The man Psyche
The man Psyche
Author: John C. Eccles
Title: The Human Psyche
Subtitle: The GIFFORD Lectures University of Edinburgh 1978-1979
Publisher: Springer
Number of pages: 283
Year of production: 2012
Original Language: English
ISBN: 3642492541
ISBN-13(EAN): 9783642492549
ISBN: 3-642-49254-1
ISBN-13(EAN): 978-3-642-49254-9
"The Human Psyche" is an in-depth exploration of dualist-interactionism, a concept Sir John Eccles developed with Sir Karl Popper, in the context of a wide variety of brain activities relating to self-conciousness. Opening with a critical discussion of materialist hypo theses on this relationship, it aims to demonstrate the great explanatory power of dualist-interactionism in contrast to the poverty and inadequacy of materialist theories of the mind. This strong version of dualist inter actionism is demonstrated to be coherent and in general accord with present scientific knowledge.
The closing sections of the book show that dualist-interactionism offers valuable insights into the higher levels of human experience that cannot be accommodated to materialist theories of the mind – for example: the whole range of values; freedom of the will and moral responsibility; the uniqueness of the human person; the quest of meaning and for hope in the context of the inevitable end in death of this, our life on earth. This unique work, reaching far beyond the neurosciences, will be of profound interest to all those concerned with the workings and the products of the human mind.
John C. Eccles
The Human Psyche
The GIFFORD Lectures
University of Edinburgh 1978–1979
With 76 Figures
Springer International 1980
Sir John Eccles CH-6611 Contra (Locarno) TI, Switzerland Max-Planck-Institut für biophysikalische Chemie (Karl-Friedrich-Bonnhoeffer-Institut) D-3400 Göttingen, West Germany
ISBN-13: 978-3-642-492.54-9 e-ISBN-13: 978-3-642-492.52-5 DOI: 10.1007/978-3-642-492.52-5 Library of Congress Cataloging in Publication Data. Eccles, John Carew, Sir. The human psyche. (Gifford lectures; 1979) Bibliography: p. Includes index. 1. Brain. 2. Mind and body. 3. Neuropsychology. 4. Anthroposophy. I. Title. II. Series. QP376.E.266 128’.2 80-16980 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law, where copies are made for other than private use, a fee is payable to the publisher, the amount of the fee to be determined by agreement with the publisher. (C) by Springer-Verlag Berlin . Heidelberg 1980 Softcover reprint of the hardcover 1st edition 1980 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. 2120/3130-543210
From the Ode to PSYCHE by John Keats Yes, I will be thy priest, and build a fane In some untrodden region of my mind, Where branched thoughts, new grown with pleasant pain, Instead of pines shall murmur in the wind: And in the midst of this wide quietness A rosy sanctuary will I dress With the wreath’d trellis of a working brain, With buds, and bells, and stars without a name, With all the gardener Fancy e'er could feign, Who breeding flowers, will never breed the same: And there shall be for thee all soft delight That shadowy thought can win, A bright torch, and a casement ope at night, To let the warm Love in!
For Helena my Muse
Preface
In February and March 1978 I delivered my first series of Gifford Lectures in the University of Edinburgh. These lectures have been published under the title The Human Mystery. The second series of ten lectures were delivered from April 18 to May 4 1979 under the title The Human Psyche. As with the first series, the printed text is actually the manuscript prepared for those lectures, not some later compilation. The lectures were delivered informally, but based strictly on this manuscript. It is hoped that the printed text will convey the dramatic character of a lecture presenta tion. This book must not be regarded as a definitive text in neuroscience, psychology and philosophy, but rather as a series of ‘adventures of ideas’, to revive a Whiteheadean title.
