Robert M. Young Online Writings
The Functions of the Brain: Gall to Ferrier (1808-1886)
By Robert M. Young*
THE BIOLOGICAL SCIENCES and particularly psychology have been made the wastebasket of the scientific revolution. In his classical discussion of The Metaphysical Foundations of Modern Physical Science, E. A. Burtt referred to the concept of mind as a convenient receptacle for the refuse, the chips and whittlings of science, rather than a possible object of scientific knowledge.
l A. G. A. Balz made the same point in his Cartesian Studies, where he noted that psychology "had to be whatever the new physics and the related metaphysics permitted it to be."2 A diagnosis of the limitations of the explanatory model of the scientific revolution has been made many times. The writings of Burtt and of A. N. Whitehead are but two examples of penetrating discussions of the difficulties involved in attempting to include biology, psychology, and the social sciences in the explanatory paradigm of the physical sciences.3 The prescriptions provided by these same authors show just how far we are from providing an alternative. It is arguable that a pre requisite to useful reconstructive work to repair what Burtt called "a rather radical piece of cosmic surgery"4 is at least a generation of careful historical research.5 In spite of Edwin G. Boring's admirable pioneer studies, this work has not yet begun.6Speaking of the seventeenth-century metaphysician-scientists, Burtt asks,
7Did 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?
Cartesian dualism and the doctrine of primary and secondary qualities enabled the physical sciences to develop, but this was achieved at the expense of the biological and behavioral sciences. The present study is an attempt to trace some of the im-
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* Whipple Science Museum, University of Cambridge. (For current address, see end of article.)
1 E. A. Burtt, The Metaphysical Foundations of Modern Physical Science (2nd ed., London: Routledge & Kegan Paul, 1932), p. 319.
2 A. G. A. Balz, Cartesian Studies (New York Columbia Univ. Press, 1951), p. 196.
3 Alfred North Whitehead, Science and the Modern World (Cambridge: Cambridge Univ. Press, 1925), Chs. 3, 6, 9.
4 Burtt, Metaphysical Foundations, p 302.
5 See my essay review on "Philosophy of Mind and Related Issues" in British Journal for the Philosophy of Science 1967 18: 325 330.
6 Cf. Robert M. Young, "Scholarship and the History of the Behavioural Sciences," History of Science, 1966, 5: 1-51.
7 Burtt, Metaphysical Foundations, pp. 31 319.
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plications of this world view in the scientific writings of psychologists and neurophysiologists in the nineteenth century. This topic was chosen because the relations among brain, mind, and behavior seem to be the obvious and crucial area for investigating the limitations of Cartesian dualism as applied to the biological sciences. It seems clear at the outset that the major difficulty of those who did crave verifiable knowledge about the mind was that they were very slow and timid about cursing their elder scientific brethren. By Cartesian dualism is meant, of course, the conception of two ontological substances: matter, which is extended, divisible, passive, and law-like; and mind, which is unextended, indivisible, active, and free. These substances were defined in such a way that any relationship between them seemed impossible in a metaphysical sense. The psychologists and physiologists were left with the problem of explaining how, in fact, impressions on the sense organs caused ideas, and thoughts caused movements, that is, how interaction occurred when it was metaphysically inconceivable.
Mind-body dualism played an important part in the period when attempts began to be made to apply the categories of science to the study of mind and brain. If attention is restricted to empirical investigation of these issues, one must begin in the nineteenth century, with the work of Franz Joseph Gall (1758-1828). After his doctrine has been considered, its relations with three other traditions will be outlined: first, the association psychology; second, the application of the categories of sensation and motion to progressively higher parts of the nervous system; third, a changing context for psychology, from a primarily philosophic approach within the static framework of the great chain of being to a biological approach based on the dynamics of evolutionary change. Thus, when the psychological principle of association was combined with the physiology of sensation and motion and integrated into a sensory-motor psychophysiology, this unified doctrine was almost immediately reinterpreted in terms of the theory of evolution as applied to mind and brain and to the relations between organisms and their environments. The body of the paper is concerned with a closely interrelated set of influences extending from early empirical studies on mind and brain to the establishment of experimental research on this topic. My aim is to suggest that when the study of the mind came to be considered in physiological and biological terms, powerful philosophic constraints were at work which narrowed the issue and impoverished the study of the mental functions of human and other organisms.
