Mind, Brain and Adaptation in the Nineteenth Century: Cerebral Localization and Its Biological Context from Gall to Ferrier
by
Robert M. Young
[ Contents | Preface | Introduction | Chapter: | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | Bibliography ]
INTRODUCTION
When you are criticizing the philosophy of an epoch, do not chiefly direct your attention to those intellectual positions which its exponents feel it necessary explicitly to defend. There will be some fundamental assumptions which adherents of all the variant systems within the epoch unconsciously presuppose. Such assumptions appear so obvious that people do not know what they are assuming because no other way of putting things has ever occurred to them. With these assumptions a certain limited number of types of philosophic systems are possible, and this group of systems constitutes the philosophy of the epoch.
Alfred North Whitehead, 1925, p. 71.
During the seventeenth century there evolved the scheme of scientific ideas which has dominated thought ever since. It involves a fundamental duality, with material on the one hand, and on the other hand mind. In between there lie the concepts of life, organism, function, instantaneous reality, interaction, order of nature, which collectively form the Achilles heel of the whole system.
Ibid., pp. 83-4.
. . . the point which I wish to make is that we forget how strained and paradoxical is the view of nature which modern science imposes on our thoughts.
Ibid., p. 122
In the conclusion of The Metaphysical Foundations of Modern Physical Science, E. A. Burtt stresses the implications of the scientific revolution for the study of mind and the behaviour of men and animals.
. . . it does seem like strange perversity in these Newtonian scientists to further their own conquests of external nature by loading on mind everything refractory to exact mathematical handling and thus rendering the latter still more difficult to study scientifically than it had been before. Did it never cross their minds that sooner or later people would appear who craved verifiable knowledge about mind in the same way they craved it about physical events, and who might reasonably curse their elder scientific brethren for buying easier success in their own enterprise by throwing extra handicaps in the way of their successors in social science? Apparently not; mind was to them a convenient receptacle for the refuse, the chips and whittlings of science, rather than a possible object of scientific knowledge. [l]
Around the beginning of the nineteenth century people did appear 'who craved verifiable knowledge about mind in the same way they craved it about physical events'. What hope did they have of succeeding?
1 Burtt, 1932, pp. 318-19.
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With what did traditional science provide them as a foundation on which to build? It provided them with a psychology modelled on the new physics and a series of dualisms which, if transcended, raised questions which no nice man would ask and which, when asked by not-so-nice men, led to philosophical absurdities. They apparently had little hope of success.
This book is an attempt to explain the problems faced by the early scientific enquirers into psychological phenomena; to trace some of the attempts during the nineteenth century to make psychology an experimental, biological science; and to indicate briefly the problems bequeathed to the present century by the early empirical investigators of the relations among mind, body and the environment.
The price paid for the scientific revolution in the physical sciences was the isolation of mind from nature and of the study of purposive behaviour from the advance of the scientific method. The fragmentation of the world into primary and secondary qualities, outer and inner, body and mind, and the exclusion of final causes from science have plagued the study of mind and behaviour at least since Descartes. This heritage provides the philosophical context for the present work. Cartesian dualism supplied an ontological basis for the separation of mind and body, while the theory of representative perception separated the knowing mind from its external object for knowledge. Pre-nineteenth century psychologists were thus preoccupied with the ontological problem of how (or whether) the mind could interact with the body on the one hand and with the epistemological problem of how a mind can know an object on the other. These metaphysical issues effectively precluded empirical investigation of the relations of mind and brain, the laws governing psychological and behavioural phenomena, and the relation of mental functions to the environment. Speculation and uncontrolled introspection filled the void.