The brain—mind problem has been the theme of three recent books: The Self and Its Brain; The Human Mystery (in its latter part); and now The Human Psyche. In this book there is critical discussion in the first lecture of the materialist hypotheses of the relationship of the self-con scious mind to the brain. In the subsequent lectures the strong dualist-interactionism developed in The Self and Its Brain is explored in depth in relation to a wide variety of phenomena relating to self-consciousness. The aim has been to demonstrate the great explanatory power of dualist interactionism in contrast to the poverty and inadequacy of all varieties of the materialist theories of the mind. It is not claimed that this strong version of dualist-interaction ism is thereby authenticated; but at least it is demonstrated to be coherent and to be in general accord with our present The brain—mind problem has been the theme of three recent books: The Self and Its Brain; The Human Mystery (in its latter part); and now The Human Psyche. In this book there is critical discussion in the first lecture of the materialist hypotheses of the relationship of the self-con scious mind to the brain. In the subsequent lectures the strong dualist-interactionism developed in The Self and Its Brain is explored in depth in relation to a wide variety of phenomena relating to self-consciousness. The aim has been to demonstrate the great explanatory power of dualist interactionism in contrast to the poverty and inadequacy of all varieties of the materialist theories of the mind. It is not claimed that this strong version of dualist-interaction ism is thereby authenticated; but at least it is demonstrated to be coherent and to be in general accord with our present scientific knowledge, which of course is not well developed in relationship to the phenomena of conscious experience. Moreover the last four lectures demonstrate that dualist interactionism offers valuable insights into the higher levels of human experience that cannot be accommodated to ma terialist theories of the mind. One can list for example: the whole range of values; freedom of the will and moral responsibility; the uniqueness of the human person; the quest for meaning and for hope in the context of the inevita ble end in death of this, our life on earth.
The exploration of the brain-mind relationship is based on the scientific study of the brain, both its structure and its physiological performance. So far as possible the ana tomical study has been based on the primate brain with particular emphasis on the recent demonstration of its organ ization in biological units or modules. Moreover on the functional side there are now remarkable studies on the human brain in perception, attention, intention, emotion, levels of consciousness, learning and memory. These studies have been carried out on normal subjects as well as on those with cerebral lesions, most notably commissurotomy. Thus the human psyche has been considered in a scientific manner in what we may call psychoneurology. In the later chapters the theme develops more philosophical overtones in relation to such topics as creativity, altruism, pseudaltru ism, aggression and values. Finally considerations of the purpose and meaning of self-conscious life lead to the cli max in the unifying concepts of the human psyche and its status in relation to God. Thus the whole lecture series can be considered in the words by Lord Gifford: “... to promote and diffuse the study of Natural Theology in the widest sense of that term – in other words, the knowledge of God’.
The last century of philosophical and religious catharsis has stripped mankind of the religious concept of the soul and the deeper spiritual meaning of personal life. The out come of this predicament tends to be hedonism or the nihil ism of despair. In these two series of Gifford Lectures there has been a re-examination and a criticism of the materialist and anti-religious philosophies that form so much of the The last century of philosophical and religious catharsis has stripped mankind of the religious concept of the soul and the deeper spiritual meaning of personal life. The out come of this predicament tends to be hedonism or the nihil ism of despair. In these two series of Gifford Lectures there has been a re-examination and a criticism of the materialist and anti-religious philosophies that form so much of the academic establishment in this age of disillusionment, domi nated as it is by science. It is not the purpose of these lectures to discredit science – on the contrary! But it is the purpose to attack and discredit Scientism, which may be defined as the effort to extend science beyond its proper sphere of operation. The arrogant claim of scientism is that science will soon in principle be able to provide a complete explanation of all our experiences, not only of the material world, but also of the world of our inner sensing in respect of values, of ideals, and of our most subtle and noble feelings of beauty, friendship and love as expressed and enshrined in the great masterpieces of human creativity.
The title of the book The Human Psyche was chosen because the theme progresses from a study of the brain– mind relationship as revealed in experimental neurology to the concept of the soul or psyche as originally expressed in the Platonic dialogues – in particular The Phaedo – and as further developed in Christianity. The Greeks symboli cally represented Psyche as the youngest of the goddesses. As such Psyche has inspired many artists. Most notable is The Story of Psyche painted by Raphael and Giulio Ro mano on the ceiling of the Loggia of the Villa Farnesina in Rome. Psyche has been the subject of one of the great odes by John Keats. The motive of this book is quoted from the last stanza of the Ode to Psyche. It reveals his subtle poetic thought on the brain—mind problem.
It is my hope that the philosophy expressed in these Gifford Lectures will help to restore to human persons a belief in their spiritual nature superimposed on their mate rial body and brain. With that restoration there will come a religious illumination giving hope and meaning to their ineffable existence as conscious selves. It has not been my task as a Gifford Lecturer to consider the details of religious dogmas and beliefs. But I have endeavoured to show that the philosophy of dualist-interactionism leads to a belief in the primacy of the spiritual nature of man, which in its turn leads ‘on to God’ as Max Planck so emphatically says (Quotation on p. 247). JOHN C. ECCLES.
