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In its contemporary incarnation, the mind-body problem has attempted to distance itself from its metaphysical origins and to present itself as a scientific problem. In its new guise it is characterized by the application of methods and insights derived from psychology, neurophysiology, evolutionary biology and, lately, quantum theory. However, the problem, treated as a scientific problem, is proving a tough nut to crack. Nicholas Humphrey characterizes the present state of research as follows: . . . the various explanations that are currently on offer for how the conscious mind could achieve what it does entirely by normal physical means are hard for most laymen to understand. but they are hard too, it should be said, for many of the scientists themselves, and there is still very little agreement even among the cognoscenti about which explanations work and which do not. All but a few contemporary psychologists agree that there will eventually prove to be some sort of satisfactory monist theory of mind-brain relationships, a theory, that is, which does succeed in showing how mental activity and brain activity can be one and the same thing. But at present there really is very little consensus about the form, let alone the substance, of the theory-to-come. Some go for computer analogies, others seek the answers in complexity theory or neural Darwinism, others think it all hinges on quantum theory . . . and perhaps the one and only thing that every theorist agrees on (and being one of them I can say this without fear of contradiction) is that there is something wrong with everyone's theories other than their own. 

The result is that the 'problem of consciousness' continues to be referred to in the literature-even the scientific literature-as the one great unsolved problem of our times" (1995, 195). I would like to suggest in this paper that lack of progress may not be due to the fact that the mind-body problem is an especially hard one, but rather to the fact that it is a metaphysical problem, like free will or the existence of God, and, as such, not one that can be solved via scientific inquiry. 

Now the very fact that at present, the mind-body problem is being treated as if it were a scientific problem (after centuries in the metaphysical wilderness) provides us with an instant characterization of the relationship between scientific problems and metaphysical problems: a metaphysical problem is simply a problem to which science has not yet turned its attention. When science does turn its attention to a metaphysical problem science either solves the problem (e.g., the notion of the big bang may be said to have solved the conundrum of whether time has a beginning) or it retains its status as a genuine metaphysical problem-for the present. 

In this paper I want to once more cast the familiar metaphysical bones associated with monism to see if some new pattern will emerge which might help us decide about the status of the mind-body problem i.e., whether it is a scientific problem or, if there is such a thing, a genuine metaphysical one. But before I actually cast the bones, I would like to put before you a conclusion that might be drawn, if, at the end of this investigation, it became evident that metaphysical questions cannot be answered by science. If this conclusion were accepted, then an interesting consequence would follow: when faced with a metaphysical problem, we would find ourselves like Buridan's ass, stuck between the two (or more) metaphysical alternatives, uncertain which one is true but unable, as Kant put it, "to feign indifference to such enquiries, the object of which can never be indifferent to our human nature" (1933, A x). Like Buridan's ass, If we are not to starve to death, so to speak, it seems we must adopt a provisional metaphysical hypothesis (regarding questions concerning God, freedom, and immortality) in order to live our lives in the human way. The "leap in the dark" that is involved in such an adoption is not perhaps the disadvantage that it might seem to be at first blush. The fundamental uncertainty which infects metaphysical beliefs (an uncertainty which will underlie whatever belief we provisionally adopt)-far from being a bad thing-is, I suggest, a vital ingredient of the human condition. I argue for this suggestion as follows: if we could achieve metaphysical certainty with regard to our status, we might not regard human life as possessing the same intrinsic interest it seems to possess as a consequence of our present uncertainty. 

Why we need to live in metaphysical uncertainty can be illustrated most easily with respect to the familiar issue of our moral freedom. Thus, if we are the paragon of animals, but animals for all that, then we have no moral status since the idea that we are free agents-in the special sense that morality requires-is ruled out by our animal status, viz., our status as simply parts of Nature governed by natural laws. On the other side of the issue the same constraint applies: if we were, in fact, God's creatures (i.e., if we all knew that this was a fact) then-though we would know that we were deliberately created as free agents, the fact that we are in this world to simply exercise our freedom would effectively take away that freedom: the knowledge of our metaphysical status would constrain our behaviour (in line with God's laws) as effectively as Nature's laws. 

It seems, then, that to actually know our metaphysical condition would be a disaster. To live in the human way we have to not know the answers to these questions even though we inevitably find ourselves inclining one way or the other. This metaphysical uncertainty principle is, I suggest, what underwrites the human condition and what gives human life its unique character. Now since we do not know which metaphysical alternative is true, and since, as Kant rightly said, these are questions with respect to which we cannot be indifferent (since our attitude towards the alternative we incline towards affects the way we live our lives and we have to live our lives), it follows that we have to choose (in a provisional way) which metaphysical position we are to believe. Such a choice amounts to a rare case in which it makes sense to talk about belief voluntarism. Our adoption of a belief is voluntary in the following sense: in cases where science fails us (in cases concerning e.g., God, freedom, and immortality), appeals to experience can never decide the issue for us collectively.-the way they can when, for example, the issue is the freezing temperature of water As a consequence, different people will have experiences that will (temporarily) tip the balance for them one way or the other but which will still leave room for doubt. Individuals will then decide what they personally believe on the basis of their experience, but the experiences that turn the scales for them personally, will not be completely convincing, either for them or-a fortiori-for others. 

