Pathways to Philosophy - ISFP Associate Award

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Oliver Leech

The Mind-Body Problem

Section One. Why the mind-problem is important

I took at myself in the mirror and see my body: skin, hair. eves, What is behind that outside appearance? A medical textbook explains that inside my body is a collection of organs — bones, muscles, a heart, a liver, lungs and, at the top, behind the eyes, a brain. Further enquiry reveals that all of my body, whether outside or insider is composed of cells — my body is indeed a composite of millions of cells which perform a great variety of different functions. The study of the nature and workings of the body, human biology, is a vast and complex subject. Now suppose that I knew everything there was to be known about human biology, the intricacies of the cell, the mechanics of all the systems, nervous, respiratory and so on. Suppose my knowledge of the body were complete in every conceivable detail. Would it follow from this that I knew everything about me? Put another way the question is this: am I the same as my body? Or is my body the sum total of me? Is a description of the body in all its detail a description of everything about me? Or is there a me in some sense which is not included in any biological analysis however meticulous and thoroughgoing.

At first impression there do seem to be elements of me which are outside the body's biology. A thought about tomorrow's weather, an idea about buying a lottery ticket, the smell of newly mown grass, the sound of a motorway, hunger, the memory of the shopping centre I visited yesterday, a decision to give up maple and pecan cookies. All these seem to be unique to me, part of me. They are all examples of what are called mental. states, that is, they exist in the mind but are not, at least not obviously, part of the body.

In Western philosophy there are three long-standing and well-supported responses to the problem of defining what this me really is: materialism, dualism and idealism. The way of the materialist is to describe all aspects of me in terms of physical things. The body obviously falls into this category. But for the materialist the mental states referred to above do not really exist separately from the body. If we continue to study them, according to the materialist, it will be found that they are not a special category made of some distinct non-material stuff but essentially physical substances described from a different point of view and about which some confusion of language has arisen. A thought, to the materialist, for example, is ultimately to be defined as some form of brain activity.

Dualism is the philosophical doctrine that physical things and mental states are both real but totally distinct and separate entities. The dualist (at least the strong dualist) rejects the idea that mental states can be, or in principle could ever be, reduced to or explained away in terms of physical things. To him mental states are completely separate in nature and origin: the universe is made not of one type of stuff (as the materialist believes) but of two: mind (the collective name for mental states) and matter.

Idealism, the third response, goes further than dualism. For the idealist, the direct opposite of the materialist, it is mental states, the mind, which are ultimate reality. Thoughts, ideas, feelings are real, matter is no more real than the phantom physical things we seem to touch and see in dreams. Material objects are projections of the mind, clusters of sense data which give the false appearance of being separate hard reality.

All three approaches face difficulties in giving a convincing answer to the question of what I am. Dualism, however. has an additional problem particular to it. Materialism and idealism share at least one claim, namely, that everything that exists, the entirety of the universe, is made of a single substance: where they disagree, of course, is in the nature of what that substance is. For the dualist, however, there are two discrete. real substances: the mental and the physical. The extra difficulty for the dualist is an obligation to provide an explanation of the relationship between mental states or consciousness and the physical world.

There are several possible relationships between the two, for example, one of interaction and one of parallelism. Interaction itself has subdivisions: two-way and one-way interaction. Two-way interaction entails that the body affects the mind and that the mind affects the body, so that, for example, stubbing your toe (physical) causes pain (mental), receiving a letter (physical) causes excitement (mental), being asked a question (physical) gives rise to a thought (mental). In each case an event in the physical world causes a mental experience of one sort or another. The other side of the two-way interaction is the power of the mind to influence the body in, for example, choosing to move the limbs, willing to stay awake when the body is falling asleep, expressing intentions through actions. One-way interaction would hold that the power to influence operates not in both but in a single direction, either from body to mind or from mind to body. Parallelism is quite different: it rejects interaction in either direction and claims that mind and body exist in separate domains, related to each other but not causally connected: each is independent of the other.

To return to dualism and the reasons for its declining popularity among professional philosophers. We recall that, although dualism needs a plausible explanation of the relationship between mind and body, its advocates have seemed unable to provide one. Parallelism, on the one hand, seemed out of touch. with reality. Interactionism, on the other, conformed more closely to immediate experience for we generally believe our minds both are affected by our bodies and also have the power to affect our bodies, But dualism rendered interaction impossible for the more it stressed that matter and consciousness were two totally different substances with contrasting properties and essences, the less scope was left for one to have any impact on the other. By making them alien to each other there was no common ground between them; neither could get any causal purchase on the other. Descartes was aware of this problem himself and proposed as a candidate for a meeting-point between mind and mater, the pineal gland whose function in his day was unknown. But of course, this is no answer. A gland whatever its function, is part of the biology of the body; it is made of cells and as much physical as a piece of granite.

The relationship of mind and body is not a dry academic question of interest only to a small coterie of university-based professional philosophers. Far from it. It is a question of central importance to anyone with a serious concern for seeking the truth about the human condition, to anyone who wants to know if there is a purpose to life, to anyone who wonders whether a religious teaching is founded on the truth about human beings, to anyone who questions the fundamentals of ethics and wants to live the 'good life'. It must. matter to us whether we are ultimately only a temporary congregation of atoms or a conscious being whose substance is not dependent on the continuation or the body. What could be more important questions than these? What am 1? Of what am I made? Where am 1 going? What is the right way to live? It is to these questions that the mind-body problem, with its ions history and vast literature is intimately related.

At the end of a review of Collected Poems by A. E. Housman. John Carey wrote the following:

Equally real for today's readers is his liberation from the consolations of religion. His view of mankind is astringent in its courage and modernity, We are chance collections of atoms. At death we will disperse to the four winds. Others will think our thoughts and breathe the air we breathed. Our sense of distinctive selfhood is mere Illusion.

