Man can embody truth but he cannot know it.

––W.B. Yeats

This paper is concerned with the nature of the relation-ship between ‘mental’ mind phenomena and ‘material’brain phenomena; in other words the ‘mind–brain’ or‘mind–body’ problem. Following an examination of thegeneral nature of the problem, it establishes two workingpropositions which are employed in the attempt to con-ceptualize the mind in its relationship to the brain.

A second paper [1] will take these two propositions asa starting point, and explore their logical implications forpsychiatry, particularly in relation to theories of causal-ity and aetiology, and the question of how we achieveknowledge of the mind.

Mind and brain

It is an easy matter to define what me mean by the humanbrain in terms of its general physical characteristics, but a

definition of the human mind is more problematic. TheOxford English Dictionary [2] attempts definition in termsof various characteristics or faculties, such as memory,thought, intention, judgement and emotional experi-ence; mind is a ‘mental or psychic faculty’: ‘the seat ofawareness, thought, volition, and feeling; cognitive andemotional phenomena and powers as constituting a con-trolling system, specifically as opposed to matter’. Thefinal part of this definition reflects the common usage of‘mind’ as reference to something distinct from matter;the conception that lies at the heart of the ‘mind–body’problem. Probably no completely satisfactory, and cer-tainly no simple, definition of mind is possible. Whatwill be meant by mind in this paper is consciousnessawareness along with the sum of those mental facultiesregarded as characteristic of the mind, and in particularthe presence of a subjective state of which introspectiveawareness is possible. In his book The rediscovery of themind [3] the philosopher John Searle argues that what werecognize as fundamentally characteristic of the humanmind is the capacity for consciousness. Searle writes:‘I will argue that there is no way to study the phenomenaof the mind without implicitly or explicitly studying con-sciousness. The basic reason for this is that we reallyhave no notion of the mental apart from our notion ofconsciousness’.

Mind over matter? I: philosophical aspects of themind–brain problem

Paul Schimmel

Objective: To conceptualize the essence of the mind–body or mind–brain problem as oneof metaphysics rather than science, and to propose a formulation of the problem in thecontext of current scientific knowledge and its limitations.Method and results: The background and conceptual parameters of the mind–bodyproblem are delineated, and the limitations of brain research in formulating a solution iden-tified. The problem is reformulated and stated in terms of two propositions. These constitutea ‘double aspect theory’.Conclusions: The problem appears to arise as a consequence of the conceptual limita-tions of the human mind, and hence remains essentially a metaphysical one. A ‘doubleaspect theory’ recognizes the essential unity of mind and brain, while remaining consistentwith the dualism inherent in human experience.Key words: mind–body problem, mind–brain problem, philosophy.

Australian and New Zealand Journal of Psychiatry 2001; 35:481–487

Paul Schimmel, Consultant Psychiatrist

P.O. Box 37, Roseville, New South Wales 2069, Australia

Received 27 September 2000; revised 21 February 2001; accepted 2 May2001.

While a concept of unconscious mental processes isintegral to any sophisticated theory of mind, the ques-tions surrounding the epistemological status of uncon-scious processes within the mind, and how these mightbe conceptualized, lie outside of the scope of the paper.The term ‘mind’ will be employed without any implicitassumption about their existence and nature.

Historical background

The mind–body problem has a long philosophicalhistory. A brief note on some of the influential ideas mayhelp place the contemporary situation in perspective.

The French philosopher Rene Descartes (1596–1650)is known for his lucid formulation of ‘mind’ or ‘soul’ assomething distinct from body, and of which we haveindubitable knowledge [4]. Consequently he is often con-demned for ‘creating’, the mind–body problem. GilbertRyle [5] has suggested Descartes’ formulation contri-buted to the growth of a myth, which over time hasbecome a kind of official doctrine and dogma in Westernsociety; the dogma of ‘the ghost in the machine’. AlthoughDescartes gave clearer form to the dualist conception ofmind as distinct from matter, dualist systems of thoughtwere influential before Descartes and can be traced atleast as far back as the ancient Greeks.