These developments occurred in the course of debates about the principle of cerebral localization, which may be defined as the doctrine that various parts of the brain have relatively distinct mental, behavioral, and physiological functions. For example, it is generally believed that the forebrain subserves intellectual functions, that just behind that is an area for the control of muscular movements, and that beneath the motor areas are a number of structures which regulate metabolic functions. Speculative localizations of functions date from Herophilus and Galen, that is, from the beginnings of anatomy and physiology. Various schemes of cerebral localization were proposed before the nineteenth century; for example, in the sixteenth century Gregor Reisch localized sensation, imagination, reasoning, and memory in the ventricles of the brain.8 After attention was shifted from the ventricles (and the associated pneumatic physiology) to the solid parts of the brain, the same faculties were variously localized.9
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8 H. W. Magoun, "Early Development Ideas Relating the Mind with the Brain," in G. E. W. Wolstenholme and C. M. O'Connor, eds., Neurological Basis of Behaviour (London: Churchill, 1958), p. 16.
9 A. Macalister, "Phrenology," in The Encyclopaedia Britannica (9th ed., Edinburgh: Black, 1885), Vol. XVIII, pp. 842-849; Jules Soury, Le Système nerveux central: structure et fonctions: histoire critique des théories et des doctrines (Paris: Carre & Naud, 1899), Vol. I; F. N. L. Poynter, ed., The History and Philosophy of Knowledge of the Brain and Its Functions (Oxford: Blackwell Scientific Publications, 1958).
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The work of Franz Joseph Gall provides the first empirical approach both to the nature of the faculties and to their localizations.10 The prevailing view just before Gall began his researches can be gathered from George Prochaska's Dissertation on the Functions of the Nervous System, published in Vienna in 1784, twelve years before Gall took his medical degree there. Prochaska argued that cerebral localization was probably valid, that the relevant faculties were the understanding, the will, imagination, and memory, but that "the conjectures by which eminent men have attempted to determine these are extremely improbable, and that department of physiology is as obscure now as ever it was;...''1l It is noteworthy that in 1799 Bichat still maintained confidently that the brain was the seat of the intellect but not of the passions.12 Gall insisted that the brain was the physiological basis of all mental functions.
Gall's ideas developed from childhood observations of his playmates. Those who could memorize better than he, had bulging eyes.l3 This was merely a physiognomical correlation, with no apparent physiological basis. Gall extended the correlation in two ways. First, he based it on a doctrine about the brain: bulging eyes were caused by a large underlying brain area for the faculty of verbal memory.14 Second, he argued that this faculty was innate — thus opposing the prevailing sensationalism of the idéologues.15 He generalized these points to argue that a science of human nature could be founded on four types of variables:
1 |
2 |
3 |
4 |
STRIKING implies FACULTY implies CORTICAL implies |
CRANIAL |
||
(talent, propensity, mania) |
(innate instinct) |
(activity varies with size) |
(size varies with underlying organ) |
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lO Francois Joseph Gall and J. C. Spurzheim, Anatomie et physiologie du système nerveux en général et du cerveau en particulier avec des observations sur la possibilité de reconnaître plusieurs dispositions intellectuelles et morales de l'homme et des animaux par la configuration de leurs têtes, 4 vols., with an atlas of 100 engraved plates. (Paris: Schoell, 1810-1819). (Gall is sole author of Vols. III and IV.) Gall, Sur les fonctions du cerveau et sur celle de chacune de ses parties 6 vols. (Paris: Ballière, 1822-1825). Gall, On the Functions of the Brain and Each of Its Parts: With Observations on the Possibility of Determining the Instincts, Propensities and Talents, or the Moral and Intellectual Dispositions of Men and Animals, by the Configuration of the Head, trans, Winslow Lewis, Jr., 6 vols. (Boston: Marsh, Capen & Lyon, 1835). Gall, et al., On the Functions of the Cerebellum by Drs Gall, Vimont, and Broussais, trans. George Combe (Edinburgh: Maclachlan & Stewart, 1838).
1l George Prochaska, A Dissertation on the Functions of the Nervous System, trans. Thomas Laycock (London: Sydenham Society, 1851), pp. 446, 447.