From the Greeks came the speculation that the mind is made up of a series of innate powers or faculties which were localized in the hollow ventricles of the brain: Sensation and Imagination in the anterior chamber, Reason in the middle, and Memory in the posterior. When attention shifted to the solid parts of the brain, the faculties were speculatively localized in different areas by different schools. When the innateness of the faculties was challenged by the belief that there is nothing in the intellect that was not first in the senses, it was not the classification of the faculties which was questioned, but their origin. The question of the mind's role in the economy of the organism in its
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intercourse with the environment was not a central issue. Attention was diverted from this by the separation of the mind from the brain and from the external world, and the related separation of man from other organisms.
Given this prologue, it follows naturally that I have chosen to study the following themes in the history of nineteenth-century biology: (1) attempts to relate the mind to the brain by means of the concept of cerebral localization, and (2) attempts to specify the functions of the brain in the relations between organisms and their environments.
Both the empirical study of cerebral localization and the attempt to determine a set of functions which could explain the thought and behaviour of men and animals in their natural environments began with the work of Franz Joseph Gall (1758-1828). The first chapter of this book is a critical exposition of the last edition of Gall's major work, Sur les functions de cerveau . . . (6 vols., 1822-25), and an assessment of his place in the history of biology. While remaining agnostic on the philosophical mind-body problem, he thought he had discovered a method for demonstrating the correlation of innate faculties and identifiable brain areas. It is relatively incidental for present purposes that his 'cranioscopic' method led to the pseudo-science of phrenology and was abandoned in favour of experimental cerebral localization. The influence of his concepts and his empirical approach remain highly significant. Gall convinced the scientific community once and for all that 'the brain is the organ of the mind' and argued strongly that both its structure and functions could be concomitantly analysed by observation rather than speculation. His second major contribution lay in his rejection of the speculative faculties of Imagination, Reason, Memory, etc., as inadequate for the explanation of the differences among (1) species in nature, and (2) individual men and animals within their respective societies. He rejected the sensationalism of his contemporaries as irreconcilable with the facts of species and individual differences, and considered their classification of the faculties as irrelevant to the talents, propensities and needs of men and animals in their everyday lives. Gall's attempted classification of the functions of the brain remains significant, while the form in which he cast his psychology was that of the fallacious 'faculties', which point to important functions while begging the question of their origins and elements. Gall's third main contribution was to stress how much men and animals have in common: in his view they share 19 of the 27 fundamental faculties. It should be emphasized that Gall's biology was
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pre-evolutionary and that he accepted the prevailing concept of a static 'chain of beings'. However, in extending the comparative method to man he adhered to the continuous gradations in the chain more faithfully than those who had placed a wide gulf between men and animals. The influence of his approach and of some of his specific findings on later workers with a more adequate biological theory is considered in detail, while an attempt is made to clarify the limitations of his own static conception. As G. H. Lewes (an exponent of the implications of Gall's work) pointed out, by placing man firmly in nature Gall 'rescued the problem of mental functions from Metaphysics, and made it one of Biology'. 'In his vision of Psychology as a branch of Biology, subject therefore to all biological laws, and to be pursued by biological methods, he may be said to have given the science its basis.' [l]
Gall laid the foundations of empirical research into the relations of the functions of the brain to that organ and to the environment. However, once the empirical method replaces speculation, the relative merits of simple naturalist observation and of controlling nature by experiment become apparent. Those who came after Gall were quick to criticize his correlative and anecdotal method and to seek to learn more by direct intervention into the functioning brain by surgical excision-the method of ablation. Similarly, while Gall had a great deal to say on the psychological issue of 'What are the functions of the brain?' he made no contribution to the physiological issue of how the brain functions. His theory called for a one-to-one correlation between his faculties and cerebral 'organs', and Gall failed to seek the elements of which both the faculties and their cerebral bases were composed. In a sense he allowed his valid biological questions to dictate to the anatomy and physiology of the brain.