Descartes considered mind or soul and body to be onto-logically distinct, that is, two things of different essentialnatures; yet his observation revealed that they seemed toexert effects upon one another. How could two thingsfundamentally different in nature act upon each other?Descartes postulated that the pineal gland was the seat ofmind–body interactions which he conceived of as beingmediated by the ‘animal spirits’, but beyond that wasunable to specify the mechanism by which such inter-action might take place [6].

Contemporary commentators, in highlighting the short-comings of Descartes’ dualism, often overlook the eleg-ance and clarity of his central formulation in theMeditations: I think therefore I am. Descartes, beginningfrom a position of epistemological scepticism, appre-hended reasons to doubt all commonly accepted forms ofknowledge, leaving only the apparently indubitablereality of his own consciousness as a given. There maybe grounds to doubt the existence of everything, hereasoned, but the very act of doubting implies at least the existence of one’s own mind. This much cannot bedoubted: ‘I am, I exist; that is certain’ [4]. Descartes thentook this acquaintance with one’s own mind as the rationalstarting point for establishing a system of ontology. Inhis Sixth Meditation [4] Descartes apprehended thatmental events, especially in the realm of understandingor intellect, appeared to constitute an area of discourse

distinct from physical bodily events; each area of dis-course possessing different explanatory parameters. InBertrand Russell’s words ‘“I think, therefore I am”makes mind more certain than matter, and my mind (forme) more certain than the minds of others’ and, ‘Thedecision . . . to regard thoughts rather than externalobjects as the prime empirical certainties was veryimportant, and had a profound effect on all subsequentphilosophy’. [7]

Since Descartes, formulations and attempted solutionsto the mind–body problem have been many and varied,but can be broadly divided into ‘dualist’, which assertthe existence of two sorts of ‘stuff’ (substances,processes, being) which coexist, and ‘monist’, whichassert the existence of only one fundamental ‘stuff’,which is the basis of all observable phenomena.

Dualist explanations may be further subdivided intointeractionist, such as Descartes’, and non-interactionist.The apparently implausible theory of ‘psychophysicalparallelism’, as found in the philosophy of Leibniz(1646–1716), provides an example of a non-interactionistdualist theory [8]. Leibniz postulated that there are twokinds of existence, body and mind, which parallel eachother but are completely separate and do not interact.Thus their apparent interaction is but an illusion; theconsequence of a preordained and ongoing harmony,established originally by God.

A dualist theory of historical importance, and continu-ing influence within psychiatry, is epiphenomenalism. Inphilosophical terms an epiphenomenon is a by-productwhich exerts no causal effect. Epiphenomenalism pro-poses that mind is a dependent and passive secondaryphenomenon caused by the activity of the brain. It isessentially non-interactionist, proposing a one-waycausality from brain to mind. Such a view constitutes arigidly deterministic formulation of mind, and its ascend-ance was contributed to by Darwin’s elucidation of deter-ministic principles in biology. The concept of soul, sointrinsic to much dualist thought, was threatened, and formany had been routed, by Darwin’s evolutionary theory.Epiphenomenalism found particular favour with Darwin’s‘disciple’ Thomas Henry Huxley, who seems to haveconceived of man as a kind of biological automaton [9].

Monist solutions fall broadly into three categories:idealist solutions which assert that the ‘stuff’ of the uni-verse is mind and its contents; materialist solutionswhich assert that the ‘stuff’ of the universe is matter andits properties; and attempts to formulate mind and matteras, in essence, identical, or as different aspects of a unity(this third category could be considered as subsumedunder the first two).

