by David Foss
April 15, 1994
Bats, Qualia, and Knowledge
What it is like to be particular:
Nagel proposes that any purely physical account of [conscious] life could not possibly give an account of the phenomenal experience of any particular conscious being (whether extra-terrestrial, bat, or human). The reason seems to be two-fold. First, it appears that we might know everything there is to know about the world in which such a being operated, and even know all there is to know about the physiological functioning of their brain (or brain analogue), but still not have a clear sense of what it is like to be so physiologically oriented within such an environment. Indeed, it would seem that even with all the information one might be able to collect about, say the sensory apparatus of a bat, it remains beyond our conceptual capacity to even “imagine” what it is like to have such an apparatus. This point, unfortunately, rests on two unstable assumptions. The first is clearly unwarranted: limits upon our imaginative capacities (at the moment, or of necessity) do not entail limits upon either our knowledge or the matter of fact. That a hypercube (the four dimensional analogue to the familiar cube) is not imaginable in any manner other than as a two-dimensional “shadow” does not entail an ambiguous or unstable geometry (and even more exotic geometries, which clearly transcend out imaginative powers altogether are not thereby “impossible,” or even in the least bit “fuzzy”). The second, a point which will be raised again with respect to Jackson (below), is that our inability to “know” what it is “like” to be a bat does not in any obvious way rule out physicalism. It may still be the case that there is nothing more to being a person, than to be so physically constituted, oriented, and environmentally embedded. More on this latter.
Second, and more importantly for Nagel’s argument, the objection to physicalism (admittedly still an ambiguous thesis in itself) rests upon the claim that an account which strives for objectivity cannot adequately represent the phenomenon of subjectivity. It is of the essence of hearing that it be particular to a hearer. It is of the essence of an objective claim that it transcend the peculiarities of each knower. But we are apt to confuse things here. The essence of an objective claim, or a scientific claim more generally, is not so much the absence of subjects, investigators, or what not, but a sufficient degree of explicitness about the peculiarities of these [players] such that generalizations can follow. Can a general claim capture the fully nuanced “spin” of a phenomenon as experienced? It is not obvious that it cannot, or at least as obvious as it might seem if we ask the same of an “objective” claim. But this does raise some degree of concern. It seems strange to think that we can make public what appears so essentially private. And this intuition appears to be the driving force behind much of what Nagel has to say. But it does not seem thereby either conceptually, or factually, impossible.
Qualia ain’t physical information:
Jackson’s attack upon physicalism does not place as much weight upon our imaginative powers, but does return to Nagel’s point that “being in” mental state X is distinct from observing (or referring to, or identifying, etc.) mental state X. He reviews a number of arguments which purport to show that this distinction not only exists, but is relevant (and mortally damaging) to any effort which seeks to “reduce” all mental phenomena to physical phenomena.
Jackson claims that we might possess every bit of physical information about a conscious being, say Fred, and yet not know all there is to know about Fred. This is not the argument that we might know everything there is to know about Fred, but still fail to understand what it is like to be Fred. The later, I would propose, is quite compatible with at least some forms of physicalism. The former, however, asserts that there is some bit of knowledge, some fact, left out by a purely physicalistic picture. Again, this is not the claim that, ala Putnam, a review of the data at the one level may conceal regularities and relationships which function at a different level, (even where the first is more “fundamental” than or ontologically prior to the second,) such that a micro-level analysis may be unexplanatory. Rather, this is the claim that any analysis of the data, at any level, will not give a full account of Fred. I can know more about Fred than by any arrangement, or functional analysis, of all the [physical] data I can collect about him.
Examples of such “knowledge” are critical. It is said that Fred can discern between two types of red; and that this discernment is clear and distinct in the most perfect sense (at least with respect to colors). We are all, quite truly, “color blind” with respect to these two “colors.” Assuming that we could collect all the data about Fred’s optical hardware, neuro-physiological makeup, and the character of the two types of light waves he distinguished, Jackson claims that we would still know more if we could “see” the two colors as distinct. But what kind of “knowledge” is this? It may be true that I could know all there is to know (informationally) about being a slave without thereby feeling as a slave does. But does it follow that I do not know all there is to know about being a slave? A theory of knowledge which counts being a on a par with justifiably believing the truth that ß is left wanting here. And such a theory is necessary for such an objection to even make sense. There may be more to being a than knowing everything about a, but it nothing thereby follows concerning the constitution of a or knowers qua a.