12 Xavier Bichat, Physiological Researches on Life and Death, trans. F. Gold (London: Longmans, n.d.), pp. 62, 252.
13 Gall, On the Functions of the Brain, Vol. I, pp. 57-58.
14 Ibid., p. 59.
15 Ibid., pp. 80-83, 95-171. See also Pierre J. C. Cabanis, Rapports du physique et du moral de l'homme, 2 vols. (2nd ed., Paris: Crapart, Caille & Ravier, 1805); François Picavet, Les Idéologues (Paris: Alcan, 1891); George Rosen, "The Philosophy of Ideology and the Emergence of Modern Medicine in France," Bulletin of the History of Medicine, 1946, 20 : 328-339; George Boas, French Philosophies of the Romantic Period (Baltimore: Johns Hopkins Press, 1925), Chs. 1 and 2; Madison Bentley, "The Psychological Antecedents of Phrenology," Psychological Monographs, 1916, 21: 102-115; Owsei Temkin, "The Philosophical Background of Magendie's Physiology," Bull. Hist. Med., 1946, 20: 10-35; Temkin, "Gall and the Phrenological Movement," Bull. Hist. Med., 1947, 21: 275-321 (on the idéologues, see esp. pp. 289-299). Temkin's article on Gall is the best secondary source available on this subject.
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Given this paradigm, Gall argued that the then-prevailing categories of interpretation — intelligence, reason, will, and so forth — were wholly inadequate to account for the obvious behavioral differences among species and individuals.l6 Where these categories stressed the relations between minds and objects for knowledge, Gall emphasized the adaptation of organisms to their environments.17 As he put it, "every hypothesis which renders no reason for the daily phenomena which the state of health and the state of disease offer us, is necessarily false.''l8 He argued that "the most sublime intelligence will never be able to find in a closet, what exists only in the vast field of nature.''l9 The implication was that psychology is not a branch of epistemology, but of general biology, and he devoted himself to making comparisons among the striking talents of men, the different habits and abilities of different species, and the compilation of a truly natural classification of functions.
Gall's findings and his influence played a seminal role in neuroanatomy and in the development of the concept of cerebral localization in neurophysiology and neurology,20 but in his own work it was undermined by his belief in "bumps" as accurate reflections of the relative size of areas of the underlying brain. This is only one example of a principle which Gall stated but which he was unable to carry out in practice. He established once and for all that the brain is the organ of the mind. Even Pierre Flourens, Gall's arch-opponent, granted this.2l His naturalist viewpoint, coupled with his critique of philosophical psychology, played an important part in removing psychology from philosophy and placing it in biology. Most important, however, was his argument that neither the study of the physiology of the brain nor the introspective study of mind would alone provide adequate categories for interpreting experience and behavior. Comparative studies of animals and observation of man in society — particularly the extraordinary (geniuses and maniacs)—were the essential prerequisites for arriving at a psychology which might explain mind, brain, and behavior.22
There is no reason to dwell on Gall's methods or the final formulation of his psychology.23 One concludes from a study of his large compendium of evidence for his faculties that the phrenological method is a textbook case in support of a falsificationist view of scientific method, for he sought confirmations and failed to take exceptions seriously enough.24 One should emphasize the value of his naturalist,
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16 Gall, On the Functions of the Brain, Vol. I., pp. 88-89.
17 Ibid., p. 84.
18 Ibid., Vol. V, p. 251
19 Ibid., p. 317.
20 Erwin H. Ackerknecht and Henri V. Vallois, Franz Joseph Gall, Inventor of Phrenology and His Collection, Wisconsin Studies in Medical History, No. 1 (Madison: Univ. Wisconsin Press, 1956), pp. 13-27. For Gall's contributions to neuroanatomy, see Owsei Temkin, "Remarks on the Neurology of Gall and Spurzheim," in E. A. Underwood, ed., Science, Medicine and History (London: Oxford Univ. Press, 1953), Vol. II, pp. 282-289.