The name most closely associated with the idealistoption is Bishop Berkeley (1685–1753). Russell [10]

MIND OVER MATTER: PHILOSOPHICAL ASPECTS482

summarizes Berkeley’s position as a denial of the exist-ence of matter, maintaining that material objects onlyexist through being perceived. Thus physical bodies areregarded as not existing as such; it is only the ideas of bodies that exist in minds. Elsewhere [11] Russellacknowledges that because no absolute proof of theindependent existence of matter seems possible, idealistarguments are difficult to refute decisively. He neverthe-less attempts a commonsense refutation of Berkeley’sposition. He points to the counterintuitive nature of pureidealist theories and their lack of explanatory economyas good reasons not to embrace them. Although idealistperspectives have had great influence within philosophy,they have fared less well in the face of the growth ofempiricism in science, and the practical and pragmaticsuccesses that have flowed from the industrial and tech-nological revolutions.

It would probably be fair to say that ‘materialism’(as a philosophical/intellectual perspective) becamethe major influence in the West in the twentiethcentury, with attempted materialist solutions to themind–body problem asserting the primacy of matter.At the extreme the doctrine of materialism denies theexistence of mind. Such an assertion is, probably formost of us, difficult to accept, and might be considereddemonstrably false, in that something we call ‘mind’is apprehended through introspection and seems torequire explanation. A less extreme materialism mightregard mind as an epiphenomenon, or as something not remarkably different from the brain or body, andtherefore reducible to description in terms of physicalparameters.

In more recent times, through the perspectives pro-vided by modern physics, matter has begun to look less ‘substantial’ than it once did, and materialist per-spectives have developed into physicalist perspectiveswhich look towards the physical universe as a whole,that is, matter and the physical forces and propertiesassociated with matter, in the attempt to conceptualizethe mind.

The increase in the influence of materialist/physicalistintellectual perspectives was linked with the rise of empir-ical methods in the physical sciences, and positivism inphilosophy. In psychology, the outcome of the tendencyto ignore the mind was methodological behaviourism.The term behaviourism may be applied to a scientificmethod: ‘methodological behaviourism’, or to a philo-sophical perspective: ‘logical behaviourism’. The earlyproponent of behaviourism as an investigative method-ology in psychology, B. F. Skinner, in his book Scienceand human behaviour [12], exhorts his reader to forgetabout mental phenomena, which seem to be regarded asirrelevant. He writes that in certain situations ‘the mind

and the ideas, together with their special characteristics,are being invented on the spot to provide spuriousexplanations. A science of behaviour can hope to gainvery little from so cavalier a practice. Since mental orpsychic events are asserted to lack the dimensions ofphysical science, we have an additional reason for reject-ing them’.

In The concept of mind [5] the influential philosopherGilbert Ryle attempted to undermine the supposeddogma of the ‘ghost in the machine’, by arguing a formof ‘logical behaviourism’. Ryle suggests ‘. . . the stylesand procedures of people’s activities are the way theirminds work and are not merely imperfect reflections ofthe postulated secret processes which were supposed tobe the workings of minds’. Ryle also attempts to inval-idate Descartes’ concept of privileged access to one’s ownmind by arguing that self-knowledge and knowledgeabout others are on a parity: ‘The sorts of things that Ican find out about myself are the same as the sorts ofthings that I can find out about other people, and themethods of finding them out are much the same’. Whilethere is much commonsense here and, as Ryle argues, itseems probable that we obtain our understanding of theway others’ minds work from their behaviour, it is hardto see how Ryle’s arguments can do justice to the realityand dimensions of subjective mental experience. Anobserver’s understanding of a person’s behaviour cannever constitute a full knowledge of that person’s mind;there always remains an inaccessible and ‘ghostly’aspect in the experience of another. In order to fullyknow the nature of another’s experience of physical pain,I would have to feel his or her pain; presumably not apossibility (see below) (see also Wallace [13] for a cri-tique of some aspects of Ryle’s logic from within a psy-chiatric framework).

With the development of increasingly sophisticatedtechniques for direct brain investigation in the secondhalf of the twentieth century, the main focus for scien-tific investigation of mental states has shifted from theempirical observation of human behaviour, to the empir-ical observation of the brain. Research over the courseof the last century has provided increasing evidence forthe linkage between mental events and physical brainevents. Contemporary monist materialist views proposean identity between mental states and states of thematerial brain.