As a result, they will have a sense of their belief being provisional and in that sense, voluntary. In the case of metaphysical issues we must, it seems, make up our minds about what we believe. Generally speaking, this uncertainty-manifested in the provisional character of our metaphysical beliefs (and the fact that, typically, we we swing back and forth between alternatives)-is regarded as a sign of sanity by human beings. 

Thus, true believers, on either side of a metaphysical debate, tend to be regarded as fanatical by those who recognize that the questions at issue cannot be settled by experience, since, ex hypothesis, if they could be settled on this basis, everyone would be in agreement. Now, these conclusions related to the metaphysical uncertainty principle, are conclusions which we can draw only if metaphysical problems are not susceptible to scientific enquiry and this is far from being a settled issue, particularly in the case of the mind-body problem .(I am assuming here (with Kant) that all metaphysical questions are linked, so that a naturalistic answer to a particular question will imply a naturalistic answer to all the others and vice versa for 'supernatural' answers). 

Whether the mind-body problem is a scientific problem or an irreducibly metaphysical one One way to show that a particular question is not a scientific one would be to show that in confronting the problem we do not know how to propose testable hypotheses. In the case of the mind-body problem, this difficulty stems from a difference in the logic which governs the the way we talk of mental things (mentalese) and the way we talk of physical things (physicalese). To illustrate: it would be difficult to imagine how we could test the hypothesis that a neural network made of silicon had become conscious. We could certainly describe in physicalese, some test that would involve measuring physical parameters, voltages, etc., but this test, by definition, could not detect the presence of a mental state unless the mental state were to be defined in physical terms. And this is the problem: how do we define the one state in terms of the other without just stipulating the identity of the two states? In what follows, I will keep returning to this consideration (the question of integrating mentalese and physicalese) as a mean of keeping track of the discussion. 

Introduction to the casting of the bones

 During the last hundred years or so, since Darwin if you like, the conviction that the relationship between mind and body is a natural one-something open to scientific inquiry-has steadily gained ground. As a consequence, it is, at present, de rigeur, to believe in physicalism-a brand of monism which contends that nothing but the natural world exists and that human beings are a part of it, having evolved to our present state over millions of years. Since, it seems that this evolution to our present state must have happened-the alternative involves a magical conception of the universe-then there ought to be a natural way of understanding the relationship between mind and body This commitment to naturalism has-according to Owen Flanagan-the implication that there is a quick solution to the mind-body problem: neural states explain conscious states in that they are correlated with them: thus; he says . ..facts about the brain and facts about consciousness are on the table to be explained. We then infer that the constellation of a certain set of autophenomenological reports of restricted range ("tastes sweet") correlate with certain sorts of brain activity (activation in the relevant pathways), and we infer, because of an overall commitment to naturalism, that the latter explains the former (1991, 338). This raises the question of whether, if you are a naturalist there can be- ultimately-anything more to explanation than correlation. To be in a position to make a judgment about the legitimacy of this central assumption (that explanation need amount to no more than correlation) 

I need first to set the scene and to do so it will be necessary to put the physicalist approach in its metaphysical context. In the course of this review, I will-as I mentioned a moment ago-keep in the forefront the incompatibility between the logic of the two languages of mind and body as a (potentially) useful means of judging whether the mind-body problem is susceptible to scientific inquiry. I will also consider the explanation = correlation problem as it crops up in various contexts. 

Review of the metaphysical characterization of the mind-body problem 

The mind-body problem is a problem because of the difficulty we have in understanding the nature of the interaction between minds and bodies. This difficulty stems from the fact that minds and bodies seem to be such different sorts of things but, at the same time, seem to be constantly interacting. Dualism, as a metaphysical position, simply accepts that there is no way to explain this interaction. The scientifically repugnant aspect of Dualism is its declaration that there is no natural way of understanding how minds could interact with bodies but that, nevertheless, they do interact. Dissatisfaction with Dualism leads to monism via the following considerations. Dualists say that there is no natural way of explaining how mind-body interactions could occur. Their presumption is that natural explanations are available only when the interactions which interest us are between things of the same ontological type. Thus we feel we understand why one billiard ball moved when it was struck by another billiard ball because: a) they are both extended physical objects (the same ontological type) and; b) can therefore come in contact with each other (in a space common to both objects) and thus interact. Note that in the parallel case of mental interaction, we feel-though somewhat less confidently-that the interaction between two mental activities or states can be understood along somewhat similar lines. However, in this case, the imputed 'mechanisms' that explain how thoughts interact are psychological in character and rather vague.