What is really behind the reference to religion as 'consolation'? I suppose that What is meant is that reality is inexorably harsh and brutal and that those of a feeble mental disposition have run away from confrontation with it. Since they cannot bring themselves to face the full glare of its horrors, they have invented a fiction called religion, a story in which they are characters destined for a happy ending. And, furthermore, they have persuaded themselves that this fiction is no mere escapism but the ultimate truth of the universe. This will for self-deception is derived from their timidity and immaturity. By contrast, the brave, the resolute (Housman and his reviewer, presumably) look reality straight between the eyes, confront their own nothingness and, instead of striving to evade it in fairy-tale, bitterly but fully acknowledge it. So atheism is the response of the tough-minded, the courageous, theism of the weak-willed, of intellectual milksops; atheism a mark of the modern, of state-of-the-art philosophy, theism of nostalgic hankering after the pleasant certainties of a pre-scientific age; atheism is for real men, for rational grown-ups, who do not flinch at the discovery that life is fortuitous, purposeless, brief and succeeded by emptiness, religion for the immature who wallow in superstition and make believe, who prefer a Disneyfied, sanitised myth to science-revealed reality. In such a scenario who would not prefer to be counted among the SAS and paratroops rather than among the shrinkers and shirkers?

I have no problem valuing courage as a virtue. But isn't religion, real religion, not its ritualised derivatives, not its degenerate descendants and ecclesiastical institutions, isn't real religion exactly this, the search for truth whatsoever that truth may turn out to be and the endeavour to live a life in accordance with the undiluted discoveries of that search. Fundamental and central to this search is the question of what is the truth about the human condition, the question with which this chapter began. What am I? A chance and transient coming together of certain molecules? Or something more? Something not reducible to material ingredients? In the resolution of this question the mind body problem is paramount.

Section Two: Current views of the mind-body problem

It is widely assumed in scientific and philosophical circles that mind is only a temporary mystery, that it is only a question of time and research resources before a convincing description is given of how the brain generates consciousness, or how the mind has a physical basis or is a product of the brain or is simply brain activity described in different terms. The science that pursues this quest, the explanation for mind in physical terms, is neuroscience with its related disciplines.

The objective of the materialists is to express the sum total of what it means to be me in terms of the physical structure of the brain and, thereby, to eliminate a non-physical mind or any notion of a soul from descriptions of the self At the moment certain mental states are associated with certain areas of activity in the brain. The question is this: can this process of correlating be taken all the -way with the effect that every single mental event, whether of the senses, the, feelings, the intellect is correlated to a brain state. One method of pursuing this enquiry is to study people who have damage to the brain, If, ,when part of the brain ceases to function, there is a loss of some range of consciousness, then it is reasonable to assume that the missing part of the brain is responsible for the missing aspect of consciousness.

The mental and the physical are described in two different languages. For example.. in the language of the mind a person is in love, angry; in the language of the physical their condition might be described in terms of the electrochemical state of their brain, It is implicit in the materialists' objective to reach a position in which it is possible to translate all mental vocabulary into physical vocabulary.

The materialist project is sometimes seen in terms of robots, computers and artificial intelligence. The present mystery of consciousness is to yield to scientific enquiry and, in time, on the scale of decades and centuries perhaps, it is envisaged that a combination of biological systems and computers might be implanted in a toy with the effect that the toy had consciousness. According to this plan scientists would understand, then gain control of consciousness and ultimately be able to create it.

Modem students of the mind body problem almost without exception understand it to be about the attempt to explain mental states in physical terms. I have never heard anyone in contemporary philosophical debates put the question from the alternative starting point, that is, how may matter be explained in terms of consciousness. Here is a typical example of the prevailing view: 'how much of [mind] is a physical entity', asks a reviewer of Towards an Understanding of Consciousness by Daniel Dennett. He goes on: 'much of the function of the mind is built into the systems and organs of the body itself . taking it as quite uncontentious that mind actually has a function in bodily terms like the spleen or a kneecap. The question for this reviewer is what is the role of consciousness in a physical system not whether consciousness is capable of any role at all (see Section Seven). 'Our bodies possess minds,' he writes as though minds were things like cakes or handbags which could be owned, property to be bought or sold. Another reviewer of the same book asks what are the details by which 'physico-chemical processes are turned into consciousness' (Sunday Telegraph 11th August 1996).

Because a clear distinction (an ontologically unbridgeable gap) is not recognised between matter and consciousness, consciousness is assumed to have an as yet unexplained but an eventually explicable physical basis. It is seen as, in a sense, part of the body. Evolutionary theory is the prevailing biological and historical explanation of how plants, and bodies, both animal and human, came to acquire the form they now possess. Why do we have ears on the sides of the head, hair on its top, nails on fingers, necks which turn? To answer questions about functions of the body we look for any evolutionary advantage which they confer any help they may have provided in our history to enable us more successfully to survive and breed. It is understandable that if consciousness is considered to be part of the bodily system, there will be an assumption that it must have arisen in response to an evolutionary need. For this reason researchers ask what exactly is the biological value of consciousness. But of course such a question is only to be taken seriously if the physical nature Of consciousness is taken for granted and this is the very assumption that is in question here.