Today most of us would probably accept the proposi-tion that the existence of the mind is in some way con-tingent upon the existence and function of the materialbrain. We would regard the function of the mind as inti-mately and probably inextricably linked with the func-tion of the brain, and we would not expect a mind in theabsence of a functioning brain.

P. SCHIMMEL 483

The contemporary situation

If mental events are contingent upon brain events inthis kind of way, does that mean they are reducible tobrain events? Many scientists and philosophers holdsuch a view, and within psychiatry it seems a common-place assumption. There can be no doubt as to the influ-ence of reductionist materialist/physicalist perspectives,and the dominant view in the West in the latter half of thetwentieth century would seem to be a materialist ‘iden-tity theory’ which posits that mental events are in factbrain events, and may be fully explained as brain events,thus the title of Daniel Dennett’s book championing thisposition: Consciousness explained [14].

There have, however, always been voices arguing theimpossibility of a reductionist materialist understandingof mind. In 1960 the biologist Seymour Kety wrote inScience [15]:

There remains one biological phenomenon, more centralto psychiatry than to other fields, for which there is novalid physiochemical model and (or so it seems to me)little likelihood of developing one; this is the phen-omenon of consciousness – the complex of presentsensations and the memory of past experience which wecall mind.

He goes on to suggest that, ‘one can acknowledge theexistence of consciousness and of matter and energywithout insisting that one must be reduced to the other’.

Similarly the philosopher John Searle, in his recentbook, The rediscovery of the mind [3] identifies the ten-dency in materialist doctrines ‘to deny the existence ofany irreducible mental phenomena in the world’. Searleasks, ‘Now why are they [the reductionists] so anxious todeny the existence of irreducible intrinsic mental phe-nomena? Why don’t they just concede that these proper-ties are ordinary higher-level biological properties ofneurophysiological systems such as human brains?’Searle argues the need to accept the ‘obvious facts aboutour own experiences – for example, that we are all con-scious and that our conscious states have quite specificirreducible phenomenological properties’, is as neces-sary as the need to accept the ‘obvious facts of physics’.

Searle goes on to argue that the mistake is to view theirreducibility of mental phenomena and the contingencyof mind upon brain as incompatible realities whichtherefore imply a form of dualism. Searle asserts the irre-ducibility of mental events to physical events, but rejectsdualism.

David Chalmers is another contemporary philosopherunimpressed by attempts to formulate a reductive mater-ialist solution, but he is also unimpressed by Searle’sidea that the phenomenon of consciousness is an instance

of an ordinary higher level biological property, essen-tially similar to other higher level biological properties.Chalmers [16] points out that the phenomena of con-sciousness differ from all other phenomena in that: ‘Ourgrounds for belief in consciousness derive solely fromour own experience of it’. Chalmers argues that con-sciousness is not logically entailed by the physical factsof the functioning human brain; that is consciousness isnot ‘logically supervenient’ upon these facts:

From all the low-level facts about physical configur-ations and causation, we can in principle derive all sortsof high-level facts about macroscopic systems, theirorganization, and the causation among them. One coulddetermine all the facts about biological function, andabout human behaviour and the brain mechanisms bywhich it is caused. But nothing in this vast causal storywould lead one who had not experienced it directly tobelieve that there should be any consciousness.

Chalmers’ argument here seems analogous to the argu-ment entailed in the ‘problem of other minds’; that is theproblem of how we can ever know that someone else hasa mind. An observer may infer from a person’s behaviourand what he says about himself that the person is con-scious, but it is not something of which the observercan have certain knowledge, nor confirmation by directexperience of the phenomena of that consciousness; itis an inductive inference rather than a logical necessity.Similarly, an observer may monitor the activity of abrain, and infer that the brain possessed consciousness,but can have no direct knowledge of this consciousness.The observations about a brain which form the basisfor inference do not logically entail the existence ofconsciousness. Acquaintance with the existence of con-sciousness comes through one’s own experience.