 For example, laws of association sometimes hold and sometimes they do not. Thus, whenever I think of Hiroshima, I think of 'mon amour' or at least I did that time. Such laws of association are very general and come to little more that 'one thought often leads to another depending on preceding experience'. There are all sorts of other psychological features of cognition, but though these are of great interest the possibility of interactions between mental states does not loom as a metaphysical problem in any psychological account of the mind's operations. Therefore, since type-type interactions seem unproblematic, if we want to solve the mind-body problem-the problem of interaction-we need to argue for the right to redescribe minds and/or bodies so that they will be regarded as of the same ontological type. 


 Any such redescription leads to what can be characterized metaphysically as a type of monism. The great virtue of any monism is that-under such a redescription-interactions between minds and bodies appropriately redescribed, will be between entities of the same type and can thus be seen as natural, not magical. There are four types of monism: 1) Materialism or Physicalism, in which minds are in some fashion reduced to bodies; 2) Idealism, in which bodies are in some fashion reduced to minds; 3) Panpsychism, in which that which exists is regarded as having both physical and mental properties; and 4) Neutral Monism, in which the intellect attributes mental and physical properties to something which, in itself, cannot be characterized in either mental or physical terms. 

Each of these monisms suffers from the same type of problem, a problem which stems from the very redescription of minds and bodies which initially gives rise to these different monist positions. The problem is that our original descriptions of minds and bodies have evolved from our experience of what are-in terms of our experience of them-two very different sorts of things. Naturally, the logic of the descriptions we use to make reference to our experience reflects the differences we experience. 

For example, a particular billiard ball or neuron can have a temperature but a pain or a colour cannot. We have, then, two different languages governed by logics which reflect apparent ontological differences in the objects to which we make reference within each discourse. So a principal problem which confronts any version of monism is this: in order to speak of minds and bodies as if they were of the same type (and thus be in a position to solve the mind-body problem) we have to, in some plausible fashion, integrate the two extant languages. In the case of materialism we can integrate the two ways of speaking by regarding all references to mental experiences as nothing but a facon de parler: thus I may talk about my pain but there is no such thing. I am really referring to a c-fibre firing. What I do here is to discount the ontological status of the referents of mentalese. 

However, to make this discounting plausible, I really need to eliminate my experience of these referents. This is not as simple as changing one's linguistic habits. At this stage, materialism seems to require of its adherents an almost heroic capacity to, so to speak, live the implications involved in giving up folk-psychological talk. Dennett's reference to Zombies and the special sense in which consciousness is an illusion is-from the materialist standpoint-intellectually admirable-for Zombiehood is the human state in which the physicalist solution to the mind-body problem is properly realized without any embarrassing phenomenological leftovers. Dennett, for one, does not shrink from characterizing what must be accepted if one is to bite the metaphysical bullet that physical monism presents: the effective blanking out and or discounting of consciousness that will come to pass once one fully realizes that the puzzling features of consciousness (the Cartesian theatre, the sense of our registering the meaning of our experience, the sense of ourselves as the witness of all that passes, the qualitative feel of our experience, etc.,) are an illusion. 

Once it is realized that we only seem to be subjects of consciousness aware of a seamless web of experiences, these experiences will in some way lose their awesome sui generis status. The amazing thing about this view is that, if it is true, we are already in this monistic state metaphysically, we just do not realize ii: it seems to us that we are conscious, but-when we learn to regard the phenomena that make up consciousness as not entitled to any ontological pretensions, a mere illusion-this transparency of consciousness to itself will transforms itself into a what? a blankness? the zombie state? Talk about the power of positive thinking. 

Strawson explains the difficulty of articulating this characterization of consciousness as an illusion in the following passage: It has been suggested that experience might not really be a matter of qualitative character or phenomenology at all, that it might somehow be wholly the product of some cognitive faculty, the "judgment module" or "semantic intent module," and that we might to that extent be entirely deluded about its nature. Thinking along such lines Dennett has suggested that "there is no such thing [as] . . phenomenology." "There seems to be phenomenology," he concedes, "but it does not follow from this undeniable, universally attested fact that there really is phenomenology"( [1991. Consciousness Explained. Boston: Little Brown and Co., p 365-366;]. . .) 

It is very unclear what Dennett means by 'phenomenology', but this move fails immediately if it is taken as an objection to the present claim that we can be certain both that there is experience and that we cannot be radically in error about its nature. It fails for the simple reason already given: for there to seem to be rich phenomenology or experience just is for there to be such phenomenology or experience (1994, 52). b) 


 In the case of Idealism the integration problem is resolved by simply eliminating the category of matter. There is no need to integrate the vocabularies of the mental and physical language games since both mental and physical objects are nothing but objects of representation. According to Idealism, when we talk of physical objects in a metaphysical way, i.e., as existing independently of minds and having things like temperatures (whether anyone is experiencing them or not) of their having locations in space and time (independently of minds) this metaphysical talk is simply a facon de parler. In fact, nothing exists apart from perceivers and their experiences. 