April 21, 1994
Third Assignment: The Identity Theory
(Talking points for a debate)
Three preliminary topics:
1. Ontology: What is the stuff of mind? Obviously, the physicalist is committed to the view that there is but one substance, and it is physical. But it should be pointed out that there is nothing necessarily intuitive about the ontology endorsed by a pure physicalist. I am, of course, a realist about apples and oranges, about C-fibers and retinae. But the fundamental [physical] ontology endorsed by any pure physicalist is ultimately committed to the reality of quarks, atoms, molecules, etc., and the various fundamental forces enumerated by our physics. And to the extent that apples and oranges, C-fibers and retinae, are real, they are abstractions from such a material substrate. The world of the quark is, admittedly, a strange world to find more “real” than the realm of everyday objects. A world in which unseen (and unseeable, directly anyway) particles, waves, and forces interact across complex spacial geometries according to strict mathematical formulae seems far removed from any “common sense” view of the world. So a defense of physicalism cannot rest upon some intuitive preference we might have for a more “concrete” theory of the mind. Rather, a defense of such an ontology rests upon a more general conception of what should matter in our theoretical rendering of the world in which we live. And this defense takes as its point of departure the claim that predictive [and “explanatory”] power, conceptual “simplicity”, and mathematical soundness are the principle goals inherent in any theoretical model of our world. It is only a short distance from here, to the preference of a mature physics over the more general class of mentalistic or psychological “sciences”.
2. C-Fiber Stimulation “Pain”? Is the phenomenon of pain identical with a certain sort of physical structure, namely the stimulation of C-fibers? The answer is a potentially misleading “yes”. Pain is, as a matter of fact, a neurophysiological phenomenon essentially involving the activation of identifiable central-nervous system components. It may be true that C-fibers are one such component. Importantly, this does not limit the physicalist to the claim that only stimulation of those particular fibers named C-fibers in a given body, or a structural phenomenon within which this particular C-fiber stimulation occurs, (i.e., the particular atomistic implementation of certain behavioral structures) is essential to any valid ascription of pain. Rather, it is precisely the structural role, actually played, by such fibers which both makes them C-fibers and makes their stimulation essentially painful. This is not a functionalist reading of the relevance of such central nervous system activity. It is the physical structure, the set of physical relations and mechanisms instantiated by such tissue, and not the implementation of some abstract state transformations or procedural mappings of inputs to outputs, which characterizes the phenomenon of pain.
It may sound functionalist to recognize that it is the role such fibers play (in the overall functioning of the system) which forms the basis of calling them C-fibers. And that therefore, it is not directly the matter of such fibers which make their activation synonymous with (or constitutive of) the phenomenon of pain, but rather the activation of their role with respect to the [physical] system as a whole. From this it follows somewhat trivially that, for us, C-fiber stimulation is essential to pain. C-fibers are defined that way in our structural analysis. All that might change if we were to find out that in fact it is the stimulation of a-fibers, and not C-fibers, which correspond to the phenomenon of pain [for us], is that a-fibers would then be correctly understood as the appropriate structural component in whose systemic actualization consists pain (although there may be problems here in terms of the reference, sense, and meaning of terms within our physics). But this is not a strictly functional analysis of pain, because it is not the role itself which is pain or painful, but the actualization of a particular sort of structural mechanism within a particular sort of overall system. Although the relevant structural particularities may be hard to pick out, they are in principle open to empirical identification, and will most assuredly be completely described by a mature physics.