Many scientists and some philosophers, such as Dennett[14], have asserted either that the mind–brain problemhas disappeared, or will eventually disappear, in the faceof the growth of scientific knowledge about the func-tioning of the brain; that the burgeoning knowledge, con-sequent upon advances in investigative neuroscience, hasfinally proved that the human mind and brain are indeedone and the same thing.

Despite the evidence for the existence of a close cor-relation or ‘identity’ between brain events and mentalevents, and despite the fact that this evidence has shapedthe way the mind–brain ‘relationship’ is conceptualized,there remains no consensus as to the correct understand-ing of the nature of this ‘relationship’. It is, I think, prob-ably mistaken to believe that growth in scientificknowledge can lead to such an understanding. That is tosay that the essence of the problem remains a matter ofmetaphysics rather than physics.

MIND OVER MATTER: PHILOSOPHICAL ASPECTS484

The problem

The assumption that the mind–brain problem willeventually be solved by science arises from a failure torecognize the nature of the problem. We already havesufficient grounds to assume, as a best hypothesis, thatmental events and brain events constitute a fundamentalunity; that there is at least an ‘identity’ of correlationbetween specific brain events or states and specificmental events or states. Ever since evidence for the linkbetween mental and brain events has been available,some kind of identity theory has seemed the most reasonable working hypothesis. The details of a sophis-ticated contemporary scanning study linking mentalactivity and brain physiology reveal nothing essentiallydifferent, in relation to the mind–brain question, fromsay, Wilder Penfield’s classic studies of cortical stimu-lation carried out more than 50 years ago [17]. Bothstudies provide data of the same explanatory order.Further scientific research is likely to reveal increas-ingly fine-grain data about the mind–brain relationship,but it cannot be expected to yield data of a new explan-atory order. Substantial evidence already exists for themind–brain correlation that would be predicted by someform of ‘identity’ theory, and it seems a reasonableassumption that further research will provide consistentdata.

The problem that science probably cannot reach is howto give a satisfactory explanation of mental experience,or the phenomenology of consciousness, in terms of thebrain. There does not seem to be a way. Any attempt atexplanation inevitably ends up leaving out the mind.

The difficulty may be stated something like this: evenif it were possible with sufficiently sophisticated scien-tific instruments to observe and measure all the neuro-physiological correlates of a specific mental event, forexample feeling a pain in the finger, this cannot commu-nicate the essential subjective experience of the pain tothe observer. An independent observer of these brainprocesses does not have a painful experience in his finger;he sees the various manifestations of neurophysiologicalprocesses. Even if he is aware that these manifestationsequate with ‘feeling a pain in the finger’, he has no directaccess to the subjective experience of the experimentalsubject, only indirect access, by inference, or from thesubject’s communications, about the experience. Anyempathic identification with the pain experience on theobserver’s part remains just that, not the thing in itself.There is, it would appear, no way to get the essence of asubjective mental experience by observing a brain; thisessence remains personal, and ‘ghostly’.

An hypothetical example (slightly modified) takenfrom Chalmers’ book The conscious mind [16] (adapted

from Jackson [18]), may help to illustrate this. Imaginewe live in an age of completed neuroscience, and knoweverything there is to know about physical processes inour brains. Mary has been brought up wearing spectacleswhich screen out colour, so she can see only black, whiteand grey. She has never taken them off and has neverseen any colour. Mary is nevertheless very well educatedas a neuroscientist specializing in the neurophysiologyof colour vision. ‘She knows everything there is to knowabout the neural processes involved in visual informationprocessing, about the physics of optical processes, andabout the physical makeup of objects in the environ-ment’, but she has never seen any colour. No amount ofreasoning from the physical facts that are known to hercan lead her to know what the experience of seeing incolour is like, for example ‘she does not know what it islike to see red’. ‘It follows that the facts about the sub-jective experience of colour vision are not entailed by thephysical facts. If they were, Mary could in principlecome to know what it is like to see red on the basis of herknowledge of the physical facts. But she cannot.’