Two different entities tend to be confused here. It makes sense to enquire into the origin of the nervous system in animals and in human beings. A communication system by which information about the environment is received, processed so as to trigger a rapid motor reaction is a most valuable asset for a being in a struggle for survival. We are told that pain is warning of damage to the body. A flame bums the skin there is pain; because of the pain we act to protect the body by moving the limb from the fire' But this is precisely where we need to hold firm to the clear distinction between mind and body. Pain is an experience a mental state not part of the physical system. The limb is moved from the flame by the motor nerves which respond to the brain and the brain received information in terms of electrical messages from the sensory nerves. Consciousness, pain and all its other manifestations, is outside the causal system of the body. An explanation for the origin and development of the nervous system is plausible in terms of evolutionary theory; an explanation for consciousness is not.

There is more to the rejection of dualism, of course, than prejudice against the old-fashioned. Philosophy of the twentieth century regards the refutation of Cartesian dualism as one of its major achievements. The Cartesian view of the mind 'represents a deep illusion,' writes Roger Scruton in A Short History of Modern Philosophy. 'One of the most impressive features of recent philosophy has been the demolition of this body of doctrine and the consequent destruction of the dualist view of the world.' Anthony Kenny in The Oxford Illustrated History of Western Philosophy declares categorically that 'both of the great principles of Cartesian philosophy [the human being as 'a thinking substance' and matter as 'extension in motion'] were we now know false.' Kenny credits Descartes for what 'is still the most widespread view of mind among educated people who are not,' he adds dismissively, 'professional philosophers'. According to Kenny, Descartes' view of the mind, the first-person perspective whereby I have privileged access to the contents of my own consciousness, has been 'decisively refuted' by Wittgenstein, and 'his dichotomy of mind and body is. in the last analysis, untenable'.

The assumption that mind and brain are synonymous is pervasive in literature on the subject. In a book published in 1997 The Human Mind Explained, the Control Centre of the Living Machine, there Is no recognition that the capacity to control a machine might be incompatible with the concept of mind as an immaterial substance. In the foreword the author, Susan Greenfield, blithely writes.' These powers (of the brain] enable us to interact with a changing environment and to convey our thoughts and ideas to others' with no sense of anything mysterious or unexplained in that process. She moves like so many others, back and forth from the language of the physical to the language of the psychological as if there were no great divide between them. According to her we are 'empowered by our incredible mind.'

The relationship of the mind to the brain is a major focus of scientific research at the moment. In 1996 eight hundred scientists and philosophers gathered for the second biennial conference 'Towards a Science of Consciousness' in Tucson, Arizona. According to newspaper report the tone of the emerging science of consciousness was anti-religious. Note the dichotomy that is evident here. Consciousness is seen as a suitable topic for scientific study with the implication that it is as much physical as planets, minerals and organisms. What is rejected is equally revealing,, the association of consciousness as a non-physical entity with religious or spiritual concepts like an immaterial soul or incorporeal spirit. Andrew Brown, reporting on the conference for The Independent writes that 'dualism which would imply some 'soul-stuff or -spirit-stuff distinguishable from matter in which our real selves reside has been thoroughly rejected by both science and philosophy'. The view of philosopher John Searle neatly encapsulated in the slogan 'when the brain goes, I go' was considered widely typical of the conference outlook. Human personality was not any more considered as separate from the body, or superimposed on it but as something rooted in and growing in the brain.

Scientists and philosophers at the conference and elsewhere tend to divide into two groups: those who argue that consciousness is a hard problem essentially outside the- range of science and those who argue that it is a soft problem ultimately accessible to science. The hard school believes that a full understanding of how the brain works would not explain consciousness, which is a completely different nature. The soft problem school deny that there is any supernatural mystery of consciousness. For Daniel Dennett, author of Consciousness Explained, 'what you are...just is the organisation of all this competitive activity between this host of competencies which your body has developed' (New Scientist May 1996).

Section Three: The hard problem and the soft problem

In studies of consciousness a contrast is sometimes made (as mentioned in section two) between the hard problem and the soft problem. The hard problem is presented as either impossible to resolve and or merely as a much more difficult problem to resolve that the soft problem. David Chalmers in The Conscious Mind distinguishes between two distinct concepts of mind: the phenomenal, the conscious experience, 'characterised by the way it feels'; and the psychological, the basis of behaviour, characterised by what it does'. An understanding of the phenomena! aspect of mind is the hard problem, of the psychological, the soft problem. The distinction between the two aspects of mind can be illustrated as follows: I am listening to music, the direct. first-person experience of hearing the sounds is phenomenal consciousness, the auditory 'feeling', if you like; the effect of the music on my body, making me tap my feet in time is behavioural and taken to be caused by the 'psychological' aspect of consciousness.

I believe that Chalmers is right to draw a sharp distinction here. The objection I wish to raise is that the term, the 'psychological aspect of consciousness' is a misnomer. This objection is made on the grounds that everything categorised as consciousness under this heading is better explained in terms of neural behaviour, that is, of physical reactivity in which consciousness plays no part. The criticism of the position Chalmers takes at the beginning of his book is intended to help identify more accurately what is meant by consciousness, to put justified limits on its definition so that attention may be focused on what Chalmers rightly, in my view asserts is the key problem, the phenomenal aspect of consciousness.