21 Pierre Flourens, Phrenology Examined, trans. Charles Meigs (Philadelphia: Hogan & Thompson, 1846), pp. 27-28.
22 Gall, On the Functions of the Brain, Vol. III, pp. 133-135; Vol. IV, p. 162.
23 Gall discusses his methods in ibid., Vol. III, pp. 108-130.
24 This article is primarily concerned with the ways in which phrenology influenced developments in psychology and the study of the nervous system. A most interesting study of the parallel development of the phrenological movement in Britain, France, and America in this same period could provide a counterpoint to my rather Whiggish emphasis on the "winning side." For criticism of the cranioscopic method see Richard Chevenix, "Gall and Spurzheim—Phrenology," Foreign Quarterly Review, 1828, 2: 1-52; William Carpenter, "Noble on the Brain and Its Physiology," British and Foreign Medical Review, 1846 22: 488-544 (esp. pp. 520 ff. ); George H. Lewes, "Phrenology in France," Blackwood's Edinburgh Magazine, 1857, 32: 665-674. The reactions of phrenologists to criticism can be judged from reading almost any article in the Phrenological Journal. See also the list of phrenological controversies appended to Gall et al., On the Functions of the Cerebellum. The history of scientific physiology and psychology parted company with the practice of phrenological delineation (popularly known as "head-reading") over the legitimacy of the cranioscopic method. The history of applied phrenology formed an important part of the development of the scientific study of man by virtue of its wide popularity and its influence on Robert Chambers, A. R. Wallace, and Auguste Comte, among others. The American movement has received some attention. See John D. Davies, Phrenology Fad and Science: a 19th Century American Crusade (New Haven: Yale Univ. Press, 1955); David Bakan, "The Influence of Phrenology on American Psychology," Journal of the History of Behavioral Sciences, 1966, 2: 200-220. The British movement would repay closer study. There is a very large literature, and the influence of phrenology on evolutionary theory, various forms of social reform, and the behavioral sciences is very interesting indeed. In 1820 George Combe helped to found a phrenological society in Edinburgh and became its first president. By 1832 there were 29 phrenological societies in Britain and several journals in Britain and America. Their publications provide a most illuminating perspective on contemporary scientific developments. The British Phrenological Society was incorporated in 1899. It continued to publish a newsletter until 1966. The Society functioned until February 1967, when it went into voluntary liquidation. Its past president, Miss Frances Hedderly, F.B.P.S., has guided its affairs over the last few years and is now convinced that the work of the Society is completed. Its valuable library has been deposited at University College, London, and at the Whipple Science Museum, Cambridge. My research has been aided in many ways by the co-operation of Miss Hedderly and other members of the Society.
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biological approach in psychology but grant that the conclusions he drew invited the criticism which has been earned by all faculty psychologies: they substitute classification for explanation.25 To explain that a mother loves her child because she has a large cerebral organ producing a strong faculty of "philoprogenitiveness" is on a level with Molière's physician who explained the action of opium by invoking a "soporific virtue."26
Gall's anecdotal and correlative methods and his faculty psychology can serve only as object lessons in the misuse of scientific method. However, the obvious alternative — experiment — had failed to produce significant advances in understanding the functions of the nervous system until 1822, six years before Gall died.27 In his critique of the experimental method, Gall pointed out that it was difficult to repeat findings or to make inferences based upon, for instance, the sexual performance of an animal which was rapidly ceasing to live from uncontrollable loss of blood.28 However, these objections were rapidly overcome by technical and methodological developments, and one's claims for Gall are confined to the principles
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25 For criticisms of faculty psychologies see Carroll C. Pratt, "Faculty Psychology " Psychological Review, 1929, 36: 142-17; George F. Stout, "The Herbartian Psychology," Mind, 1888, 13: 321-338 and 473-498 and Stout, "Herbart Compared with English Psychologists and with Beneke," Mind, 1889, 14: 1-26; Charles E. Spearman, The Abilities of Man: Their Nature and Measurement (London: Macmillan, 1927), pp. 28 ff.
26 Cf. Galen: ". . . so long as we are ignorant of the true essence of the cause which is operating, we call it a faculty." On the Natural Faculties, trans. A. J. Brock (London: Heinemann, 1963), p. 17.
27 Pierre Flourens, Recherches experimentales sur les propriétés et les fonctions du système nerveux dans les animaux vertebrés (Paris: Crevot, 1824); J. M. D. Olmsted François Magendie (New York: Schuman's, 1944), Ch. 7.
28 Gall, On the Functions of the Brain Vol. III, p. 257. Cf. ibid., pp. 97-100 and 240-263; Vol. VI, pp. 153 and 239.
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mentioned in the preceding paragraphs and his prediction that the physiological experimenters ran the danger of reducing mental life to sensibility, irritability, and muscular motion.29 It will become apparent that he was most prescient.