3. What is the status of our substantive mental theory, as measured against our actual, or potential, physical theory? The promise of a mature physics, as I mentioned at the end of my last answer, is important to distinguish from the physics we have today. In particular, it is likely that our present physics is not sufficiently developed to account for the full range of behavior intrinsic to the “mind”. As a result, I am something of a realist with respect to mental phenomena, even where such phenomena appear to transcend the descriptive limits of our physics as it is currently conceived. Whereas a more full-blooded eliminative materialist might be willing to dismiss any such phenomena as fictions peculiar to an archaic theory, I would consider the failure to account for such phenomena (the concepts of belief, desire, etc.) in a purely physical account a failure not of the archaic vocabulary, but an actual failure of the physics. No identity theorist claims that everything we attribute to the mental realm has a perfect analogue in the physical. And to this extent every physicalist might be called an eliminative materialist. But I do not think a physicalist need go as far as full-blown eliminative materialism, and insist that the mentalistic theory as a whole (in which desires, perceptions, feelings, etc., are expressed meaningfully, and play some explanatory role) will have to be jettisoned in order that we truly represent the matter of our minds. There may be particular concepts which will need revision or elimination. But I take it that our general theory has much of the story right.
What is an identity theory of mind?
An identity theory of the mind proposes that whatever can truly be said of the mental, is thereby truly said of the brain/central nervous system complex. Or, as David Armstrong expressed the thesis, “we can give a complete account of man in purely physico-chemical terms.” An identity theorist, variously called a physicalist or materialist, proposes simply, that mental states are physical states; mental causation is central nervous system causation; minds are brains appropriately situated in the world of physics, chemistry, and biology. The science of the mind is the science of the brain. Of course, all this may sound a bit vain-glorious with respect to the power and scope of the material sciences. But the claim is not that the physical sciences, as they are theoretically and instrumentally equipped today, are capable of delivering a fully adequate [physical] theory of the mind. Rather, the claim is that a fully adequate theory of mind, physical or otherwise, can only be delivered by a fully developed [physical] science. Our notions of what counts as physical may change along the way (recall the gradual acceptance of force-at-a-distance as a physical phenomenon), but the theory will ultimately be a thoroughly physical one.
Is this all there is to the claim of the identity theorist? It may seem that it is. It is, at the very least, the claim that our conception of mind must ultimately refer to a wholly physical phenomena. Nevertheless, there are nuances which deserve attention, especially if we are concerned with distinguishing the generic form of physicalism I have in mind here, from the relatively extreme views (still within the general fold of physicalism) of eliminative materialism, and functionalism.
It would be foolish to claim that descriptions and explanations at a micro-level are as clear or “powerful” (in terms of rhetorical persuasiveness) as functional descriptions at some macro-level. And here, it might seem that any physicalist will be something of a functionalist. However, even here, I take it that no matter how confused the picture might seem at the micro-level, there is nothing in the macro-level description which is not discernible “all the way down.” This is to say, that while a micro-level description may be cluttered with too much information (most of which is irrelevant to the description of any given macro-level phenomenon), no more information is contained in the macro-level description than can be found at the micro-level. It may be true that certain phenomena are hard to see at the micro level, but it would be false to say that they “vanish” thereby. Indeed, the advantage of a micro-level analysis will be found in terms of a greater mathematical precision with which characterizations of the whole system may be made.
Ultimately, pure physicalism attempts to bridge two rather disparate conceptual commitments: first, mental phenomena are essentially physical phenomena (isomorphic “from the ground up”); and second, mental categories are, for the most part, real (realism with respect to most mental categories). As per the first commitment, I should distinguish between systems or descriptions which are functional isomorphic and those which are operationally isomorphic. (A condition of functional isomorphism is too weak,.., whereas operational isomorphism, taken with a sufficient degree of salt, ensures the survival of most of our mentalistic intuitions.) As per the second commitment, I should address the cost of not being a realist with respect to our common sense mental categories. By insisting that these categories, and the substantive mentalistic picture, is at worst a misleading abstraction from physical phenomenon, what do we avoid?
Some preliminary [possible?] objections to the alternative forms of physicalism:
Full-blown EM gives up too much. Granted, no EM theorist is necessarily committed to a complete rejection of our mental vocabulary. But EM appears to give no added weight to the theoretical framework provided by our mental vocabulary. One then wonders, (1) where did this vocabulary come from, and (2) how are we to proceed if our present understanding is merely arbitrary?
Functionalism, insofar as it is distinct from pure physicalism, posits qualia-like phenomena.