The history of brain and behaviour research after Gall involves the progressive acceptance and success of the experimental method in favour of his relatively crude correlations. Units into which both the physiology of the brain and its functions could be analysed were provided from the older psychological tradition: sensation and motion. This paradigm was applied to progressively higher parts of the nervous system from 1822 onwards. On the psychological side, the sensory-motor view was applied to mental processes by the school known as the Association Psychology. Gall's classification of the functions of the brain was abandoned, and most investigators reverted to those which
1 Lewes, 1871, pp. 425 and 423.
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he opposed. These, in turn, were viewed as complexes of associated sensations and motions. The question of the validity of cerebral localization provided the background against which psychophysical thinking occurred. Thus, the remaining chapters of the book are concerned with the rise of experimental neurophysiology from Flourens to Ferrier in the context of the association psychology, sensory-motor physiology and the theory of evolution. Pierre Flourens, François Magendie, and Johannes Mueller were the main exponents of the experimental method in research on the nervous system in the second quarter of the nineteenth century, and the relevant work of each is considered in some detail. Flourens provided the techniques which made brain research an experimental science. His findings, however, excluded the cerebral cortex from any role in motor functions and opposed localization of functions. His results provided the main support for the reluctance with which experimentalists applied the categories of sensation and motion to the organ of mind. The cortex and its functions were set apart from the analysis of the rest of the nervous system, and Flourens was explicit in his loyalty to Descartes and was vehemently opposed to Gall. Magendie began with different philosophical assumptions but also failed to transcend the older speculative approach to the higher functions. He maintained that their study was a branch of physiology, but the supposed physiological discipline involved was 'Ideology', the philosophical analysis of ideas into their sensory elements. However, while his conceptions looked backward where the functions of the brain were concerned, he laid the foundations for later work by providing an experimental basis for the functional division of the spinal nerve roots into sensory and motor. Mueller's experiments and his standard handbook set the seal of orthodoxy on Flourens' view of the cortex and Magendie's findings on the spinal cord. He also conducted one sort of analysis for sub-cortical functions and another for the cortex: the cortex subserved the Will, which (somehow) 'played on' the lower centres 'like the keys of a pianoforte'.
Concomitant developments were occurring in psychology which prepared it for integration with the new sensory-motor physiology. One aspect of the association psychology would fit it naturally for such an integration-its sensationalism. However, this same feature — reflecting the epistemological preoccupation of the tradition-looked back to the old philosophical context of associationism, with its roots in Locke and Gay and its development by David Hartley and the Mills. In the nineteenth century, associationists developed an interest
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in motion (and therefore behaviour) and brought this more balanced view into contact with the study of the nervous system. These developments occurred in the work of Alexander Bain, who did more than any other single figure to free psychology from its philosophic context and make it a natural science in its own right. The emphasis on learning as a consequence of doing (i.e., of motion) which he developed from the work of Müeller laid the foundations for the interest in behaviour which came to dominate psychology by the turn of the century. By means of an analysis of Bain's writings it is possible to trace the integration of the association psychology with sensory-motor physiology in principle, though Bain was still reluctant to apply the sensory-motor paradigm to the cerebral cortex.
Where Bain had enriched the association psychology with a new interest in motion and had provided it with an important alliance with experimental neurophysiology, Herbert Spencer gave it a new foundation in evolutionary biology. A detailed analysis of Spencer's intellectual development helps to show the emergence of the assumptions of modern psychology from elements of phrenology, associationism, sensory-motor physiology and the theory of evolution. Spencer's psychological work, like that of Bain, grew out of an early interest in phrenology. However, where Bain had turned away from the biological approach of the phrenologists, Spencer drew heavily on it to stress the relations of mental phenomena, and the needs of the organism, to the environment. Learning became the continuous adjustment or adaptation of internal relations to external relations. The shortcomings of Bain's work are presented by means of an analysis of his book on phrenology and the study of character, and Spencer's careful criticism of his work from the new viewpoint of evolutionary associationism.