The claim that the mind is causal in human behaviour should not be taken for granted no matter to what extent it is widespread and fundamental to the way we think about ourselves. The concept is implicit in Freudian psychology, in which, first, the mind can be both conscious and unconscious and, second, the unconscious mind can be a cause of activity. The very term an unconscious mind' is a self-contradiction if mind is defined as phenomenal consciousness. It is only when the presupposition is granted that mind can be influential in dictating bodily movements that the term makes any sense at all. But it is exactly that presupposition which I am calling into question here, Behaviourists in philosophy and psychology approached mind in a similar way in that they took it as uncontentious that mental states, if they were to be allowed independent existence at all, were to be defined as causes of behaviour or as dispositions to behave in certain ways. In its more extreme form, behaviourism discounted the phenomenal aspect of consciousness completely. More recently functionalism, a most influential philosophy of the mind body problem, defines mental states by their causal role: a pain for example, is that which, first of all, typical behaviour like treading barefoot on a drawing pin, tends to produce and that, second, which produces typical behaviour, like hopping around and rubbing the injured foot. The felt experience is not, to the functionalist, a distinct entity, requiring a distinct explanation. The functionalist is only interested in its role or function in behaviour. Freudian psychology, behaviourism and functionalism are part of a tradition which has in common the notion that mind is a term for what either totally or partially has power to initiate action to cause the body to move limbs, trunk, eyebrows anything under 'voluntary' control (or the case of the unconscious mind to cause non-voluntary behaviour). If it can be shown that all that falls under the heading 'psychological consciousness' should more sensibly be attributed to brain activity, that is, given a clear-cut physical basis, then the precise nature of the problem of consciousness will be identified more sharply and a more focused effort may be made to confront the questions about consciousness which Chalmers poses In the first chapter of his book. Questions like these: 'why does it exist? what does it do?'' how could it possibly arise from lumpy grey matter?'

Chalmers subtitles a section of his first chapter 'The Double Life of Mental Terms'. There is an ambiguity, he writes, in a term such as pain: on the one hand it denotes an unpleasant experience, directly felt; on the other hand, it denotes damage to the body from which remedial action, like rubbing bruised skin ensues; the first 'phenomenal, the second 'psychological'. Similarly, the term 'perceptions allows for two interpretations: the experience of seeing, tasting and so on, on the one hand, or the physical mechanisms of the sensory systems on the other; again the 'phenomenal' as distinct from the 'psychological'. Emotion too has a double aspect: the angry feeling which is 'phenomenal' as distinct from the flushed face and adrenaline surge. the 'psychological' counterpart.

Chalmers seems halfway to admitting that consciousness in the psychological sense is synonymous with explicable physical reactivity. He concedes that the physical, sciences have much to contribute, that, though the technical difficulties are very considerable, 'these problems ... have the character of puzzles rather than mysteries' but he still persists in confused terminology, a fuzzy overlap of the vocabulary of mind with that of body. To assert that 'the progress in the understanding of the mind has almost entirely centred on the explanation of behaviour' is to fail to recognise that the concept of mind influencing behaviour is deeply problematic.

But there is no need to make such dubious claims if the physical- and mental are clearly demarcated as follows. First, there is the problem of consciousness (,the hard problem), namely, why should there arise any feelings, thoughts, sensations at all when they seem to have location and no role in the physical world. And second, there is the problem of identifying causes of human behaviour, (mistakenly called a mind-body problem, whether 'soft or not) which is the proper province of science. In. an imaginary world in which all human behaviour and all brain states had explanations in terms of physics, chemistry and biology, the problem of phenomenal consciousness would remain completely untouched, its solution not a millimetre nearer. There are not two mind-body problems in the sense in which Chalmers and others mean but a problem for philosophy in making sense of consciousness and its relationship with matter and a problem for science in making sense of how the body in all its complexity functions.

Section Four: The impossibility of success for the materialist project

Is a materialistic explanation of mind even a theoretical possibility? Irrespective of the practical problems involved, is it possible to reduce everything at present called mind or consciousness and all it encompasses from pain to soul, from thought to spirit to a physical description? Here are three reasons for doubting such claims.

First, scientific experiments involve the recording and measuring of changes in physical objects; from these data general conclusions are drawn. Observing and reasoning are mental states; they are at one remove from the objects of observation and reasoning. When scientific discoveries are made, physical changes and movements are explained in terms of some deeper reality hidden from sight. An apple falls, an event observed many times, an invisible force, gravity, the object of reasoning not of sensory observation, is posited as the explanation for that movement. Litmus paper turns red in acid, another frequent observation, another conclusion reached. Observation and reasoning take place within consciousness. How could consciousness itself be the object, the 'thing' under scientific scrutiny for the scrutinising is itself a conscious activity?

There is no analogy between the scientific study of matter and a supposed scientific study of consciousness. In the former case the subject, consciousness, has an object, matter. In the latter case, subject and object would be one and the same. It is inconceivable that the same entity could simultaneously be that which studies and that which is studied. Another observing point of view would be needed, one a stage further back from consciousness from which position it could study consciousness. But this does not ease the problem. This-new observer would be outside the explanation and therefore require itself an explanation. And so ad infinitum. However many observers were accounted for, there must always remain one more where the account is given. I stand in a room of mirrors before and behind me. Into the infinite depth of the mirrors I see reflection after reflection of myself A me is staring at another me which is staring at another and so on. Consciousness can never explain consciousness.

Second, science is the growth of understanding. Since understanding is a mental state, science presupposes consciousness. The concept of one set of atoms and molecules understanding the underlying principles of other atoms and molecules is an absurdity. The distinction between true and false, between likely and unlikely, the recognition of meaning cannot conceivable be attributes of collections of coming and going, constantly-in-motion electrons.

Consciousness can never be explained in material terms for a third reason. What do we do when we give an explanation? We take an observation, a notion that is difficult to understand and relate it to those ideas which are within the understanding. What is a solar eclipse? We already understand how shadows are formed when an object impedes light. We have learned about the orbits of the moon, its position, vis-a-vis the earth and the sun, the relative sizes and distances from the earth of the sun and moon. The result of all this is a new understanding — an eclipse now makes sense. A confused concept has been clarified by reference to fixed points, of knowledge, pre-existing certainties. This can never be the case if the aim is to explain consciousness in terms of physical objects, For matter is not itself a certainty. Consciousness is the direct object of knowledge; it is that which we know first and foremost, directly and without mediation, With matter we can never have the same direct contact. We can never gain access to matter first-hand but only via the intermediary of our senses. Try to know the wall facing you and, do what you will, you can never pass beyond the experience of your own senses. Look at it, touch it, tap it — the senses of sight feeling, sound are stimulated. But these are experiences of sense data not of the wall. The concept of a wall is inferred from those sense data — the wall itself is not directly perceived.