On this assumption there cannot be a problem with reference to how ideas are related to brains or minds to bodies. Idealists freely admit that there are two different sorts of objects of representation (some displaying physical properties (brains, human bodies) some mental properties (hopes, pains), but objects of representation (whether displaying mental or physical properties) do not interact at all. They are inert and passive in character just as Berkeley insisted. Thus the idealist has no problem dealing with the problem represented by the fact that when, following Wilder Penfield, I stimulate a brain with a micro- electrode, this process seems to cause objects of representation to manifest themselves to the conscious subject. 

For the Idealist, this only appears to be a problem because the scenario suggested begs the question: all such apparent interactions between the mental and the physical 'things' are illusions: we only experience objects of representation and correlations between such representations are not interactions between them: they simply follow each other regularly or not, just as experience reveals. This correlation (or lack of it) can be accepted as a simple brute fact a la Hume or 'explained' metaphysically through God via occasionalism; or the preestablished harmony; etc., according to one's taste in such matters. The problem for Idealism is once again the problem of trying to eliminate something which is part and parcel -if I may put it this way- of our experience of experience. One of the features of experience that we experience over time is the constancy and coherence of certain aspects of it: e.g., the sun rising every day, etc. Our experience of the constancy and coherence of this kind of object of representation produces an irresistible urge to believe that they continue to exist when not in mind (so to speak) and it is this sort of extra-mental (independent) existence that is thought to be enjoyed by physical objects. Thus the constancy and coherence of a certain class of objects of representation is a factor that Idealism cannot explain without resort to either incredibly austere Humean assumptions or metaphysically extravagant Berkleian or Leibnizian theological hypotheses. The explanation of the constancy and cohrence of a certain class of object of representation through their causal relation with ontologically independent physical objects seems, by comparison, a wonderfully sensible (i.e., believable) hypothesis. 

Digression: how explanations reduce to correlations among monists

It is worth noting that, where a monistic metaphysic is used to solve the problem of causal relations between physical and mental entities, these relations become correlations, whether the monism in question is idealism or materialism. In the case of Idealism, they become correlations between the same types of entity, viz., objects of representation: thus any regular conjunction of such objects of representation, do not stand in need of any (causal) explanation with regard to the constancy of the conjunction observed. In effect, the idealist would be happy to follow Hume and not look for any causal explanation for such constancy that goes beyond the observed facts of experience: explanations are not required where the facts in question are simply brute correlations, not causal connections. 

In the case of materialism, the correlations are between physical entities which have been mistakenly classified as being of different ontological types. Thus, it seems to me that a sensation is a mental event, but since it is really a physical event then, once I allow this idea to sink in, mental events will no longer seem to me to be mental in character, i.e. denizens of a distinct ontological realm. Instead, they will accepted as physical events conjoined in our experience with other physical events. Constant conjunctions (such as those revealed in the Penfield experiment) will come to be regarded as no more than correlations revealed in the course of experience and, as such, in no need of any further explanation which would account for the constancy of the conjunction observed by appealing to some causal connection between the states. 

When materialism follows this path it can very easily slide towards panpsychism. This is because, if a physical event can come to seem like a mental event (when, by assumption, only physical events are included in our ontology) it must do so in virtue of the fact that mental qualities, feelings etc., are, in fact, aspects of physical events. Here arises the tendency of materialists to insist that consciousness is as much a part of the physical as electric charge, a view which is, effectively, that of panpsychism. However, among the hard-nosed materialists to whom panpsychism sounds like a fairy tale, we witness the eliminative option. According to the zombie version we only seem to have experiences of mental events; we only seem to be conscious and after a while-once the truth of the materialist hypothesis is fully absorbed-we will cease to be impressed by the ontological pretensions of these seemings, thus solving any correlation problems a fortiori . End of digression


In this case, the linguistic integration works both ways. Panpsychism hypothesizes that physical things are also mental insofar as their intrinsic ontological status is concerned. Panpsychism supposes that sensation is as natural to a physical thing as electric charge or mass. The integration which takes place need not, therefore, be linguistic: since physical phenomena have mental characteristics as well as physical ones it should not sound odd to say "that c fibre firing is in pain". In this way the mental characteristics of humans and animals can be seen to be stem naturally from the intrinsic nature of panpsychical substance. And the explanation can work both ways-an unexpected bonus. Not only do I understand how brains can have mental properties (because electrons, protons, etc., are the sorts of things that can feel) so too, I understand (on the model of my own behaviour) why physical things are moved to act in the way that they do (it is due to their psychology). 

