notion of intersubjectivity rests upon a sense (or senses) of “subjective” that is not incompatible with subjectivity being in some sense “public,” or more formally, “objective.”

    When I say there is no middle term, that is not a logical argument but a fact of language, i.e., in the sense that either something is subjective or objective. Intersubjectivity suggests that this is not so, but other than the term itself, offers no remedy to explain the violation of ordinary usage. That is because there is no middle term between subjective and objective in our language, and beside that, “intersubjective” seems to have been promulgated to suggest a relationship between subjects that is predicated upon circumventing a Cartesian view, otherwise there would be no need for the term at all.

    G.E. Moore and Charlie Broad both felt that the problem of other minds (if not called by that name) was a pseudo-problem, and strenuously argued that we can know perfectly well what other people are thinking or feeling *in some sense.* But it is that sense that is hard to formulate without self contradiction and violations of linguistic usage. That is my only point here and why I don’t like the term, which I believe is confusing, because as I said above, it tends to suggest an oxymoron. There is no need for the term in my opinion, because it seems to be trying to bridge two different senses of the word “subjective” which results in equivocation.

    In referring to mirror neurons I was merely pointing to the fact that our very bodies seem physiologically geared to empathy, not that I was reducing empathy to neurophysiology as you suggest, Bill. How often have I faulted neuroreductionism here? You are preaching to the choir.

  14. This comment has been removed by a blog administrator.

  15. Hopefully this message will go through since I have been having some problems posting. Also, I have been away from the blog for a few weeks since I was preparing for a talk on quantum entanglement that I gave this past Wednesday to the physics dept. at the Univ. of Maryland Baltimore County. I thought that the talk went surprisingly well considering that it rejects special relativity.
    I did want to make a few comments on intersubjectivity. As I have said before I think that there is at least an epistemological asymmetry between our knowledge of our own subjective conscious mental states, which we have immediate knowledge of, and our knowledge (if this is the right term) for knowledge of the conscious states of others which is indirect. Idealists, such as Husserl and Brentano, may not have a problem here, but I think that they have a problem avoiding solipsism without going into convolutions.
    I have more of a problem though with materialists such as Chisholm, and I take it Searle, who help themselves to Brentano's concept of "intentionality" for referring to our immediate awareness of the physical objects of perception without realizing that there is a causal gap here for a materialist theory of perception.

  16. Thanks, Bob. My response, though, is "so what"? Do we really need to enter into a discussion of the nature of subjectivity (or intersubjectivity) to advance the discussion of visual space? Is it not sufficient to assume that each of us has a visual space for our purposes here, and that others not so fortunate who have suffered brain damage do not?

  17. I think perhaps Bill that the difference between you and me on "intersubjectivity" is mostly one of emphasis, perhaps I think that its watered-down sense is somewhat more useful than you do. We appear to have a deeper disagreement on the location of visual space since you hold that it is outside the head of the observer, as does Culbertson, while I think that it is inside. If Bill Adams is in fact holding a version of idealism, which is the way that I read his comments, then I have a deeper disagreement with him. Is my reading right? In any event I am glad that some others are joining in on the discussion.

  18. I am hoping that Bill Adams may elaborate on why we should be talking about intersubjectivity in connection with visual space, and thus how it is specifically relevant to our topic. At present that is not clear to me, but perhaps I am being obtuse. I think much more to the point are those factors that define subjecthood perceptually, something that has already been discussed here previously.

    Science has not identified the location of visual space. It has not been observed empirically in any way to be inside someone's head, only that it is causally linked to brain processes. But so is the heat generated by neuronal metabolism that radiates through the skull and scalp outward from the body that can be imaged through infrared photography. There is no scientific proof that perceptual space is in the brain. Worse, it is not clear how it is even possible to prove that it is in the brain, especially given the violation of geometrical self congruity, which I have stressed (i.e. any figure is congruent with itself). The existing neuophysiological evidence shows that brain events are not even geometrically similar to the geometrical structure of visual space, let alone congruent with it.