In the case of the eclipse an initially strange phenomenon was referred to a framework of certainties, assimilated and 'given an explanation. In the case of consciousness and the project to explain it in terms of matter, there is no such framework. Matter, far from possessing the properties of substantial solidity is seen be a slippery, elusive concept in need of explanation itself. Can matter be explained in terms of consciousness is the real question, not the other way around.

Section Five: Mind-brain identity or mind-brain correlation

Year by year scientific investigation reveals an ever closer relationship between mind and brain. The case of those who believe that mind and brain are identical seems thereby to be strengthened. Look, they say, this brain damaged person has lost this particular aspect of consciousness or this man who suffered a severe blow to the head, as a result, has changed in personality. Doesn't it follow, they argue, that mind and brain are one and the same thing, that the mind is just another way of talking about the brain?

Not so, All such discoveries, all such changes in brains, in minds, in personalities are perfectly compatible with dualism of mind and body. Suppose we extrapolate fro 'in the present state of knowledge and assume that every single mental state from birth to death, every waking moment of life (and throw in dreams as well) is the after-effect of a physical condition. Does it follow that mind and brain are one? Not in the slightest. This extrapolation in fact consolidates dualism, and is no refutation at all. Imagine that the mind is a map of the brain (or part of it). Just as on an ordnance survey map every line, every colour and symbol has a direct correspondence to places on the land, so every mental state has a direct correspondence to a brain state. Every twinge of pain, scent from the kitchen, sound from the street, every grievance, anxiety, hope, internal conversation is a mark on the map and each of these mental states has as its counterpart a brain state, that is, the land covered by the map. If this were true, it would have no bearing at all on the dispute between dualists and materialists. Both could assimilate this one-to-one relationship within their description of the world.

In fact, the brain is not so constructed in such a way that each mental state can be related to a particular area of the brain. The analogy of the map oversimplifies the situation. It may be that many parts of the brain need to be in a particular configuration for a particular mental state to occur. The principle, however, remains unaffected. The fact, if it is indeed a fact, that for every mental state there is a prior brain state does not entail, nor even imply identity. Suppose the Bank of England raises the base rate and the following day the building societies raise the rate of mortgage interest. The Bank repeats this action and the building societies follow suit. Indeed this sequence happens time after time — for every base rate rise a subsequent mortgage interest rate rise so that there is a perfect correlation between the two. No one would claim on this basis that the base rate and the mortgage rate were one and the same thing. One hundred per cent correlation is not an argument for mind brain identity.

Section Six: The senses, consciousness and seeing

For most of every waking day of our whole lives, our eyes are open and we are .seeing. Seeing is part of almost everything we do. Under most circumstances we have no need to stop and consider it, to examine exactly what happens when we see. I believe, however, that there are two ways in which, if we do stop to consider it, seeing becomes a source of amazement: the first is the proper study of biology; the second confronts in an acute way the problem of consciousness and its relation to the brain. The complexity of the mechanics of the visual system of the human body is awe-, inspiring. In this section I am drawing attention to this complexity both on its own merits and also as a way of addressing the mind-body problem.

What happens when I look at a tree? Light reflected from the tree meets the cornea which is at the front of the eye and which bends the light to focus it. The light passes through the pupil which is a hole in the middle of the iris and adjustable in size. When light is intense, it contracts; when it is dim, it enlarges, a reflex reaction protecting the eye from light that is too bright and providing more light when it is difficult to see. Next light passes through the lens which 'fine-tunes' the focusing begun by the cornea. The lens too changes shape, controlled by a muscle, becoming thinner for distant objects and fatter for nearer objects. The light now focused throws an image of the tree on to the retina, which is a one-inch diameter collection of light sensitive cells situated at the back of the eye. These cells are of two sorts, rods which respond to black and white and cones which pick up colour. The cones, of which there are five to seven million, are of three types responsible, chiefly, for red, green or blue. It is at the retina stage in the process that light energy is turned into chemical energy.

It is clear that, first, in all the stages up to this point all reactions are totally mechanical, completely explicable as a cause-and-effect process and, second, that there is no seeing taking place yet. An eye on its own does not 'see' any more than a camera does. Indeed, the way in which light is focused through an adjustable aperture on to light sensitive material is reminiscent of the workings of a camera. (Or rather the other way round since man-made cameras are constructed as copies of the natural visual process.) A camera may receive an image but it has no experience of what seeing is, quite unlike the phenomenon of human or animal consciousness.

A rod cell is a minute but extremely complex piece of biological machinery. In length it is three five hundredths to one hundred and twenty fifth of an inch. At the end facing the front of the eye and so receiving the light, each rod cell contains 2000 discs lined up behind one another and containing 100 million molecules of a light-sensitive pigment called rhodopsin. In a thousandth of a second light transforms rhodopsin to metarhodopsin, the first in a series of chemical processes which culminate in the transmission by a synapse of signals to dendrites of adjacent cells, and from there eventually to the brain. At this stage the process resembles nothing that in the remotest way could be called seeing. At the retina was an image of the object of vision. Now, however, that image has been translated into the completely non-visual form of chemical information within cells.