Acknowledgements
I wish to express my thanks to the Gifford Lectureship Committee for the invitation to deliver the Gifford Lectures at the University of Edinburgh during the academic year 1978–1979. I would like to thank especially Professor Tom Torrance who initiated the invitation, our host, Professor J. McIntyre, the Acting Principal of the University of Edin burgh and Miss Jean Ewan, Secretary of the Gifford Lectureship Committee, for so efficiently and kindly making all arrangements before and during the lectures. I need not name the many friends who made the stay in Edinburgh so memorable for my wife and myself. I would also like to express my gratitude to my audience of up to 250 who provided an enthusiastic atmosphere, and who stayed the intensive course of 10 lectures in 2"/2 weeks.
Acknowledgements are given in the text for the many excellent illustrations that form an important part of such a wide ranging scientific presentation. My special thanks are due to Professor Rolf Hassler and Dr. Manfred Klee for so kindly arranging for the preparation of the illustra tions which was carried out so well by Hedwig Thomas and Jan Jaeger. Again the staff of Springer-Verlag has given very person al service in the publishing of this book. Dr. Heinz Götze has been a very good friend throughout the whole pub lishing operation, and I wish particularly to thank Dr. Thomas Thiekötter for his dedication and efficiency.
Contents
Lecture 1
Consciousness, Self-consciousness and the Brain—Mind Problem .......................................1
Résumé . . . . . . . . . . . . . . ......................................................................................................1
1.1 Introduction . . . . . . . . . . . ...............................................................................................2
1.2 Unity of Consciousness and Commissurot Orny . . . . . . . . . . . . . . . . ...............................5
1.3 Hypotheses Relating to the Brain—Mind Problem . . . . . . . . . .......................................16
1.3.1 Introductory Considerations . . . . . ..............................................................................16
1.3.2 Survey of Brain—Mind Hypotheses...............................................................................17
1.3.3 Critical Evaluation of Brain—Mind Hypotheses . . . . . . . . . . . . . ..................................19
1,4 Recent Proposals by Neuroscientists in Relation to the Brain—Mind Problem..................22
Lecture 2
2.1 2.2 2.3 2.4 2.5
Modules of the Neocortex and their Role in Dualist-Interactionism . . . . . . . ..........................27
Résumé . . . . . . . . . . . . . .........................................................................................................27
2.1 Introduction . . . . . . ............................................................................................................28
2.2 Modular Concept of the Neocortex ....................................................................................31
2.3 Modular Operation of the Neocortex . ................................................................................38
2.4 Liaison Between Brain and Mind .........................................................................................44
2.5 Summary and Conclusions on the Brain– Mind Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Lecture 3
Sensory Perception and Illusions ................................................................................................51
Résumé . . . . . . . . . . . ...............................................................................................................51
3.1 Introduction . . . . . . . ..........................................................................................................52
3.2 Anatomical Considerations .................................................................................................53
3.3 Physiological Investigations . . . . . .......................................................................................54
3.4 Psychological Comments . . . . . . ....................................................................................... 59
3.5 Visual Illusions . . . . . . . . . . . ................................................................................................59
3.5.1 General Considerations..................................................................................................59
3.5.2 Classification...................................................................................................................62
3.5.3 Cognitive Illusions.........................................................................................................63
3.5.3.1 Errors of Judgement...................................................................................................63
3.5.3.2 Completion Illusions ..................................................................................................65
3.5.3.3 Illusions Characterized by Ambiguity..........................................................................66
3.5.3.4 Attempted Explanations of Cognitive Illusions..........................................................67
3.5.3.4.1 Introduction.................................................................................................................. 67
3.5.3.4.2 Errors of Judgement ................................................................................................... 69
3.5.3.4.3 Completion Illusions.....................................................................................................70
3.5.3.4.4 Illusions Characterized by Ambiguity ....................................................................... 70
3.6 Depth Perception....................................................................................................................72
3.6.1 Stereopsis.............................................................................................................................72
3.6.2 Other Factors Concerned in Depth Perception.............................................................74
3.6.3 Impossible Figures............................................................................................................75
3.6.4 Attempted Explanations of the Illusions of Depth Perception.................................... 76
Lecture 4
Electrical Responses of the Brain ............................................................................................79
Résumé........................................................................................................................................ 79
4.1 Human Electroencephalogram . . . . . .................................................................................80
4.2 Event Related Potentials . . . . . . . .........................................................................................85
4.2.1 Evoked Potentials in the Neocortex . . ..............................................................................85
4.2.2 Attention . . . . . . . . . . . . . . ................................................................................................87