Given this hypothesis, the linguistic integration follows straightforwardly: "electrons are attracted to positively charged surfaces" means just that attracted, i.e., they want to come into contact with such surfaces. etc. But the big payoff still lies in the fact that I do not have to explain how the physical can cause the mental: if the physical is mental then there is no problem about it having mental characteristics. The main objection to Panpsychism ( apart fromits the obvious silliness of imagan bricks to be unhappy) is that it amounts to property dualism. this is why it presents us with a metaphysical scandal and seems such a wild hypothesis. 

Thus Descartes was careful to identify his two substances with their leading properties. Here he followed the tradition that a substance was to be conceived in and through itself, i.e., in terms of its leading property. If a substance had two leading properties, it could not be a substance but instead had to fall into the catch-all category of a tertium quid, a third sort of thing-not simply extended, or thinking-but both. Descartes was driven to this notion of a substantial union when in the Sixth Meditation he recognized that (in terms of certain experiences that we have of pain and pleasure, for example) that minds and bodies were in some fashion intermingled. 

But since he was unable to explain this metaphysical interfusion of two properties (extension and thinking) in a single substance, he was forced to attribute the interfusion to God's hand, i.e., resort to magic. But magic is one thing and metaphysics is another and, to his credit, Descartes was never happy with the 'third thing' option. Where does this unhappiness stem from? It is interesting to find this same property-dualism being mooted in Strawson's and Nagel's' books ("consciousness is as much a physical characteristic as electric charge" (Nagel, 1986, 28; quoted approvingly by Strawson, 1994, 105) along with the suggestion that to solve the mind-body problem we need to change our concept of the physical in some unspecified way. (In the light of such considerations Strawson describes himself as an agnostic materialist.) 

We must make this change in order to be able to integrate consciousness with electric charge as both being aspects of the physical and, in doing so, not blush too deeply-as we have traditionally done when offered the option of panpsychism. The blush with panpsychism comes from the fact that we feel the problem wants solving via a reduction of the mental to the physical; a reduction that will explain mental phenomena the way that molecular chemistry explains more or less mechanically (i.e., via microstructures) why, for example, various elements can appear in both a liquid and a solid form. 

Such a microstructure solution would be in line with the favoured explanation schema of science. However to simply announce that physical entities can explain mental phenomena because they have mental properties does not amount to a 'proper' explanation. Thus in the case of panpsychism, a metaphysical mystery-mind-body interaction-has been replaced by a metaphysical fact that integrates minds and bodies by decree. One wonders what all the fuss was about in the first place if that is all that is required to set Jack free. 

Hence the blush: Nagel characterizes the blush nicely with his remark that the dual aspect theory can lead to panpsychism and, as he puts it: "Though it has its attractions as a way of unifying the radically disparate elements that give rise to the mind-body problem, it also has the faintly sickening odour of something put together in the metaphysical laboratory (1986, p.49). The problem with Panpsychism is that such an integration cannot be done on the cheap by metaphysical fiat. Especially, since, as Nagel points out, "We cannot at present understand how a mental event could be composed of myriad smaller proto-mental events on the model of our understanding of how a muscle movement is composed of myriad physico-chemical events at the molecular level. We lack the concept of a mental part-whole relation (1986, p. 50). 

However, one natural answer as to how an object could have a mental property and a physical property would be to consider the question from an epistemological point of view: we could simply attribute these properties to an object from the point of view of intellect and this ploy leads us to the fourth kind of monism. 

Neutral monism 

Here I 'integrate' mental and physical properties in one substance not by decree, but by pointing out that the attribution of ontologically different characteristics to the same thing is simply a mistaken projection (technically an 'hypostasization': the making into or regarding of something as a self- existent substance) of the epistemological fact that what exists can manifest itself to the intellect in two different ways. 

Thus the seeing eye and the physical eye are one and the same thing, but the one and the same thing which they are is not a physical or a mental thing. We cannot characterize it as it is in itself (i.e., as a substance) except to say that it manifests itself to us (to the intellect) under both a physical and a mental aspect. The differences between the physical and mental languages games just reflect this epistemological fact that some things can be experienced under two different aspects. 

On this construal of the situation there is no mind-body problem because minds and bodies do not interact. They are in origin-before we mistakenly hypostasize them-just different intellectual perspectives on something which is ontologically neutral (as between the physical and the mental). Does neutral monism as a solution, have an ad hoc air as did panpsychism? 

Philosophically, it is much more respectable since it does not involve positing a new kind of 'double essence' metaphysical substance, a tertium quid. It is also promising, in that interactions between modes of different 'substances' (c- fibres and sensations) are not puzzling when they are seen-as they should be- simply as correlations between modes of attributes. Thus, when the electrode touches my cortex-a mode of the attribute 'extension'-this is correlated with a certain memory-a mode of the attribute 'thought'. On this view the fact that intellect can experience substance under two attributes and that modes of these attributes exhibit correlations, allows us to understand the interaction of minds and bodies as a non-event since the 'interaction' is simply an illusion caused by hypostasizing (modes of) attributes, thereby imagining them to be interacting modes of different substances. 