The rods and cells convey their information to retinal ganglion cells which form the optic nerve. This enters the skull through a gap called the optic foramen. At a junction in the brain, the optic chiasma, fibres from the left side of the right eye join fibres from the left side of the left eye. The same happens with the right side of the eyes. On each side of the brain an optic nerve passes along an optic tract, that is, the one on. the left hand side of the brain with information from the left sides of the two eyes the one on the right-hand side of the brain with information from the right sides of the eyes. They reach a lateral geniculate nucleus, one on each side of the brain and from there to the primary visual cortex at the back of the brain where another series of processes takes place: the sorting of the visual data, the transmission of part of this information to other specialised regions nearby in the brain, the analysis and comparison of colours and contrasts. So demanding are the processes of vision that they occupy one fifth of the brain's capacity.

Described above is a very simplified version of an amazingly complicated set of processes. This operation, continuous all the time our eyes are open, is a natural phenomenon of staggering wonder. But where is seeing itself in the midst of all this chemical complexity? The experience is instantaneous. I shut my eyes, then open them. I don't have to wait for the image to be imprinted and chemically transmitted. It happens without any delay. so fast is the processing from cornea to cortex. But where is seeing in all this, the experience-of seeing itself'? What is it? How does it come about? What I mean by seeing is the felt phenomenon of seeing the tree. It seems that the explanation pursued above tells me a great deal about the biology of seeing but absolutely nothing about the experience of seeing. It does not even begin to explain what seeing is like as a mental event. It is this, the conscious experience, which the biological textbooks understandably ignore. It is not the province of science, of course but it remains a question of enormous significance. And it is precisely at this point that we encounter the essence of the mind-body problem and one reason why it has proved so intractable to rational enquiry. One can envisage that as time passes and research is extended ' biologists will be able to provide an ever more detailed and far-reaching analysis of the physical processes of vision but no matter to what level of complexity this description is extended by its very nature it will not include the, conscious experience of seeing. Seeing, that is,, the conscious experience, is not an object of scientific investigation.

It is very tempting to imagine that at the end of the biological process there sits an observer watching a screen on which is displayed an image of the external world in the range of the eyes, an inner person on a smaller scale, a homunculus to whom the whole visual show of life is presented. Unfortunately, there is no evidence of any such internal observer. Even if there were such an entity, far from resolving the problem it would simply repeat it. For, if a miniature version of me were watching a miniaturised screen, an account would need to be given of the physical processes by which reflected light from the screen impinged on the eye and triggered a series of responses in the homunculus brain with the result, that an experience of seeing took place. Clearly, this is the same problem presented earlier but on a smaller scale. The unrewarding prospect of an infinite series looms at this point in the argument as within the brain of the homunculus lives a micro-homunculus and within the brain of that — and so on. No, this is no answer to the problem of visual awareness, which remains daunting. How can it be that a continuous visual world evident in conscious experience arises out of the electrochemical circuitry of 'a slurry of tissue with the consistency of raw egg' (The Human Mind Explained Susan Greenfield). It defies rational explanation and yet it happens.

Furthermore, this discussion has confined itself to one sense, vision. In the case of all the senses the central mystery is the same. There is the biology: sensory input, neural transmission of information to the brain where it is assimilated, packaged and sent on. At the end of the process is the conscious experience, whether of seeing hearing, smelling, tasting, touching. The two seem intimately related and yet, also, totally separate. The intimacy of the relationship lies in the precise correlation of conscious experience to brain states; the sharp separation lies in the fact that excited neurons have nothing in common with mental states.

Section Seven: An attempt to define the relationship between mind and body

In a booklet on skin conditions produced by Boots, the chemists, after a discussion of causes of psoriasis, the following is added: 'There is also a link between drinking alcohol and psoriasis, but this is a trigger not a cause' [my italics]. In what way is this distinction between a cause and a trigger relevant to the problem of the relationship between mind and body? The precise nature of the relationship between the physical and the mental is the essence of this problem. Sometimes the case for physical states causing mental states is put in the strong terms of the brain causing or generating consciousness. The verb, to trigger, however, implies a much weaker sense of causal link. An examination of some of the vocabulary of causation might help to elucidate the mind-body relationship.

Let us think of the vocabulary of causation as a spectrum ranging from very strong to very weak. At the strongest extreme is the notion of creation. I take this term to mean the bringing into being out of nothing of something real and substantial. It is a power in this strict sense usually attributed only to God. The creation of the universe by God out of no pre-existing material contrasts with an alternative version according to which God makes or fashions the world from the pre-existing raw material of chaos.

Making is distinct from creating. In the making of a cake certain ingredients undergo a process of blending and heating which transforms their texture, colour, taste etc. Nothing new is created; initial resources are recombined into a new format. In the case of creation the law of conservation of mass and energy is broken; in the case of making the law it is respected.

Towards the other end of the spectrum is concept of triggering. To trigger is to set a process into action, to allow a potentiality to be realised. The explosive energy in the gun causes of its firing; the movement of the gun's trigger releases that power. A still weaker sense of cause is implied in the phrase to give rise to or in the verb to occasion. If I am on holiday in Miami and I ignore advice by straying into areas not considered safe for tourists, I give occasion to a mugging. Although I am certainly not the direct cause of being mugged, I do provide the opportunity. This is the sense meant in the Boots booklet: drinking alcohol is not the cause of the skin disease's latent existence but it brings into being the conditions in the body which allow the disease to break out. The law with its recognition of degrees of responsibility, for example, a sixty-forty division of blame in a car accident insurance case, acknowledges that there is a difference between cause in its stronger and in its weaker sense. If I cause another person's death with 100 per cent responsibility, I am more severely punished than if my responsibility is only partial as in manslaughter.