4.2.2.1 Introduction . . . . . . . . . . . ............................................................................................ 87
4.2.2.2 Experimental Investigations on Attention ....................................................................89
4.2.3 Influence of Attention and Intention on the Neural Machinery of the Brain . . ................96
4.2.4 Intention . . . . . . . . . . . . . . ...............................................................................................97
4.2.4.1 Introduction . . . . . . . . . . . . .........................................................................................97
4.2.4.2 Cerebral Correlates of Intention . . . . ............................................................................98
4.2.4.3 Neural Mechanisms of Intention . . . . ..........................................................................105
Lecture 5
The Emotional Brain . . . . . . . . . ...............................................................................................108
Résumé . . . . . . . . . . . . . . . ......................................................................................................108
5.1 Introduction . . . . . . . . . . . . ...............................................................................................109
5.2 Limbic System . . . . . . . . . . . . .............................................................................................110
5.2.1 Some Anatomical Considerations . . ............................................................................... 111
5.2.2 Limbic System and Emotional Expression ........................................................................113
5.2.3 Conclusions on Limbic System . . . . ..................................................................................116
5.2.4 Pharmacology of Limbic System and Hy pothalamus . . . . . . . . . . . . . ...............................117
5.3 Pain...........................................................................................................................................119
5.3.1 Introduction.............................................................................................................................. 119
5.3.2 Anatomy and Physiology of Nociceptive Pathways . . . . . . . . . . . . . . ................................121
5.3.3 Pharmacological Control of Pain . . . . ...............................................................................128
5.3.4 Neural Substrate of Pain? . . . . . . . ....................................................................................129
5.4 General Considerations of Other Affects . ............................................................................131
Lecture 6
Brain Activity and Levels of Consciousness..............................................................................133
Résumé............................................................................................................................................133
6.1 Introduction...............................................................................................................................134
6.2 Levels of Metabolic Activity in the Brain.............................................................................135
6.3 Electroencephalographic Studies of Neu ronal Systems that Modify Cerebral Activ ity.....41
6.3.1 Introduction.........................................................................................................................141
6.3.2 Reticular Activating System...........................................................................................142
6.3.3 Serotonergic Pathway....................................................................................................145
6.3.4 Noradrenergic Pathway.................................................................................................146
6.4 Sleep...................................................................................................................................147
6.4.1 Introduction.....................................................................................................................147
6.4.2 Electrophysiology of Sleep..........................................................................................147
6.4.3 Explanations of the Phenomena of Sleep...........................................................................153
6.4.4 Dreams........................................................................................................................155
6.4.5 Hallucinations.............................................................................................................156
6.5 Convulsions...................................................................................................................157
6.6 Coma and Vigil Coma.................................................................................................160
6.7 Anaesthesia...................................................................................................................160
6.8 Discussion on Brain Activity and Levels of Consciousness..........................................161
Lecture 7
World 3, Remembrance and Creativity...................................................................................165
Résumé..............................................................................................................................165
7.1 Introduction.................................................................................................................166
7.2 World 3.............................................................................................................................167
7.2.1 Initial Statement.............................................................................................................167
7.2.2 Objective Existence of World 3 ......................................................................................169
7.2.3 Relationships Between the Brain and World 3........................................................170
7.2.4 Artistic Creativity and World 3.....................................................................................172
7.2.5 Criticisms of the Objective Existence of World 3....................................................174
7.3 Remembrance...............................................................................................................176
7.3.1 Introduction..................................................................................................................176
7.3.2 Role of Modules in Cerebral Learning.....................................................................178
7.3.3 Conclusions...............................................................................................................187
7.4 Creativity..........................................................................................................................188
7.4.1 Creative Imagination in Science.......................................................................................188
