IS THE MIND-BODY GAP SEMANTIC OR EPISTEMOLOGICAL?
In recent years there has been a growing body of literature devoted to explaining precisely why the mind-body problem has appeared so intractable. In the light of the perceived failure to carry out a successful reduction of the mental to the physical, a number of philosophers have set out to explain what it is that makes statements about mind-body identity more problematic than scientific identity statements such as water = H2O or lightning = electromagnetic discharge. Some, like Jacksonand Kripke,have appealed to Cartesian-style arguments that invoke conceivability as a guide to possibility in order to demonstrate that the identity of mind and body is metaphysically contingent. Others, such as Nagel, Levineand McGinn, by contrast, have argued only in favour of epistemic non-identity. In particular, Levine has warned against drawing metaphysical conclusions from epistemological premises and unambiguously condemned Jackson’s and Kripke’s metaphysical attack on physicalism by exposing and rejecting the rationalist assumptions on which their argument is based.
Whilst rejecting Jackson’s and Kripke’s modal rationalism, Nagel, Levine and McGinn nonetheless concede that physicalism is unable to account for the qualitative character of experience, and that, whereas there may be no real distinction between the mind and the body, there certainly is an epistemological one since we access our mental states in a very different way from that in which we access our physical states. In other words, even if physicalism were the whole story metaphysically speaking, it cannot be the whole story epistemologically speaking because introspection yields a technicolor phenomenology that is unaccountable from within the objective perspective. Thus whereas for Kripke and Jackson the gap in question is ontological, for Nagel, Levine and McGinn it is essentially epistemological.
In this paper I explore an alternative to the metaphysical challenge to physicalism posed by Jackson and Kripke and to the epistemological one exemplified by the positions of Nagel, Levine and McGinn. On this alternative the gap is neither ontological nor epistemological, but semantic. I will refer to the Kripke/ Jackson challenge to physicalism as the ontological thesis, to the Nagel/Levine/McGinn challenge as the epistemological thesis, and to my own alternative as the semantic thesis. Like the proponents of the epistemic thesis, I do not endorse modal rationalism since I share their scepticism concerning the rationalist metaphysics that leads Kripke and Jackson to mount a metaphysical challenge to physicalism. But unlike the proponents of the epistemological thesis, I argue that what makes the mind-body problem into a philosophical problem is not the fact that we access mental and physical phenomena in very different ways, but the fact that we mean very different things when we speak about the mind and when we speak about the body. I claim that it is because the gap is semantic in nature that the mind body-problem is a quintessentially philosophical problem that is not likely to simply wither away as our natural scientific knowledge advances.
On the semantic thesis the philosophical problem of the relation between mind and body is firmly connected to a conception of philosophy as a disambiguating activity that enables us to discern different senses even where there is only one referent. A supporter of the semantic thesis is therefore primarily committed to the ineliminability of the analytic/synthetic distinction, rather than to the ineliminability of two modes of epistemic access: introspection of the inner world and inspection of the outer one. For this very reason it is not possible to accommodate a dual aspect theory that construes the gap in semantic (rather than epistemological) terms within a naturalistic framework, since the semantic thesis that is defended here is closely connected with a conception of philosophy as first science. In this respect the semantic thesis differs drastically from the epistemological thesis.
Most supporters of the epistemological thesis are physicalists who detect an epistemological lacuna in the method of natural science. Nagel, for instance, claims not that physicalism is false, but that ‘we do not have the beginnings of a conception of how it might be true’.Similarly, for Levine, it is the capacity of physicalism to explain the phenomenal character of experience that is at stake, not its truth. The epistemological thesis is therefore not intended as a challenge to physicalism in the way in which the metaphysical thesis clearly is. For Nagel and Levine, physicalism is actually true, but it just leaves certain aspects of our experience unexplained. This incipient naturalism is clearly revealed in McGinn’s work, where the epistemological thesis first developed by Nagel and Levine provides the basis for a deflationary approach to the philosophical problem of mind-body dualism.McGinn, like Nagel and Levine, begins by noting that there is something that the objective perspective leaves out, namely the qualitative element, that answers to the question ‘what is it like to be an X?’. For McGinn the problem of mind-body dualism arises
because we are cut off by our very cognitive constitution from achieving a conception of that natural property of the brain (or of consciousness) that accounts for the psycho-physical link. This is a kind of causal nexus that we are precluded from ever understanding, given the way we have to form our concepts and develop our theories. No wonder we find the problem so
McGinn then adds that the fact that we are cognitively closed with respect to the natural property that accounts for the psychophysical link entails ‘there is no philosophical (as opposed to scientific) mind-body problem’.