Returning to the development of brain research, the conceptions of Bain and Spencer are brought together and applied to the cerebral cortex in the clinical neurological work of John Hughlings Jackson. New evidence for localization of functions is provided by the findings of Pierre Paul Broca (whose links with the methods and assumptions of phrenology are noted) and Fritsch and Hitzig. Broca's localization of the lesion in loss of speech (aphasia) provided the first convincing evidence of cerebral localization, while his correlative method and faculty psychology were criticized by the experimentalists. Fritsch and Hitzig proved the role of the cortex in muscular motions and demonstrated experimentally the electrical excitability of the cerebral hemispheres, both of which had been denied since before Flourens.
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Sir David Ferrier united the conceptions of Bain, Spencer, and Jackson with the findings of Broca and Fritsch and Hitzig and inaugurated the classical period of experimental cerebral localization. Ferrier played the central role in the localization of the cortical areas representing the five senses and numerous discrete muscular motions. These developments are briefly reviewed. More careful attention is paid to his attempt to derive a comprehensive psychology from sensory-motor psychophysiology. It provides an excellent vehicle for the examination of the problem bequeathed to the present century: how to relate biologically significant functions with a cortex organized in sensory-motor terms and psychological units of associated sensations and motions (which were soon to be viewed objectively as stimuli and responses).
Ferrier's classical work was completed by 1886. In the sixty years between the publication of Gall's work on The Functions of the Brain and the appearance of Ferrier's volume of the same name (in a second, much enlarged edition) the study of the brain and its functions had become an experimental science based on the theory of evolution. Concomitantly, mind had ceased to be viewed as an isolated substance, the role of which was representation of reality and the investigation of which was a branch of metaphysics. The study of mind had become a biological science concerned with an important function of the organism, and its role in adaptation to the environment was just beginning to be investigated. It will be seen that this book is an historical study which attempts to show the implications of philosophical assumptions as they affected, and continue to affect, the scientific writings of students of mind and brain. An attempt has been made to give a sense of period by the use of extensive quotation, contemporary commentaries, and reviews of the works of lesser figures.
The implicit conclusion of my argument is that a coherent integration of evolution and the study of man will not be achieved until the implications of the evolutionary principle of continuity and the concepts of function, adaptation, and utility are more consistently opposed to the legacy of Cartesian dualism on the one hand and the assumptions of the association psychology on the other. The wider context in which I hope my narrative will be viewed is the attempt to apply the categories of science to the interpretation of man's place in nature. Viewed philosophically, it attempts to show that the intervention of evolutionary theory failed to transcend the metaphysical commitment to the separation of mind from body and the related separation of man from the rest of nature. This is an aspect of a more general issue: the problem of
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finding some means of adhering to the assumptions of modern science as applied to man at the same time that the end of the tale gives us back a recognizable personal and interpersonal world. I hope that the book does show some of the ways in which a simple application of the ideas of corpuscular matter and motion to the study of mind, brain, and adaptation impoverished psychology. Beyond that I now feel that the problem of finding a way to transcend Cartesian dualism requires one to broaden the context of the enquiry to embrace the eighteenth and nineteenth-century debates on the principle of continuity which included natural theology, geology, and evolutionary theory as applied to the behavioural and social sciences.
In spite of the evidence which is offered in this book which indicates an integration of psychophysiology with evolutionary theory in the work of Spencer, Lewes, Jackson, and Ferrier, further investigation has shown that these developments were relatively isolated from the general evolutionary debate. In this study I have attempted to broaden the perspective within which certain aspects of nineteenth-century psychology, physiology and neurology should be viewed. At a later date I hope to place these developments within the context of the debate on man's place in nature, a debate which drew heavily on paradigms drawn from psychology, but the participants were unwilling or unable to concede that mental functions could be integrated within the general movement of naturalism with which the evolutionary debate was primarily concerned. It is hoped that this study, complemented by an interpretation of the broader movement, might serve as a basis for a philosophical critique of the conceptual limbo within which the behavioural and social sciences still find themselves. Certain aspects of this critique have already begun to emerge, and references to the relevant articles appear at the end of the bibliography.