7.4.2 Creative Imagination and Brain—Mind Problem...........................................................190
Lecture 8
Altruism, Pseudaltruism and Aggression..............................................................................193
Résumé..................................................................................................................................193
8.1 Introduction......................................................................................................................194
8.2 Genetic Inheritance...................................................................................................197
8.3 Kin Selection............................................................................................................. 200
8.4 Pseudaltruism........................................................................................................... 202
8.5 Altruism.....................................................................................................................202
8.6 Aggression.................................................................................................................208
Lecture 9
The Quest for Values and Meaning...................................................................................214
Résumé............................................................................................................................214
9.1 Origin of Values........................................................................................................215
9.2 Values in the Modern World........................................................................................219
9..3 Science and Values.....................................................................................................221
9.4 Conclusions with Respect to Values............................................................................225
9.5 The Meaning and the Purpose of Life..........................................................................226
Lecture 10
The Psyche, Freedom, Death and Immortal ity.................................................................230
Résumé...............................................................................................................................230
10.1 Introduction.................................................................................................................231
10.2 The Psyche (or Soul) ...................................................................................................234
10.3 Uniqueness of the Psyche..........................................................................................237
10.4 Freedom of the Will......................................................................................................241
10.5 Science and Religion..................................................................................................244
10.6 Death and Immortality?................................................................................................247
10.7 Epilogue........................................................................................................................251
References............................................................................................................................253
Subject Index.......................................................................................................................269
Lecture 1
Consciousness, Self-consciousness and the Brain—Mind Problem
Résumé
This lecture is partly in overlapping relationship with the last lectures of my first Gifford series. The usage of the word self-consciousness in contrast to consciousness is considered along with the problem of the development of self-consciousness out of animal consciousness. The experienced unity of self-consciousness is discussed in relation to the two cerebral hemispheres and in particular to the very recent results obtained by Sperry and his associates using the most subtle and sensitive methods for detection of self-conscious responses of the right hemispheres of commissurotomized patients. This ‘isolated’ hemisphere seems to have a limited self-consciousness in its recogni tion of faces and objects with appropriate emotional reactions. The various interpretations of these extraordinary results are fully dis cussed.
The second part of the lecture is devoted to a formulation of the several hypotheses relating to the brain—mind problem and to a critical discussion of the so-called materialist theories of the mind. Two reasons are given for rejecting the claim that these materialist theories are in accord with natural law as it now is. In addition it is claimed that all materialist theories are reducible to determinism which entails a negation of rational discussion. This theme is further developed in Lecture 10. There is formulation and discussion of the alternative hypothesis of dualist-interactionism that was developed in the Lecture 10 of the last series. Finally there is a critical evaluation of the diverse hypotheses formulated by neuroscientists in relation to the brain—mind problem.
1.1 Introduction
Last year in my Gifford Lectures (now published as The Human Mystery, Eccles, 1979a) I traced the line of contingency from the Big Bang to our existence here and now. From that wonderful series of happenings in all their mysterious sequences, I derived much of relevance to the over-riding theme of Natural Theology. The last three lectures dealt in some detail with the structure of the human brain, with conscious perception, with cognitive memory and finally with the brain—mind problem. This series of lectures is planned to continue logically from the first series by considering the wide range of manifestations of consciousness and their relation to the activities in the neuronal machinery of the brain. Hence it is advisable to overlap a little with the last series of lectures in order to establish a continuity of theme between the two series.
Following the procedure adopted by Popper and Eccles (1977) it is proposed to use the term self-conscious mind for the highest mental experiences. It implies knowing that one knows, which is of course initially a subjective or introspective criterion. However by linguistic communication it can be authenticated that other human beings share in this experience of self-knowing. One has only to listen to ordinary conversation, which is largely devoted to recounting the conscious experiences of the speakers. At a lower level there can be consciousness or awareness as indicated by intelligent learned behaviour and by emotional reactions. We can speak of an animal as conscious when it is capable of assessing the complexities of its present situation in the light of past experience and so is able to arrive at an appropriate course of action that is more than a stereo typed instinctive response. In this way it can exhibit an original behaviour pattern which can be learnt, and also which includes a wealth of emotional reactions. Reference should be made to the excellent accounts by Wilson (1975), Thorpe (1974), and Griffin (1976).