The semantic thesis developed here effectively undermines McGinn’s deflationary approach to the problem of mind-body dualism. I intend to show, first, that the mind-body problem is a philosophical problem, and second, that the problem persists not because of some kind of cognitive inability on the part of human beings to grasp the psycho-physical relation, but because of the peculiar, i.e., purely semantic, nature of the mind-body distinction. To clarify the point: my claim is not that there is no epistemological gap as such, but that it is the existence of a semantic gap that makes the mind-body problem into a recurrent philosophical problem. Thus, whereas reformulating the mind-body gap in semantic terms does not entail denying that there is a distinctive phenomenology that is inadequately accounted for from an objective perspective, it does entail shifting the focus away from a consideration of the qualitative character of experience to a reflection on the meanings of assertions which employ the concepts of mind and body.
The argument that I advance here is a reconstruction of the account of philosophical analysis that Collingwood developed in An Essay on Philosophical Method (EPM) a book that contains what is arguably the most powerful explanation in the twentieth century of why philosophy has a distinctive subject matter that differs from that of the sciences of nature. My goal is to elaborate on Collingwood’s account of the role and character of philosophical analysis to explain why the mind-body problem persists. I should make it clear at the outset that it is not the purpose of this paper to defend an exegetical thesis. I can easily envisage a number of prima facie reasons why readers with more than a passing acquaintance with Collingwood’s work may doubt whether some of the claims discussed here are Collingwood’s own. For the purpose of this paper I am happy to concede that I have taken up one of Collingwood’s ideas and freely developed it in my own way. In the following I explain, first, why philosophical problems are semantic in nature, and second, I explore the implication of this claim for the mind-body problem.
In order to discover what constitutes a peculiarly philosophical problem we must begin from the fact of philosophical practice. And when we do consider the practice of philosophy we find that there are indeed problems that recur again and again, problems such as that concerning the compatibility of free will and determinism or the criteria for personal identity. In An Essay on Philosophical Method Collingwood provided an ingenious explanation as to why these problems exist and subsist. We can get a grip on why philosophical problems exist at all only if we are willing to concede that there are non-empirical concepts and that there are non-empirical distinctions.
What is an empirical classification and what are its features? Collingwood claimed that the coordinate species of an empirical genus form mutually exclusive classes. Take for instance the empirical genus “colour” and its coordinate species “red” and “blue”. The objects which fall under the concept “red” cannot fall under its coordinate species “blue” since no object can be both red and blue at the same time. Take, as another example, the empirical genus “mammal” and its coordinate species “cow” and “goat”. The objects which fall under the concept “cow” cannot fall under that of “goat”. The coordinate species of this genus, therefore, form mutually exclusive classes. In other words, the coordinate species of an empirical genus cannot be extensionally equivalent. Philosophical distinctions differ from empirical classifications in that they allow for extensional overlap: the coordinate species of a philosophical genus form mutually overlapping classes. Let us consider three examples of philosophical distinctions, one which belongs to moral philosophy, one which belongs to aesthetics and one which belongs to the philosophy of mind. Moral philosophers are used to distinguishing between actions which are performed from the motive of duty and actions which are performed from prudential considerations. But the philosophical distinction between the principle of duty and that of utility is not an empirical classification since some actions which exemplify the motive of duty could also be carried out on the basis of consequentialist considerations. In Kant’s Groundwork, for body problem, see also ‘Collingwood’s “Solution” to the Problem of Mind-Body Dualism’, Philosophia 32 (2005), pp. 349–368 and ‘Idealism and the Philosophy of Mind’, Inquiry 48 (2005), pp. 395–412. example, the action of the shopkeeper who returns the correct change in order to retain his custom is performed on the basis of prudential considerations, but it outwardly conforms to the demands of morality and could equally be used to illustrate the principle of duty. The principle of duty and that of utility, therefore, allow for extensional overlap, although such overlap is ruled out in the case of empirical classifications. Another example of a philosophical distinction is that between kinds of art such as music and poetry. Whereas empirical classes cannot overlap, music and poetry can be jointly instantiated in, say, a Bob Dylan song. Whilst a thing cannot be both red and blue, a cow and a goat, it can be both music and poetry at the same time. Analogous considerations are relevant to the kind of distinctions at work in the philosophy of mind, such as the distinction between persons and bodies. The distinction between persons and bodies is not advanced as an empirical classification that subdivides existing entities into non-overlapping classes in the way in which the subdivision of higher primates into chimpanzees and humans is intended to do. The distinction between persons and bodies is a semantic distinction and as such allows for extensional overlap. The task of philosophy, as Collingwood puts it, is ‘the distinguishing of concepts . . . coexisting in their instances’.It is in this way that philosophers distinguish between the principles of duty and of utility, between aesthetic genres such as music and poetry, and between persons and mere bodies even when there are no empirical classifications corresponding to such distinctions. Let me now turn to consider two objections that might be raised against Collingwood’s account of how philosophical distinctions differ from empirical classifications.