    The problem with Culbertson's theory is that it doesn't make sense physically, and I told him so. All he challenged was the assumptions that visual space was in the brain, without offering a viable theoretical alternative. I think it is arguable that visual space is neither in the head nor outside it. Smythies' alternative was to put it in another space-time system, but as I have stated above, that does not solve the problem of geometrical congruence, which is the sine qua non of geometrical identity as he himself realized already back in the 1950s.

  19. I would also like to hear from Bill Adams, in particular on whether he holds a variant on idealism. I agree with you Bill that science cannot tell us the location of visual space, and thus anything we say here is conjectural, although hopefully also backed up by reasons. If neural correlates to consciousness exist in the brain, and if we deny the existence of action at a distance, it seems to me most plausible to say that visual space is located in the brain as well, but I admit this rationale is not completely conclusive.

  20. I, too, hope that Bill Adams will continue to participate and wonder if he may hold, for example, a version of idealism similar to that of Schelling?

    But either we must question the causal theory of perception (or details of it) or reject the requirements of geometrical congruence to assert that visual space in the brain. Take your pick.

  21. Now that I can finally get through, I should like to point out there is a third alternative. One can deny that visual space is in the brain. And why not? The "standard assumption" that it is in the brain is based on the assumption that the adequate and sufficient processing of visual information goes on in the brain. Since modern neurology shows this idea to be false, there is no reason to say visual space is in the brain. Where is it, then? What the wisest men would say, I do not know, but I think I must say it exists only within the mind's awareness of sensory impressions, and in this way only as a "mental construct." I would follow Aquinas and Augustine to say the soul goes on from the bodily functioning (in this case, what processing there is in the brain) and develops such awareness with its distinctive features. What has to be remembered here is that visual experience, like all mental life, belongs to the person, which is body and soul together for a human subject.

    As for what Robert said, may I say it is a little surprising. If we deny the existence of action at a distance? Well, but he and I have discussed what quantum physics has to say on this very point!

  22. As for the the causal theory of perception, what is required for this theory as it feeds into classical realism is that experience correspond appropriately to perceivable objects, based on being causally derived from those objects, and only that. The idea of correspondence involved may or may not be excessively problematic, as has been discussed before in other postings. But if this idea can be made out, then only the conscious experience at the end has to correspond to the objects. Nothing says that what happens inside the person along the way must also correspond to the objects in anything like the same way. To be sure, what happens along the way with perceptual mechanisms (eyes, brain, et cetera) must of course preserve the relevant information. But all this takes is appropriate functional organization. No basis of reconciling topological and metric attributes is needed. So yes, some details of the causal theory of perception must be rejected, but only those details based on assuming sensory experience is fully developed within the brain.

  23. Welcome back, David! Nothing pleases me less than carrying on a monolog, which is why activity on the blog ceased for a while, because once Bob stopped replying, it would have only been me talking (lately I have been talking to myself enough as it is).

    The philosophical work that needs to be done really entails some house keeping (or cleaning), because much as some neuroscientists would like to believe visual space is in the brain, the only evidence for localizing it there comes from a wholly unique causal relationship: That which exists between one person’s conscious experience and what is held to produce that experience, which neuroscience believes is the brain. But as I have noted already, here we encounter a fundamental problem in the logic of causality, because something does not cause itself. The “double aspect theory” tried to dispose of that problem by arguing that the brain as observed by a scientist is one aspect, the other aspect being the person’s consciousness. The problem with that position is that it still tends to be neuroreductionistic, because the “objective” aspect of observing the person’s brain is given a higher reality status than the person’s consciousness which is still reduced to brain function, rather than the converse, i.e., brain function being reduced to consciousness.

    If we approach the ontological status of visual space geometrically, as has been one of my main goals here with the blog, we find that there is a geometrical conundrum, viz., the apparent geometry of visual space (or shapes in it) tends to resemble physical objects at the distal end of the optico-visual process more than it does the proximal brain end of it, contradicting that which the causal theory of perception would predict, i.e., congruence.