Perhaps the most subtle of relationships is the notion of a catalyst. Technically, in chemistry, a catalyst is a substance which is necessary for a chemical change to take place but which is not itself changed. The term has an ordinary language, metaphorical sense too. A counsellor, for example, holding discussions with a feuding husband and wife, might effect a reconciliation; all the necessary ingredients for a renewed relationship are already present but without the catalytic counsellor are not brought together. The concept of a catalyst is an intriguing one with its suggestion of a mysterious force at work, the connector absent from the connection, an elusive Scarlet Pimpernel of relationships.

Do any of these terms fit the mind-body relationship? The concept of creation can be quickly dismissed. I can think of no reason for believing that electrochemical changes in brains bring into being out of nowhere and nothing a conscious state. There is no capacity of material substances either presently known or conceivable in the future which might have that power. Besides, to assert that brains have the power to create consciousness would not in any case be a solution to the mind-body problem. Such a move would merely change the terms of the problem. The question now would be shifted to how particular conglomerations of matter, namely, the brains of animals and men, had a capacity which it would always be beyond the range of science to identify. Consciousness would remain just as much a mystery but the solution to it confined to an area where it could not possibly be discovered.

What of the concept of making? People make cakes, houses, cars, dresses. But all instances of making can be reduced to a process of reorganisation of material constituents. All the parts of the cakes, horses, cars and dresses can be traced back to ingredients which existed before the making process began. Even all musical compositions, however original, are new orderings of a limited range of notes. This sort of reductionism is clearly not applicable to consciousness. Consciousness just simply cannot be broken down into physical components. It is inconceivable that the felt experience of a smell or a thought could be analysed into bits and particles collected together from the physical stuff of the universe.

The concept of triggering seems to me a much closer model for the relationship between brain states and mental states. The contrast between the two states was sharply identified in the section on the visual process. Light stimuli sets in motion a series of reactions (cornea, lens, retina optic nerve, visual cortex) one physical connection after another. In some way that is outside scientific enquiry, there then follows the, mental stage, an experience of seeing. How can one get to grips with this relationship? It is clearly not causal for the reasons discussed above and this particular example of vision highlights the point. There is no common ground between the felt experience of seeing the colour orange and electrochemical stimulation of the visual cortex. It is almost as if they occupy different worlds.

I suspect that at this point all analogies of causation begin to break down. The reason for this is that by their very nature, when we told about cause and effect or an occasion and its consequences, our examples are inevitably drawn from objects which share physical characteristics. Mountains are the occasion for water to precipitate in rainfall. It is more precise to speak of mountains as the occasion rather than the cause of rain. If rain is caused in the sense of being made out something else, then it is made of water vapour. Mountains are the trigger for the change of state from water vapour to rain.

In a similar but not identical way the changed condition of the visual cortex is the occasion for the coming into existence or manifesting of the mental state of seeing. A relationship of occasion is a useful approximation, closest of terms in the vocabulary of causation. But there is a sharp distinction between an occasional relationship in the example of rain and mountains on the one hand and, on the other, mind and body. In the former case water vapour, mountains and rain are all physical objects: an account can be given of the effect of one on the other under the existing scheme of physics describing natural forces. The case of seeing is much more problematic. Here the relationship is not one of interacting physical objects sharing properties like extension in space, mass and volume. Only one side of the mind body dichotomy has such properties — we can certainly talk of the extension, mass and volume of the brain or parts of it. But none of these are properties of a mental state; the felt experience of seeing the colour orange has no extension, mass or volume. A mental state cannot, therefore, be assimilated into any system of physical measurement or assessment. This is my reason for claiming that a relationship described as one of occasion ' of giving rise to, is the best available in current vocabulary but not ideal and potentially misleading.

This point brings us back to the very core of the mind body problem and pointedly raises the key question once again. Just how can it be that an alteration to a highly complex physical construct can give rise to an event of mental experience? If we are expecting a solution easily accommodated within an existing scientific understanding of the world, then none is forthcoming. Indeed there is not the remotest possibility of one. Perhaps the last in the list above of descriptions of relationships is the most apt. In the very mysteriousness of the workings of the catalyst there is a parallel with the undeniable but inexplicable way in which change at the level of brain states is the invariable antecedent of change in mental states. In a sense it should not happen but it does.

When the eighteenth century philosopher, David Hume, analysed the problem of causation (in general terms and with no particular reference to the mind body relationship), he discovered that our common assumptions about cause are based on a misunderstanding. For if we go back to our empirical observations, we find that an event of causing is never observed. For example, we readily believe that the eating of bread is the cause of our being nourished. The only data we have as the basis for such a belief, however, is our observing the fact of eating bread and the subsequent fact of being nourished. A causal link is, not observed between the two events but is believed to exist not because of any process of reasoning but because of a habit of thinking. When we frequently observe a regular sequence of events (the eating of bread followed by nourishing, the sowing of seeds followed by plant growth, the motion of one billiard ball followed by the motion of others with which it has collided), there forms in the mind the belief that the first event is the cause of the second event. In other words there is around us a world in which many events occur in regular sequences; on to this world the mind projects the notion of cause, that event A is the cause of event B. Cause is an internal idea not an object of empirical observation, an interpretation of the world not a feature of it. Hume has a phrase for the regular sequences of events evident in the physical world. He calls them instances of constant conjunction.

Is it perhaps the case that constant conjunction is the most appropriate description for the relationship of brain states and mental states? For every mental state there is a preceding brain state. There is no causal connection between the two for the reason that they share no properties as argued earlier and because of a more general scepticism on the lines of Hume's position.

Section Eight: Three metaphors for mind

THE MAP

Think of the land with its woods, valleys, hills, roads, towns, the post office, the pub, the telephone kiosk, the museum, the youth hosted. Now think of a map of the land: green patches for woods, contours for hills and valleys, lines for roads and symbols for the post office, the pub and so on. For every feature on the land there is a representation of the map. The representation is symbolic and chiefly arbitrary.