It may be argued that overlap of classes is not a distinctive feature of philosophical concepts since empirical concepts too allow for extensional overlap. The concepts of “having a beak” and “having feathers” are empirical concepts. Yet they overlap in their instances, i.e., in birds. Empirical overlap of this kind is ubiquitous but such an objection may be quickly answered by pointing out that “having a beak” and “having feathers” are not coordinate species of the same empirical genus. They are rather like the concepts of “brown” and of “wool” which indeed coexist in this brown woollen jumper, but which are not supposed to capture an important juncture in nature in the way in which the classifications of vertebrates into mammalian and oviparous creatures and of mammals into cows and goats are intended to do. Further, whereas we can find partial overlap in empirical concepts, as in the case of “brown” and “wool”, or “animals with a beak” and “animals with feathers”, the coordinate species of philosophical concepts in principle allow for complete extensional overlap, since philosophical distinctions are purely intensional distinctions that one would want to make even where there are no extensional differences. Thus moral philosophers would want to distinguish between the principle of utility and that of duty even in a hypothetical scenario where virtue really promoted happiness and the duty/utility distinction made no difference to the action one has to perform. To elucidate what is meant by a purely intensional or semantic distinction we might take a moment to reflect on what happens when such distinctions are not drawn.
The implications of the failure to make the relevant semantic distinctions can be gleaned from considering some of the problems encountered by Aristotelian ethics. Aristotle, as is well known, did not clearly distinguish between virtue and happiness. The concept of eudaimonia, which covers both, is not a composite concept made up of heterogeneous elements; it is an homogeneous whole in which virtue and happiness have no independent conceptual existence. Thus, for Aristotle, the virtuous person also enjoys a prosperous life from a non-moral point of view, just as those who fail to distinguish between the concept of love and that of jealousy automatically assume the jealous man to be a man in love. To have the concept of eudaimonia requires not making, but failing to make the distinction between moral and non-moral kinds of goodness. In order to operate with the concept of eudaimonia we have to make not more, but fewer conceptual distinctions. The Kantian critique of Aristotle’s moral philosophy amounted precisely to introducing a distinction that Aristotle did not make between categorical and hypothetical imperatives in order that we could consistently entertain the thought that virtue may go unrewarded. Kant certainly did not intend the distinction between actions undertaken out of the principle of duty and those undertaken for instrumental reasons to be an empirical classification. As we saw, the concept of duty and that of utility may overlap in their instances, as in the case of the action of the shopkeeper. But it is only because the distinction is made at all that it is also possible to think, contra Aristotle, that virtue may not be advantageous in an empirical sense. Progress in philosophical enquiry often occurs through the introduction of semantic distinctions which resolve problems created by their absence. The introduction of semantic distinctions, such as the one between the principle of duty and that of utility, is a very different matter from the discovery of another species of human, such as Homo floresienses, the hobbit-like creature found to live on an island east of Bali between Asia and Australia. The introduction of a philosophical distinction does not entail the addition of an empirical class that was previously unknown, but a refinement of our understanding of what it means to be good and in what different senses an act can be said to be good. Philosophical distinctions enable us to identify a thing as a particular kind of thing, as say, a morally worthy action as distinct from a prudential action or a rational as distinct from a non-rational being. But the kinds singled out by the coordinate species of a philosophical genus may correspond to no empirical kinds since philosophical distinctions do not ‘cut nature at the joints’, but bring out what we mean when we speak of a moral rather than an immoral action, of a person rather than a mere body etc.
