MONDAY, JUNE 25th 2007

1. I want to address an age-old problem, the relationship of body and mind, or more specifically, the brain and consciousness. At least since Descartes in the C17th philosophers have been grappling with this relationship. Descartes had argued for dualism, the notion that the body and the mind were two distinct substances, independent of each other but able to interact. Cartesian dualism had then and still has now a strong intuitive appeal – I think many people, perhaps most people, are instinctively drawn to a dualist way of thinking, holding the belief that they are n on-physical minds somehow housed in physical bodies. However dualism raises so many difficulties and apparent contradictions that it has been challenged time after time by later thinkers.

2. Nowadays the mind/body problem is not just for philosophers. It is a central study in psychology and of course neuroscience. The benefit we have in our age that was not available to Descartes is the ability to observe the brain by means of scanners with ever increasing accuracy and detail. But a problem we need to consider is this. Do we by virtue of knowing more about the brain also know more about consciousness? Is the study of consciousness – what it is, its origins, what it does - advanced in any way because it is possible to see what is going on in the brain of a person at the time that person is undergoing a particular conscious experience?

3. I want to start by listing several standard responses to the problem of the body/ consciousness relationship:

a. One response is that there is no problem. There is no problem because consciousness just is a physical feature of the brain and nervous system. This view is a development of a monist ontology, that is, the materialist philosophy that there is only one substance in the universe, namely matter and energy. Consciousness is in these terms reducible to a physical description; it can be encompassed in a physicalist worldview.

b. A slightly weaker monist response is to admit that at the moment physicalist explanations do not include an explanation of consciousness but, given time and money and sufficient research, a complete physicalist explanation will be forthcoming.

c. Third, some philosophers talk in terms of non-reductive physicalism. By this is meant that consciousness is part of the physical world but cannot be reduced to the physical. Consciousness is held to be a property of the brain or it supervenes on the brain

d. A third response is the claim that the mind/body problem is intrinsically insoluble on the grounds that it is beyond our intellectual range. One philosopher (Colin McGinn) uses this graphic illustration. Expecting human beings to solve the mind/body problem is like expecting armadillos to understand algebra: like them we lack the necessary intellectual capacity and apparatus. The hard headed physicalists like to dismiss supporters of this approach with the pejorative label of ‘mysterians’.

e. Other approaches have a different starting point: they take consciousness as the given, the fundamental ground of the enquiry. It is remarkable how radically philosophy has changed in the last hundred years. From Descartes in the C17th to at least major figures like Bertrand Russell and A J Ayer in C20th it was axiomatic that the study of reality should begin with our own conscious states and that the explanatory problem was proving from those conscious states that there existed an external world independent of the mind.

4. Bleary-eyed first thing in the morning you stub your toe on the bathroom door. Your face contorts, you wince, perhaps you utter an expletive, you rub your toe. An everyday event in many households at breakfast time around the world. Now analyse the event. Follow through the process from the cause, the contact between soft flesh and solid wood, to the behaviour in response: the wincing, saying ouch or rubbing the toe or whatever.

5. What is happening here? There is a diagram in Descartes of a boy reacting to burning his foot. Descartes – this is the first half of the C17 – sees the process in terms of wires or string-like connections. A message is delivered from the foot along the wire to reach the brain. Descartes sees the process in terms of wires or string-like connections. A message is delivered from the foot along the wire to reach the brain.

6. Think of those stately homes of centuries ago. Imagine that there are twenty or so rooms. Every room has a bell pull with which to call for assistance from the servants quarters in their base below stairs. The steward down there has a row of bells; each one is labelled with the name of the room where service is required. When the bell pull is used in, say, bedroom 5, the wire connecting it to the steward’s room tugs at the bell labelled bedroom 5. The steward notes the information and despatches a servant to the appropriate room. This is admittedly a crude over simplification but, for the moment, allow that when I stub my toe, my brain can detect which part of the body is damaged and (instead of sending a servant to the appropriate room) activates the motor nerves which instigate a range of muscles in the body which cause it to bend down and the hand to rub the damaged toe.

7. You may have noted an obvious disanalogy here. There is nothing in the brain, no central command unit, no equivalent of the steward. The brain does not have a homunculus, a tiny person in overall charge, receiving information and issuing instructions. There is no Captain Kirk equivalent at the console of the body receiving data and issuing orders. But leave that aside for the moment: that is certainly a problem but not the problem I want to concentrate on.

8. Of course what happens is much more complicated than the stately home analogy – there are many factors involved in the processing of information from the peripheral nerves and the response in motor nerves which operate the muscles and cause our responses, like rubbing the toe. But some sort transmission must take place from damaged tissue to the brain and from the brain to the muscles which control our behaviour. However sophisticated and complex we assume that there is a chain of causes and effects between the stubbed toe and the hand rubbing. It is a job of biological science to explain how it operates. Any explanation will be, presumably, a physical one. Science operates on the understanding that activity in the physical world is causally closed. What this means is that when any physical event takes place there is a physical cause for it. No matter what it is: the fall of a leaf, the explosion of a star, the growth of whiskers on a chin or a hand rubbing a toe, it does not happen out of the blue but as the consequence of something that preceded it. And that something will be a physical event. Nothing comes out of nothing, as the rationalists used to say.

9. Now at last I come to the point of this lengthy preamble. In all this system of action and reaction, of chains of cause and effect from toe to hand, where in all this is the pain. I had not mentioned the pain until now. Of course, stubbing your toe is painful; it really hurts. But in this physical explanation of the event there isn’t any mention of the pain. Where is it? What is it? How did it come about? What does it do? Pain is certainly real enough. What indeed could be more immediate, direct, certain and in your face than pain? We can talk in terms of all the physical features, of nerve endings, of information passing along the spinal column, of c-fibres firing without once coming across the pain itself. Pain does not seem to be included in the physiological explanation of the events; it seems to be outside the loop of the physical processes. Is the pain to be found in the toe, in the brain?