In Chalmers’ terminology, the mind and experience are‘naturally supervenient’, but not ‘logically supervenient’,upon brain activity. Natural supervenience reflects thecontingency of mind upon brain; that in all probabilitythe mind cannot exist without the brain. Neverthelessexperience or mind is not logically supervenient, in thata full knowledge of brain events cannot lead to a fullknowledge of the subjective experience of the mind thataccompanies the brain. Or again, Chalmers comments,‘Whether or not consciousness is a biochemical struc-ture, that is not what “consciousness” means’.

In Levine’s terminology there is always an ‘explan-atory gap’ between physical explanations of brain pro-cesses and the nature of experience in the mind [19]. Thesubjective quality or ‘feel’ of experiences, referred toby philosophers as ‘qualia’, has a non-reductive aspect.Another way of putting this is that even if we assume ourconscious mind is our experience of the activity of ourbrain, and even if we adopt a theory of the unity or iden-tity of mind and brain, we do not and cannot, experiencemind and body/brain as identical.

Thus the problem that confronts us can be stated interms of two propositions (constituting a ‘double aspecttheory’) as follows:

1. The faculty of mind is contingent upon the function-ing human brain; in this sense mind and brain constitutetwo aspects of a unity. At a fundamental level thereappears to be an ‘identity’ between specific mental statesand specific brain states upon which they are contingent.

2. Any attempt to explain the subjective essence of amental state or process in terms of a brain state orprocess must inevitably fail as it leaves out the ‘mind’

P. SCHIMMEL 485

that we seek to explain. Discourse about mental states isnot reducible to discourse about brain states, and there-fore brain states and mind states are not identical. (If x isidentical to y then any property of x is also a property ofy, and vice versa. Subjective mental events and objectivebrain events have distinct and differing properties.)

Both these statements can, I believe, be reasonablyjudged to be true: the first on the basis that it best fits theavailable scientific data; the second on the basis that itis a self-evident truth. However taken together they aredifficult to reconcile; they result at best in a paradox, atworst in logical incompatibility. On the one hand we‘know’ that mind and brain in some fundamental wayconstitute unity, or exist in an ‘identity’; on the otherhand our experience of our own mind cannot be reducedto description of brain processes and nor can the essenceof mental experience be constructed out of knowledge ofbrain processes. How these non-identical constructs canbe an ‘identity’ remains mysterious.

Whatever the logical difficulty in reconciling thesetwo statements, it is no greater than the logical difficultypresented by other formulations, or ‘solutions’ to, themind-brain problem. As Wallace [13] comments, ‘Atthe current level of psychological, biological, and philo-sophical sophistication any approach to the mind–bodyproblem is scandalous; none avoids logical and empir-ical pitfalls’. The question continues to preoccupy philos-ophers precisely because no satisfactory solution hasbeen formulated. All attempted solutions to-date suffer a‘fatal’ flaw of incompleteness or internal contradiction,and the proposed formulation fares no worse in thisregard. Any greater plausibility of the proposed formula-tion over alternatives rests solely on whether one judgesthe ‘commonsense’ validity of the propositions to be suf-ficiently compelling.

If the arguments put forward here are accepted, thenwe are left with a mystery at the heart of the mind–brainrelationship; we simply cannot imaginatively grasp howmind comes about as a consequence of certain arrange-ments and activities of matter, but we know that it does.Furthermore, it seems unlikely that further scientificresearch, upon either brain or mind, can help us. If wetake Searle’s position then, despite the conceptual diffi-culties, we know the answer to our problem is that mindis a property of brain, and in principle this need be nomore mysterious than the fact that liquidity is a propertyof water under certain conditions [3]. Chalmers, in con-trast, believes that the situation is much more mysteriousindeed, and argues persuasively that consciousness is aproperty that stands in an altogether different relation-ship to the brain than liquidity does to water [16].

Even if we wish to avoid a dualist view we seem to bestuck phenomenologically with a sense of duality; we

simply experience mind and body as distinct. There is amystery at the heart of the mind–brain ‘relationship’,which it seems impossible for the mind to grasp, justas it appears to be beyond the capacity of the humanmind, at least in its current state of development, to imag-inatively grasp the concept of infinity. Regarding theproblem as amenable to solution by the means of scienceappears to have more to do with wish than reality.