The land in all its detail exists first: the map is made afterwards. The map does not affect changes on the land but changes in the land affect changes in map-making as cartographers need to alter old maps and make new ones to match this shifting landscape.

1 have an old map of the areas where I live. It shows the smaller towns, fewer roads, wider areas of woodland and farms of Victorian times than a map made last year. As the land became built up with more highways, streets, junctions, roundabouts, housing estates, factories ' office blocks, so the cartographers added more and more detail to the map. As the land became more complex, so did the map. But always it was the land which changed first and always the map which followed. Always the correspondence was perfect: for every landmark, a map mark.

Changes on the land are independent of changes on the map: they have their own causes in the progress of industry, the economic climate, the migration of population. The map is incidental to all this urban and rural flux. Changes on the land take place whether this map exists or not.

A metaphor for body and mind? Mind is the map of the body: brain states first, mental states afterwards; brain states with their own causes in the laws of nature governing the electrochemical motions of neurons, mental states corresponding to brain states but incidental to them.

MUSIC

The score is already on the stand when the musician walks on to the stage to warm applause. He bows to the audience, places the violin under his chin, raises the bow to shoulder height and looks down at the score, ready to be in his recital. There is music as the sonata passes through all of its phases to the coda of the final movement.

Before the performance begins the score is complete. The musician turns his eyes to read and plays in response. The score is sheets of paper on which is printed a stave; on the stave are printed notes and other musical symbols. The reading of a section of the score precedes the playing of that section of the music- always it is the score first, the music afterwards. The score determines which notes the violinist plays. When the notes move higher up the stave, the music that follows rises in pitch. Out of all the notes within the capacity of the ' violin and all possible combinations of them, out of all varieties of ways in which he might play them, the score requires a particular series of notes, their length, their rhythm, their dynamics. The result, a particular piece of music is heard, music that is related to the score in- this very precise form of representation.

Score first, music afterwards. In not the slightest way is the piece of paper showing the score affected by the musical sounds in the room. When it is taken from the music stand at the end, it is in exactly the same condition as it was when it was brought into the room. The musical sounds are completely incidental to the score. In one sense they might not exist for all the effect they have on the, score. (In another sense they are the reason for the existence of the score, its sole purpose.)

So it is with mind in relation to body. The paper and print of the score are the body; the music is the mind. The score shapes the particular characteristics of the music, makes it this unique piece of music not something else but it does not cause the music. The music follows the score but it exists separately from paper and print, in a different domain.

The music is both manifested and limited by the score. Before the performance begins all possibilities of musical combinations are available; the score allows a particular set of those possibilities to be expressed in: sound. But to express is to limit. These sounds are a barrier to other sounds which might be more, as they might be less beautiful.

Every mental experience we have, every ache and every thought arises in response to an already existing pattern in the brain. We have the experiences that our brain state attracts out of the unparticularised resource of potential consciousness.

THE WINDOW

In Section Eight the concept of a homunculus was raised only to be dismissed as an implausible solution to the mind body problem. There is obviously no biological basis for positing a miniature person within the brain who is aware of a virtual reality version of the external world in vision, sound taste, smell and touch as presented by the senses. The homunculus is both a scientific and philosophical non-starter The intellectual crudity of the homunculus idea does not mean, however, that consciousness cannot be the object of observation.

I look out through my window and see the garden. In fact, if I take the trouble, I can see both the garden and the window at the same time. Most of the time, however, I forget about the window and concentrate only on the lawn, the flowers, the shrubs. The window frames my picture of the garden. In a similar way there is a distinction between the conscious state in which I spend most of my day and a state where I have taken a step back from it to a point from which it can itself be the object of observation. To reach this point, one remove back from everyday life, requires an effort. To maintain this viewpoint for any length of time is a virtual impossibility.

The garden is the material world; the window is the medium of consciousness. This relationship shows why any knowledge about the physical world must first be mediated through consciousness. When I try to identify what exactly a material object is, to scrutinise its nature, I find myself in this state, that is, confronted directly by conscious experience as the raw material of reality, always a viewpoint, an angle . a perspective,, never the physical thing itself. In fact, the more I endeavour to identify what I mean by a physical object the more I find myself unable to pass beyond the barrier of my own sense experience.

Some people are aware of the window; some are not, vehemently denying that there is any such intermediary between themselves and things. N o amount of persuasion will change their views.

There are hints in his writings that Descartes was aware of this observing state of consciousness. In his Meditations he responds to a series of increasingly strong sceptical challenges to assert the initial certainty in 'his scheme of knowledge, that of his own existence: 'I am, I exist, is necessarily true. How does he acquire this certainty? By arguing that even if everything that occupies his mind were the false concoction of an evil demon (if there were no Europe, world or solar system; if he had no body) the truth must remain totally undiminished that he is conscious being, one capable of being the victim of such illusions. Whether or not he has satisfactorily proved his case is not the main concern here. Let us allow him that he has, that there is a self. What can be said about it'? Very significantly there is no reason to conclude from Descartes' argument that the self has a continuous existence, that is, that there was a self, the same self, five minutes age, five years ago or that it will persist into the future. Descartes can only be sure of his own existence at the moment at which lie attends to it. An admission of this is implicit in a fuller quotation from the Second Meditation: 'I am, I exist, is necessarily true, every time I express it or conceive of it in my mind'. It is not a necessary truth at any other time.

When the centre of consciousness shifts from involvement to detachment from being engrossed in things to being at a distance from things (when they are put at arms length by consciousness), then there is another dimension to experience. Feelings and thoughts and sense experiences become themselves the object of consciousness.