10. I am taking pain as an example of a conscious state, to represent for the moment the problem that besets attempts to explain consciousness in some sort of physicalist framework. The background that presents pain as a philosophical mystery also presents the experiences of all the senses as equally mysterious. The conscious experience of seeing of hearing or smelling and tasting are just as difficulty to accommodate within this physical framework. I want to run through five reasons for believing that consciousness cannot be explained in this way.

11. REASON 1: SPATIALITY All the physiological participants in the process: the nerves in the toe, in the spinal column, the neurons that are activated in the brain have particular locations. It is possible to point to them and ascribe to them a position in relation to one another. Physical things have a spatial location. Can we talk of a conscious state like pain as having a particular location? It seems prima facie that pain is not itself located in a particular place. The pain is not in the periphery of the body as we can show by applying an anaesthetic or by the strange phenomena of phantom limb pain. Is the pain in the brain? It may well be correlated with particular brain activity that is spatially l ocated but we are not entitled to move from correlation to any assumption about identity. We can try out the notion of spatially located pain by a comparison. We easily think of a nerve cell being adjacent to or at a distance from another nerve cell. But can we think of a pain being next to, spatially next to or at a distance from, say, another pain? Suppose you have a hangover headache at the same time as you stub your toe. Are the two near to each other or distant from each other? Can we use any terms of spatiality in connection with them? We could bring in other conscious states here. Could a pain be behind, in front of, underneath, above, inside, outside the taste of pineapple or the vivid sound of an oboe. We seem to have a problem with pain and with conscious states in general. They just don’t seem to be located in a particular spot in space. It is a problem that goes back to Descartes but you will also find it explored in contemporary philosophers of mind.

12. REASON 2: EXTENSION Take next another feature of pain. As well as not occupying a particular place, it doesn’t seem to have any measurements. Of course, we are here touching on a distinction famous at least since Descartes, between mind and body. Whereas physical objects are extended - indeed it is part of the definition of what we mean be a physical object that it is extended - states of mind are not. A nerve cell is such and such a distance across and deep and in length. Can we say that of the pain? How many inches, yards, miles, nano units – notice I do not even know what scale of distance to use - wide is a pain? How much does it weigh? How much water would it displace? We can easily see why the distinction between matter and mind in terms of extension as opposed to non-extension came about. Now we have two difficulties in the explanation of the conscious state of pain: it is apparently non-spatial and non-extended.

13. REASON 3: DIVISIBILITY Another distinction that can be traced back to Descartes. A physical object, whether it is a piece of wood or a nerve, can be cut in two: in short it is divisible. I can conceive of any piece of extended matter being split into smaller and smaller parts as far as the physicists say we can go, to quarks or whatever. But a pain - can you have half a pain? Is there any way that a conscious experience, a pain, a taste of pineapple, the sound of an oboe, could be split into parts. It is difficult to think of conscious states in terms of their divisibility. By contrast you might, however, say that a pain can increase or diminish in intensity; think of the difference between a dull ache and a sharp twinge, a sound can be softer or louder. So variability is something else that is different between physical things and conscious states. Physical things are divisible; conscious states seem not to be; conscious states seem on the face of it to vary in intensity a property we don’t find in physical things.

14. REASON 4: ENERGY TRANSFER All the energy in the exchanges from foot to cry of pain are accountable in terms of the exchange of energy. Pain is real; we surely have to concede that. But it seems to have arisen without the expenditure of any energy; furthermore, since rubbing of the foot action is caused by its physical antecedents (muscles, motor nerves), the pain seems to have no role in the causal process either. Pain: a mystery in two senses here: where it comes from and, what, if anything, it does. If we accept the law of the conservation of mass and energy, then there is as much energy in the system at Time 1, the damage to the toe as at Time 2, the rubbing of the foot. Nothing has been added and nothing gained. And yet in the meantime the pain has taken place. If any energy had been extended in the generation of pain, then there would be a loss of energy in the system. If the pain, had been the cause of the rubbing of the foot, then there would have been an addition of energy to the system. Again it seems that the conscious experience of pain is outside the loop of physical explanations.

15. REASON 5: PUBLIC/PRIVATE When you visit a doctor, he or she can hear you describing your pain and see any visible symptoms or listen through a stethoscope but what your doctor cannot do is experience your pain as you experience it. Pains are private to the person who experiences them; no one else can have this direct and immediate access to your pains or, for that matter, to your sense experiences, to your emotions, your desires, your thoughts, memories, imaginings, in short, to your consciousness. As for physical things, however, they are not private. They are open to public view to be observed directly, scrutinised, measured. The body and brain, they are physical objects too; latest advances in scanning mean that it is possible for others to observe the finer intricacies of the workings of the brain. Imagine that your brain is being observed and even being videoed by the best scanner money can buy. You are given a piece of pineapple to eat. Lo and behold the part of your brain that processes gustatory data starts to light up; some of your neurons are firing. They are detected on the scan; not only the researchers around the scanner can see that event taking place but on a webcam people all around the world can see your neurons firing. That is about as public an event as there can be. Just as in the film, the Truman Show, you could be the focal point of a programme of universal appeal. But the taste of the pineapple is totally inaccessible to all those people watching. Only I know the special quality of that taste. The experience is private to me; my brain, however, is public knowledge. How do we get from the public world of brain states and brain events to the subjective experience to which I have privileged access. Another great difficulty for any physicalist explanation.

Oliver Leech, June 25th 2007

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