The drawbacks associated with neutral monism lie in the fact that when we consider some of the implications of this view. First of all: how are intellects or points of view related to individuals? Some sense of this problem can be gauged by the phrase which Flanagan uses to describe the point of view of intellect. He says: The alleged mystery of consciousness has its source in biological facts that underwrite the different kinds of epistemic access we have to brain facts, on the one hand, and what it is like to be each one of us, on the other. We grasp facts about the brain through our sensory organs, . . . we are acquainted with consciousness by way of [and here is the phrase to note:] 'direct, internal, reflexive biological hookups to our nervous systems' (1991, p. 343). Granted we are 'hooked up', but surely it is the nature of this 'hook up' that is so mysterious. The clarifying phrase "direct, internal, reflexive biological [hookup] . . ." in this context seems to me to be about as helpful (vis a vis understanding what is involved metaphysically in the notion of an epistemic viewpoint, an intellect) as the notion of animal spirits circling the pineal gland in Descartes' explanation of the mind's relationship to its brain's activities. (This is a point that I will have more to say about below under the heading ' Frege's Thesis'.) 

Secondly, neutral monism raises the question of whether all individual substances have intellects. Do then stones have thoughts and what are we to make of that? Spinoza just bites this bullet, but others might not be quite so happy to do so since, as Nagel remarks (see above), neutral monism tends to collapse into a kind of panpsychism by attributing intellects to all individuals made of the neutral monist stuff. A nice example of this predicted collapse arises in a recent paper by D. J. Chalmers: . . . of course the double aspect theory is extremely speculative and is also underdetermined, leaving a number of key questions unanswered. 

An obvious question is whether 'all' information' has a phenomenal aspect. [Here information is the name given to the neutral substance of the world following Wheeler's suggestion that information is fundamental to the physics of the universe, (1990).] 

One possibility is that we need a further constraint on the fundamental theory, indicating just what 'sort' of information has a phenomenal aspect. The other possibility is that there is no such constraint [here panpsychism is allowed in] . . . A mouse has a simpler information processing structure than a human and has correspondingly simpler experience, perhaps a thermostat, a maximally simple information processing structure, might have a maximally simply experience" (1996). 

Concluding summary on the monist solutions to the integration problem 

In a nutshell: a) idealism involves no linguistic integration since there is no interaction between physical and mental objects of representation thanks to their passive inert status. Instead their apparent interaction is a mere correlation and this fact about the correlation of physical and mental objects of representation thus calls for no explanation since the objects of representation concerned never actually interact. b) In the case of Physicalism the hope is that no linguistic integration will be needed since none will be required once experience is either eliminated or ignored as a causally irrelevant epiphenomenon. c) Panpsychism involves property dualism by decree and there can be no integration by decree. Symptom: it just sounds silly-that is, empty of explanatory power-to say electrons feel a desire to unite with other particles of the opposite charge and that is why they do it. d) Neutral monism successfully integrates the two ways of speaking by assuming a strange fact: viz., that one and the same thing can be experienced from two fundamentally different perspectives. e.g., a first person perspective (the seeing eye) and a third person perspective (the physical eye). Nothing can mitigate this strangeness, viz., that one thing should be capable of manifesting itself in two such different ways to something called an "intellect". If we cannot accept this fact as fundamental and wish to integrate these two perspectives (perhaps via the notion of panpsychism) such a move simply attempts to revive the idea that it makes sense to talk of what sort of thing the noumenon (the neutral metaphysical substance) is. Spinoza does this in an agnostic way (but indicates that talk about it will not be informative: (see Ethics I, xvii, Note) and in modern times, Nagel, as we have seen, notes the arbitrary character of such metaphysical talk. 

The important outcome of this consideration of the integration problem is that, in this last case, a feature of the metaphysical situation emerges which is present in all four cases and needs to be recognized. This is what Strawson characterizes as Frege's thesis This thesis is simply that, if there is such a thing as the point of view of intellect-the notion of an experiencer as opposed to an experience-then what ontological category is it, the experiencer, going to go into? (It needs to be, in Strawson's phrase, " [a] basic stuff suited to the task of realizing experience" 1994 ,124) This nonexperiential subject of experience is a conceptual necessity along the lines of this familiar argument: if a quality is to be like something it must be like something to something. We need an experiencer to serve as a subjective medium in which sensations, feelings and thoughts can be realized. 

But how are we to characterize this necessary element? It would seem that we have a serious problem if we do not identify this element with a 'soul' defined as a thing composed of "the basic stuff suited to the task of realizing experience". Thus, if we identify this basic stuff with a physical thing, a brain or a nervous system, the problem with this solution is the same as that associated with panpsychism. It simply constitutes a metaphysical 'quick fix'. To constitute a satisfactory answer, I must somehow be able to see how things like nervous systems could be realizers of experience. That they are, is pretty likely, given things like the Penfield experiment, and the basic commitment to naturalism. But how this 'realizing' relationship to be properly understood is what constitutes the hard problem in the philosophy of mind and it is this difficulty which accounts for the present stalemate in this area. 