Commentators in psychiatry often contend that the‘Cartesian’ distinction or ‘split’ between mind and body/brain is an artificial dichotomy and an imposition uponthe unity that constitutes reality, and exhort us to tran-scend this artificial distinction in our thinking. While itmay be necessary to strive to transcend this dichotomywhenever it threatens to limit clinical thinking, it doesnot follow that ‘dualist’ thinking is problematic in prin-ciple, and therefore something to be dispensed with. Inany case this is hardly possible. As has been argued, in order to think about the mind and its activity we needto have a concept of mind, and this inevitably involvesdistinguishing mind from either body or brain.

Our experience of duality would seem to be an un-avoidable consequence of the emergence of a self-awareand self-reflecting mind. I suggest that one cannot havea mind, at least not a ‘modern’ mind without it, andthat if we wished to do away with this sense of dualitywe would have to be willing to forego the capacity forthoughtful self-awareness that constitutes our mind. Forall the criticism that has been levelled at Descartes, hewas, in his willingness to take the mind seriously, essen-tially a modern thinker.

By this view the human ‘mind’, in a collective his-torical sense, is also a developing function, and prob-ably has different capacities today than it did, say, beforeDescartes’ time. This being so, the possibility cannot be excluded that, in its collective function, the humanmind could yet evolve to the point of possessing thecapacity to imaginatively grasp how it emerges frommatter.

Acknowledgement

I am grateful to the Melbourne philosopher TamasPataki for his helpful critique of this paper.

References

1. Schimmel P. Mind over matter? II: implications for psychiatry.Australian and New Zealand Journal of Psychiatry 2001;35:488–494.

2. Brown L, ed. The new shorter Oxford English Dictionary.Oxford: Clarendon, 1993.

3. Searle JR. The rediscovery of the mind. London: MIT Press,1994.

MIND OVER MATTER: PHILOSOPHICAL ASPECTS486

4. Descartes R. Meditations on first philosophy. In: Anscombe E,Geach PT, eds. Descartes’ philosophical writings. Sunbury-on-Thames: Thomas Nelson, 1970:59–124.

5. Ryle G. The concept of mind. New York: Barnes and Noble,1949.

6. Hatfield G. Descartes’ physiology and its relation to hispsychology. In: Cottingham J, eds. The Cambridge companion toDescartes. Cambridge: Cambridge University Press, 1992:335–370.

7. Russell B. Descartes. In: A history of Western philosophy.London: Counterpoint 1984:542–551.

8. Woolhouse RS, Francks R, eds. GW Leibniz – philosophicaltexts. Oxford: Oxford University Press, 1998.

9. Huxley TH. Animal automatism. In: Method and results: essays.New York: D Appleton, 1897: 199–250.

10. Russell B. Berkeley. In: A history of Western philosophy.London: Counterpoint 1984:623–633.

11. Russell B. The problems of philosophy. Oxford: OxfordUniversity Press, 1967.

12. Skinner BF. Science and human behaviour. New York: FreePress, 1965.

13. Wallace ER. Monistic dual aspect interactionism. Journal ofNervous and Mental Disease 1988; 176:4–21.

14. Dennett DC. Consciousness explained. London: Penguin, 1993.15. Kety SS. A biologist examines the mind and behavior. Science

1960; 132: 1861–1870.16. Chalmers DJ. The Conscious Mind: in Search of a Fundamental

Theory. Oxford: Oxford University Press 1996.17. Penfield W. The Mystery of the Mind: a Critical Study of

Consciousness and the Human Brain. Princeton, New Jersey:Princeton University Press 1975.

18. Jackson F. Epiphenomenal qualia. Philosophical Quarterly1982; 32: 127–136.

19. Levine J. Materialism and qualia: the explanatory gap. PacificPhilosophical Quarterly 1983; 64: 354–361.

P. SCHIMMEL 487