You may well ask: when does self-consciousness develop out of such a consciousness? A test for self can be identification in a mirror. Gallup (1977) has found that a chimpanzee can learn with difficulty to recognize itself in a mirror as shown by its use of the mirror image to remove a coloured mark on its face. Monkeys never learn in this way and there are no reported examples with other mammals. So it would seem that anthropoid apes have some primitive knowledge of self, but, as discussed in the last Gifford Lectures (Eccles, 1979a, Chap. 6), a fully developed recognition of self can only be demonstrated in the archeological records of ceremo nial burial by Neanderthal man some 80,000 years ago. It can be anticipated that further discoveries will place this critical time much earlier, particularly in view of the evidence from anthropoid apes.
But the above question has also to be asked for the developing human being. The investigations of Amsterdam (1972) lead him to give 18 months for the transition from the conscious baby to the self-conscious child.
Awareness is commonly used as a clinical term to signify that a patient is able to respond to verbal commands and to visual and cutaneous stimuli. One can also use the term self-awareness instead of self-consciousness, but I prefer self-consciousness because it relates directly to the self-conscious mind. However it must not be concluded that the use of this substantive term implies the recognition of mind as a substance in the Cartesian manner. Rather we can refer to mind as an entity. It comprises subjective experiences of all kinds and thus is identical with World 2 as defined by Popper (cf. Fig. 7-1).
The present series of lectures on ‘The Human Psyche' is necessari ly based on the full range of experiences that relate to the conscious self, though concepts of subconsciousness are also explored. There is still the tendency for materialist philosophers to denigrate the term “mind’ to “minding’ and to reject the substantive use of mind, as was done by Ryle (1949) in his influential book The Concept of Mind. It appeared at that time that the word mind had been finally exorcised, it being sufficient to characterize our experiences of human beings in descriptive terms of their actions and of their verbal behaviour. However Ryle was soon answered in a remarkable book by Beloff (1962) – The Existence of Mind.
Though the disciples of Ryle still actively promulgate reduction ism in the various materialist theories of the mind (Smart, 1963; Armstrong, 1968; Blakemore, 1977), there has been from the time of Beloff's book a remarkable reaction in a literature that ranges from a sober re-evaluation of the mind–brain relationships studied in various clinical conditions, for example in the writings of Penfield (1975), Sperry (1976; 1977), Zangwill (1976) and their associates to a veritable flowering of poetic imagery by Jaynes (1976), who begins his extraordinary book On the origin of consciousness in the breakdown of the bicameral mind by a paean of praise:
O, what a world of unseen visions and heard silences, this insubstantial country of the mind! What ineffable essences, these touchless rememberings and unshow able reveries! And the privacy of it all! A secret theater of speechless monologue and prevenient counsel, an invisible mansion of all moods, musings, and mysteries, an infinite resort of disappointments and discoveries. A whole kingdom where each of us reigns reclusively alone, questioning what we will, commanding what we can. A hidden hermitage where we may study out the troubled book of what we have done and yet may do. An introcosm that is more myself than anything I can find in a mirror. This consciousness that is myself of selves, that is everything, and yet nothing at all – what is it? And where did it come from? And why?
We can contrast this rhapsody with the testing procedures of experimental neuropsychology with its coloured patches or gratings, its pure tones and clicks, its taps and vibrations. These are techniques of analytic experiments and must not be regarded as revealing the initial stages, sensa, of the perceptual process, as if for example we sense a picture as a consequence of putting together small colour patches, as in a mosaic. On the contrary perceptions arise in con sciousness as fully formed pictures or as sounds of speech or music, being replete with meaning (Gibson, 1966; Thorpe, 1974). It is not of course denied that there are subconscious processes on the way to the conscious perception of pictures or sounds or felt objects of infinite variety, as we shall discuss in Lecture 3.
The brain—mind problem has now come into an exciting era where conference after conference brings together philosophers, psy chologists, psychiatrists, neurologists, neurobiologists and experts in machine intelligence. They declaim, they argue, they dispute and may even on rare occasions agree! Moreover there has been a rich variety of books as well as the numerous published texts of confer ences. The book The Self and Its Brain by Popper and me (1977) would seem to have achieved the doubtful distinction of being at the centre of a philosophical storm, as witness the spate of critical reviews aimed at it. It is all to the good that there is this revival of interest in the greatest problem confronting us – our nature and our destiny. Perhaps it is good that such emotions are aroused by irreconcilable confrontations.