Let us now consider a second objection to the doctrine of the overlap of classes. A more powerful counter-example to the claim that the coordinate species of philosophical concepts, unlike those of an empirical genus, allow for extensional overlap, however, might seem to lie in the existence of hybrids such as Tyrannosaurus Rex. For some time a dispute has raged amongst palaeontologists which were divided as to whether T Rex was a predator or a scavenger. The dispute was fierce because it was assumed that being a predator or being a scavenger were coordinate species of the same empirical genus and that they therefore captured an important juncture in the natural world. The dispute however was ultimately settled by claiming that T Rex was both a predator and a scavenger, thereby suggesting that overlap of classes is not a distinctive feature of philosophical concepts. But even the surprising way in which this dispute was ultimately resolved does not cast serious doubt on the claim that philosophical distinctions differ in kind from empirical classifications because the doctrine of the overlap of classes entails that there strictly speaking are no ‘examples’ of philosophical concepts. The action of the shopkeeper illustrates what it means to act on prudential considerations; it is not an example of a prudential action in the way in which Dolly is a specimen of a sheep. Since there are strictly speaking no examples of philosophical concepts, the particulars in which the coordinate species of a philosophical genus coincide are not hybrids: philosophical concepts simply are not jointly instantiated in the way in which empirical concepts are. Thus, if we say of human beings that they jointly instantiate the concepts of body and mind, we do not mean that the human being is partly body and partly mind in the way in which a centaur is partly horse and partly human. As Collingwood puts it:
. . . man’s body and man’s mind are not two different things, but the same thing . . . as known in two different ways. Not a part of man, but the whole of man is body in so far as he approaches the problem of self-knowledge by the methods of natural science. Not a part of man, but the whole of man is mind, in so far as he approaches the problem of self-knowledge by expanding and clarifying the data of reflection.
Since the objects which exemplify more than one philosophical concept are not hybrids, the overlap of classes does not pose the same problem for philosophical distinctions as it does for empirical classifications. When philosophers encounter concepts that coincide in their instances, they do not assume that the thing to do is to rearrange their conceptual scheme. The natural reaction of philosophers is to find ways of retaining semantic distinctions even when they make no empirical difference. This, for instance, is how Berkeley’s immaterialist turn sought to deal with the distinction between real and imaginary objects. What he claimed was not that we ought to forsake the distinction between real and imaginary objects, but that we should draw it in a different way, that what we call a distinction between real and imaginary objects is in fact a distinction between ideas which are more or less lively, more or less orderly and more or less coherent. When philosophers encounter distinctions that coincide in their instances, their natural reaction is not to abandon them, but to find a way of preserving and reformulating them.
So far we have considered three philosophical distinctions, one in moral philosophy, one in aesthetics and one in the philosophy of mind, and argued that philosophical distinctions are qualitatively different from empirical classifications because the former express purely semantic distinctions. Philosophical disputes address semantic questions (e.g., what does it mean to be a person rather than a body?) and opposing positions in philosophical debates (like duty-based ethics versus consequentialism in moral philosophy, causalism versus non-causalism in the philosophy of action) do not carve up reality along the lines of empirical kinds, but along the lines of distinctions of reason.
This conception of the nature of philosophical problems casts a very different light on to the mind-body problem. As we have seen, in contemporary discussions in the philosophy of mind the mind-body problem is regarded as a somewhat special issue that arises from the fact that mental and physical states are accessed in very different ways. The meta-philosophical views just discussed do not see the mind-body problem as a special kind of problem since they regard the mind-body distinction as similar to other purely intensional distinctions found in other branches of philosophy such as ethics and aesthetics. Thus, on this account of the origin of philosophical problems, the persistence of the mind-body problem is not due to the epistemological fact that mental states are accessed in very different ways from bodily states. The mindbody problem arises because the mind-body distinction is a semantic distinction rather than an empirical classification; it persists because there are claims that are true in virtue of meaning and as such they cannot be falsified in the light of emerging empirical evidence. There is a philosophical mind-body problem and it is here to stay, at least for those who are reluctant to relinquish the analytic/synthetic distinction.