In brief, the stalemate amounts to this: cognitive scientists are willing to settle for correlations between brain states and states of consciousnes whereas agnostic materialists insist on explanations in which we can see how brains states generate conscious states. (Mysterians are agnostic materialists who have given up hope. They are distinguished by the contention that we will never be able to grasp the connection even though it is a natural one.) The cognitive scientists, such as Flanagan, want to accept correlations as a sufficient basis for explanations; the agnostics want more. They are made up of, on the one hand, the Mysterians who say: it can't be done: consciousness is natural but it is inexplicable, and the true naturalists, e.g., Crick, Penrose, Strawson, Searle) who will never be content with anything but a proper explanation-something modelled on proper explanations elsewhere in science (microstructures, etc.). 

Strawson on correlation as explanation.

 In essence correlationists say: explanation comes to an end, and it comes to an end with correlations: 'Whenever events of type A occur, then events of type B occur'. . . this is just how things are'. . . . [Furthermore, such a corelation] is no more 'intrinsically intelligible' when it holds between two nonexperiential phenomena [billiard balls] than when it holds between an experiential phenomenon [a pain] and a nonexperiential phenomenon [like a "brain event]" (Strawson 1994, 85). Strawson's first objection to this stance is that, although there are plenty of strange correlations in, for example, physics, yet they are integrated with the rest of physics and this is what makes our theoretical understanding in this area satisfying. By contrast, the lack of integration of experiential phenomena with the rest of physics makes the correlations which we note unsatisfying. Thus brain injuries are correlated with phenomenological deficits, but our theoretical understanding of this correlation is entirely absent. But why should this matter? Strawson points out, e.g., that we do not really understand quantum theory, i.e., why light behaves as it does in the two slit experiment-all we have are correlations here, (brute facts) even though the theory is theoretically satisfactory-a powerful predictor, etc. (1994, 87-88). Strawson answers this objection by reference to the strong homogeneity (or theoretical integratedness) of the predicates used in physics and related sciences. "These predicates recognizably form part of the same family, the same overall system of description. 

The problem is that experiential predicates do not fit into this family or system of description and we have no idea, at present, of how they might be integrated. This is the problem of experience: all experiential phenomena are physical phenomena, but we cannot fit them into the account of the physical delivered by physics. We know that they are actual, but we do not understand how they are possible or why they occur as they do, given all that we know about the physical as described by physics. 

We do not understand why they occur as they do in the way that we feel we understand why many other physical phenomena occur as they do, given the account of the physical delivered by physics " (1994, 88) 


My conclusion from this survey of the various problems which beset the attempts to solve the mind-body problem is that the essential problem which confronts us when we try to treat the mind-body problem as a scientific problem-when we espouse naturalism-is the recalcitrant nature of the data. In essence, the problem is that the data concerning experience (and experiencers) do not fit in with the data about bodies as described by physics. However the theorist twists and turns, it seems impossible to surmount this basic difficulty. 

This explains the difficulty of integrating the two languages which reflect these differences in data and the persistent tendency to eliminativism on the part of naturalists. It also explains the 'correlation = explanation' syndrome. Those who, in the face of this difficulty with the data, abandon a scientific approach are inevitably driven towards metaphysical solutions (as is evidenced by the quotation from Chalmers above where he dabbles in double aspect theory and a version of panpsychism). But these metaphysical hypotheses are not testable and do not yield any collective agreement. 

This leaves one in the position of having to weigh up the metaphysical options to see which seems the most plausible where the criteria relating to what makes an option plausible are not compelling. 

Now, from the point of view of plausibility, Dualism has, on its side, its frank acknowledgement of the problem of the recalcitrance of the data. Compared to the various monisms, it almost seems hard-nosed in its response to the mind-body problem since it accepts that the recalcitrant data must be acknowledged and given their proper weight. By comparison, consider what a scientific monist-an agnostic materialist-must believe in order to keep the faith with repect to finding a solution to the mind-body problem. Strawson lays out the credo clearly: Materialist must confess to both their ignorance and their faith." (1994 p.96) 

My faith, like that of many other materialists, consists in a bundle of connected and unverifiable beliefs. I believe that experience is not all there is to reality. I believe that there is a physical world that involves the existence of space and of space occupying entities that have non experiential properties. I believe that the theory of evolution is true, that once there was no experience like ours on the planet whether panpsychism is true or false, and that there came to be experiences like ours as a result of processes that at no point involved anything not wholly physical or material in nature. 

Accordingly, I believe that however experiential properties are described there is no good reason to think that they are emergent, relative to physical properties, in such a way that they can correctly be said to be nonphysical properties. Finally, with (Nagel, l986 28) I believe that one could, in principle, create a normally experiencing human being out of a piano. All one would have to do would be to arrange a sufficient number of the piano's constituent electrons protons and neutrons in the way in which they are ordinarily arranged in a normal human being. 