    So the causal analysis leads to a different conclusion that the geometrical one, the geometrical analysis suggesting just the opposite: As we move backwards through the visual system, indeed ultimately outside it completely, we find geometrical congruence between visual percept and object. One main reason for that is that the splitting of the visual input in half by the eyes—or “doubling” of it by them—is never corrected in the brain through rejoining, given that half the visual field is represented in one hemisphere, and the other half in the other hemisphere—so that never the twain shall meet. This suggests to me that the causal theory of perception is partly or even wholly false. How do we make it true AND also meet the required geometrical requirement of (self) congruence?

    From the standpoint of relativity, there is another curious problem, which I mentioned here many months ago, namely, that relativity would predict that each time coordinate in someone's visual space, if it is a part of the physical space of the brain, would be infinitesimally different. Arbitrarily we could assign the time coordinate t = 1 to a central point in visual space but moving out from that radially would already create a problem because it is not clear what would fix the time coordinates in a radius around the center to all be, say, t = 2? How thus are the time coordinates synchronized into the “specious present” which, topologically defined, is an extended visual area possessing an infinitude of space-time coordinates? The visual points (presumably) are not only separated spatially from one another, but temporally. Thus for even a single infinitely small point to be conscious in relationship simultaneously to another point creates a problem for relativity. What possible could be responsible for the observed synchrony of points in one's visual space?

  24. I would also like to welcome back David McGraw. One place where your knowledge might help here David, is on the concept of substance as it relates to dualism. I see that Bill Rosar is sympathetic with a body - soul dualism which he does not want to characterize as 'substance dualism.' You have told me before that Aquinas might be sympathetic with something like this, but I think that a lot depends on what you build into the concept of 'substance.' Perhaps you could flesh this out a bit. Or to put it another way, what is it about the concept of 'substance' in 'substance dualism' which you object to Bill?

  25. Christoph Koch perhaps as much as anyone in the neurosciences today has made popular the conundrum of "how does the brain produce qualia?" as if qualia were something like an excrescence of brain function. I have always countered with the question of why the rest of the nervous system does not also "produce" qualia? There is no answer, probably because qualia are not a substance.

    If one accepts the notion that the soul leaves the body at death, the experiences that have been reported by people of that happening (as well as out-of-body experiences in the living), clearly suggest that "something" that leaves the body is also leaving the body's sensory system in some way, and continues to experience surroundings in terms of qualia. A "silver cord" has been reported as being "seen" connecting the "astral body" to the person's "physical body" and that it breaks upon death.
    For that reason it seems useful to argue a difference between the soul being a different "substance" from that of the body, but still something in the qualia world (perceptual world), or at least "represented" in the qualia/perceptual world.

    It is hard to reconcile such experiences with the perceptual world being merely a product of brain function, and suggests that it is something more than that, perhaps indeed something "objective" in some sense--thus relevant to Bill Adams' interest in the question of intersubjectivity.

  26. I guess that a lot depends upon what you build into the concept of "Substance" here Bill, since you are willing to characterize the existence of "something" in the qualia world. What is that thing lacking which disqualifies it from fitting your concept of a "substance."? It seems to me that an awful lot depends on how words are defined here, and I, at least,am willing to have a pretty broad sense of "substance" going, perhaps at least roughly as anything capable of possessing properties (either phenomenal or physical ones) and enduring through time (if you or David want to patch this up a bit be my guest).

  27. Many comments ago I gave my reasons for rejecting the idea that qualia constitute a substance, most fundamentally because they have been deliberately excluded from the picture of the world created by science. As before I would just say that if they have been excluded from that picture, why would one expect to find them then in the physical world even if they were there? And by what principle (logical or otherwise) after having been so removed from the physical picture of the world are they held to constitute a special "substance" in some other domain of existence? How do we establish that such a domain is separate from the physical world? To me it is more parsimonious to put them back in the physical picture--but we don't seem to have the means for doing that. This suggests to me a defect in the epistemology of physical science rather than a logical defect. Churchland, of course, just solves the problem by dispensing with qualia altogether!

    It seems to me that Mach was the only one who tried to erect an ontology of the physical world that was based on qualia (sensations), but people get sidetracked by his skepticism about atoms and forget about his main endeavor in this regard.

  28. Once again I was pleased to find that Ray Tallis has very nicely restated the larger issues to which I allude above in a recent lecture he gave on "neuromania":