The implications of the claim that the mind-body distinction is neither ontological nor epistemological, but semantic, are far reaching and spelling them out would necessarily go far beyond a discussion of the literature most closely associated with the debate concerning the explanatory gap. Two brief considerations, however, may be offered by way of conclusion.
First, denying that the mind-body distinction is epistemological in favour of the semantic thesis entails that knowledge of the psycho-physical relation is not so much beyond our cognitive grasp as irrelevant to our understanding of mind. It is irrelevant because the concept of mind is logically required in order to identify any given particular as mental. An investigation into the neurophysiological basis of consciousness involves the application of a causal explanation and thus of a category that is intrinsically unsuitable to describe the mental qua mental. If there is no scientific solution to the mind-body problem, this is not because we are unable to comprehend how type physicalism might be true, but because causal explanations of the emergence of consciousness, even if they could be found, are simply not explanations of mind.
Secondly, denying that the mind-body distinction is ontological in favour of the semantic thesis entails endorsing a particular view of the nature of metaphysical disputes. On this view, metaphysical disputes are not about what really exists but about the categorial structures we employ to identify what there is: metaphysics is ultimately a form of conceptual analysis. This view of the mindbody problem as an essentially semantic problem thus rests on an identification of the task of philosophical analysis with that of conceptual clarification that bears some similarities to the linguistic turn. Yet whilst the semantic thesis identifies metaphysical analysis with conceptual analysis, it does not endorse the view, often associated with Ryle and Wittgenstein, that philosophical problems are pseudo-problems which will wither away, not as a result of scientific advances, but of conceptual clarification.It is the very fact that we keep on making semantic distinctions, or distinctions to which there correspond no empirical differences, that explains why the mind-body problem has withstood the test of time and why there will always be a need for philosophical analysis. The semantic thesis is thus neither an attempt to solve the problem empirically (or to explain why the scientific solution, whilst in principle possible, is beyond our comprehension), nor is it a deflationist attempt to dissolve the problem a priori. It is an attempt to show why the problem is here to stay.
 I would like to thank my colleague James Tartaglia for a number of fruitful discussions on the explanatory gap.  Jackson, F., ‘What Mary Didn’t Know’, Journal of Philosophy 83 (1986), pp. 291–295; reprinted in The Nature of Consciousness, Block, E., Flanagan, O. and Guzeldere, G. (eds.), (Cambridge, Massachussetts and London, MIT Press), 1997, pp. 567–570.  Kripke, S., Naming and Necessity (Oxford: Blackwell), 1980.  Nagel, T., ‘What is it Like to be a Bat?’ in Mortal Questions (Cambridge: Cambridge University Press), 1979.  Levine, J., ‘Materialism and Qualia: The Explanatory Gap’, Pacific Philosophical Quarterly 64 (1983), pp. 354–361.  McGinn, C., ‘Can We Solve the Mind-Body Problem?’ in the Nature of Consciousness, Block, E., Flanagan, O. and Guzeldere, G. (eds.), (Cambridge, Massachussetts and London: MIT Press) 1997, pp. 529–542.  Nagel, T., ‘What it is Like to be a Bat’, p. 177.  More recently McGinn has articulated this position in Consciousness and its Objects (Oxford: Oxford Clarendon Press), 2004.  McGinn, C., ‘Can We Solve the Mind-Body Problem?’ in The Nature of Consciousness, p. 529.  Ibid, p. 531  Collingwood, R. G., An Essay on Philosophical Method (Oxford: Clarendon Press), 1933.  For a fuller account of EPM see my Collingwood and the Metaphysics of Experience, (London and New York: Routledge), 2002. For Collingwood’s engagement with the mind-  R. G. Collingwood, An Essay on Philosophical Method, p. 51.  R. G. Collingwood, The New Leviathan (Oxford: Clarendon, 1942, revised edn. 1992), p. 14.  On this see ‘Collingwood and Ryle on the Concept of Mind’, Philosophical Explorations VI (I), 2003, pp. 18–30 and ‘Collingwood on Philosophical Knowledge and the Enduring Nature of Philosophical Problems’, The British Journal for the History of Philosophy 12:1, 2004, pp. 93–109.