Experience is as much a physical phenomenon as electric charge (1994 ,105). Evidently, from the point of view of what you must believe, it is not easy to be a practicing materialist, even a practicing agnostic materialist. But the point at issue is: is it any easier than being a dualist, i.e., adopting what is-from the monist perspective-a frankly magical solution to the problem? 

Consideration #1) The time-frame problem:. Materialists speak fondly of a perfected science, a notion which by comparison to the second coming can seem a very long way off. As Nagel puts it: An integrated theory of reality must account for this (the fact that bodies have minds) and I believe that if and when it arrives, probably not for centuries, it will alter our conception of the universe as radically as anything has to date (1986, 51). Such a remark about altered conceptions simply opens up the metaphysical horizons again and one wonders whether the conception of 'the physical' we arrive at in the distant future would have the requisite scientific appearance as this term is now understood.

 Consideration # 2) Could any advance in science solve a metaphysical problem? Any monist solutions must be in terms of a theoretical integration of the recalcitrant data. But what sort of theory could integrate such different things as as a felt sensation and a nerve firing? Strawson remarks: One might put the point [about the hardness of the mind-body problem] by saying that even if we could make a machine that had experience, and even if we could know (per impossibile) that we had done so, we still would not be able to give any explanation, in physics terms, of how it was possible that it had experience-so long as we were operating within the confines of our current physics-based conception of the physical (1994, 95). 

The point is not just that a Maxwell of the Mind might not someday arise, but rather the difficulty of actually believing this could happen in the light of our present characterization of the problem. Is it easier to believe that the mind-body problem will be solved one fine day or that the universe is actually a Cartesian one and that there is no way (save magic) to explain the interfusion of minds and bodies? Costa puts our present dilemma as follows: I conclude that, in spite of all the well-intended approaches to the problems of consciousness such as Churchland's here, the qualitative aspect of consciousness remains as puzzling as ever. Despite all the scientific-technological advances over the centuries, perhaps we have reached a point of being forced to simply acknowledge our ignorance without prospect of any quick improvement in that state. 

This is by no means accepting 'mysterianism' or supernatural concepts. On the contrary, it is only by precisely characterizing our lack of knowledge that solid basis for further scientific advances can be achieved. After all, there are worse things than not knowing the answers to our questions (1996). The position we are left with is the following: so far at least, it has been impossible to decide whether the mind-body problem is amenable to a scientific solution. Given that our science at present is very sophisticated-particularly our physics-there is ground for the presumption that the problem is, after all, a metaphysical problem, and that no physical (i.e scientific) explanation of consciousness will be forthcoming. 

From this follows The metaphysical uncertainty principle which I outlined at the beginning. Two short paragraphs to refresh your memory: 

Many metaphysical concerns present themselves as opposing alternatives: for example, either determinism is true or we have free will; either things can happen without a cause or they cannot; either we are simply animals on the third planet or we are embodied souls. What seems clear is that we often have to decide between these alternatives for various practical purposes (living our moral lives, for example), but that, at the same time, no one is able to show clearly-i.e., so as to induce agreement in anyone who listens to the argument- that one or the other alternative is true. 

This leads to the notion of belief voluntarism. Usually you cannot just decide what to believe: the evidence for a proposition builds up one way or the other and our beliefs are relevantly coerced. But metaphysical alternatives seem to constitute cases in which one can choose to believe one way or the other. 

Thus, where there is, apparently (given our track record), no way of settling a metaphysical disagreement, the effective upshot is that one is free to adopt whatever metaphysical position seems more congenial. Naturally, any such such beliefs will be tempered by uncertainty and this tempering is what allows us to live as human beings. 


D. J. Chalmers (l996) "Facing up to the problem of consciousness". Alta vista net site. and MIT Press (forthcoming). 

Owen Flanagan (1991), The Science of the Mind, 2nd edition, Boston: MIT Press. 

Nicholas Humphrey (1995), Soul Searching: human nature and supernatural belief, London: Chatto and Windus.

Immanuel Kant (17871961), Critique of Pure Reason, trans. Norman Kemp Smith, London: Macmillan. 

Thomas Nagel (1986),The View from Nowhere. New York: Oxford University Press. 

Galen Strawson (1994), Mental Reality, Cambridge, Mass., MIT Press. 

Luciano da Fontoura Costa (1996) 'Do seated souls experience slumberous sensations'. Review of The Engine of Reason by Paul Churchland to be found at Psyche on the Internet. Cybernetic Vision Research Group IFSC - University of Sao Paulo 

Wheeler, J.A. 1990. 'Information, physics, quantum: The search for links' in (W. Zurek, ed.) Complexity, Entropy, and the Physics of Information, New York: Addison-Wesley.