In the experimental work which began to give significant results in 1822, the most important early sensory-motor physiologists were Pierre Flourens, François Magendie, and Johannes Müller. Their methods and some of their findings were very elegant indeed, but their analyses of the "organ of mind" were highly conditioned by their philosophical preconceptions. Flourens' careful methods of excision, control of bleeding, and observation of animals over long periods led to his classical findings on the regulatory functions of the cerebellum in muscular co-ordination and his location of the respiratory center in the medulla oblongata.30 Magendie demonstrated by experiment that the anterior spinal nerve roots are motor in function and the posterior roots are sensory. (The functional division between the anterior and posterior spinal nerve roots came to be known as the Bell-Magendie law, since Bell reached the same conclusion on anatomical grounds.31) Johannes Müller confirmed and extended these findings, and they were widely read in his classical Handbuch.32 In the period between 1822 and 1845 these three men were the leaders in establishing the experimental method in neurophysiology. Their work was a continuation of the investigation of physiological properties which was begun by Francis Glisson and made experimental by Albrecht von Haller.33 The discoveries which von Haller had made about the properties of the peripheral nerves they extended to the spinal cord and some higher centers. Furthermore, they adopted the paradigm of explanation — sensation and motion — which was to be progressively used to account for all nervous functions.
It is when one turns to the brain that the influence of philosophic constraints on their approach becomes apparent. Flourens' experiments on the brain involved successive slicing of the cortical substance without reference to the alleged cortical organs. Even if Gall's localizations had been true, this technique could only lead to successive loss of all functions.34 Flourens concluded that the cortex acts as one organ and that all its supposed faculties are indivisible. Thus the lower centers were for sensation and motion, while the cortex was a unitary organ for a unitary mind.35 The basis of this view is clear from the dedication of his Examen de la Phrénologie: "I frequently quote Descartes: I even go further; for I dedicate my work to his memory. I am writing in opposition to a bad philosophy [Gall's], while I am endeavoring to recall a sound one."36 It should be stressed that while Flourens'
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29 ibid., Vol. VI, pp. 160-161; cf. Vol. III, p. 245.
30 Flourens, Recherches expérimentales (2nd ed., Paris: Ballière, 1842). See also J. M. D. Olmsted, "Pierre Flourens," in Underwood, ed., Science, Medicine and History, Vol. II, pp. 290-302.
31 Olmsted, François Magendie, Ch. 7.
32 Johannes Müller, Elements of Physiology, trans. W. Baly, 2 vols. (London: Taylor & Walton, 1838-1842), Vol. I, pp. 640-646; cf. John T. Merz, A History of European Thought in the Nineteenth Century, 4 vols. (Edinburgh: Blackwood, 1904-1912), Vol. II, p. 384n.
33 Albrecht von Haller, "A Dissertation on the Sensible and Irritable Parts of Animals" (1735), trans. M. Tissot, reprinted with an introduction by Owsei Temkin, Bull. Hist. Med., 1936, 4: 651-699. Cf. Temkin, "The Classical Roots of Glisson's Doctrine of Irritation," Bull. Hist. Med., 1964, 37: 297-328. On the relationship between the concepts of Glisson, Haller, and Flourens, see Anon., "Recent Discoveries on the Physiology of the Nervous System," Edinburgh Medical and Surgical Journal, 1824, 21: 141-159, p. 144.
34 Gall, On the Functions of the Brain Vol. VI, pp. 164-166; Vol. III, p. 244.
35 Flourens, Recherches experimetales (1842), pp. xvi, 97, 208, 235, 243-244.
36 Flourens, Phrenology Examined, p. xiv; cf. pp. xi, xiii, 38, 45, 53, 57, 96.
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findings were not inconsistent with his interpretation of them, some of his extreme claims — for example, that the cortex is not the origin of any nerve — cannot be reconciled with the state of contemporary knowledge without allowing a large role for preconception.37 In the light of Gall's injunctions it is interesting to note that neither Flourens nor Magendie nor Müller — for all their emphasis on observation and experiment — made any attempt to determine the categories of function. They reverted to such traditional ones as memory, reason, and will.
Magendie's initial remarks about the brain were more promising: its study was a branch of physiology like the study of the functions of any other organ.38 However, when he specified what he meant by "physiology" in this context, a hiatus appeared, for the study of the physiology of the brain was identified as idéologie — the sensationalist analysis of mind which grew out of the work of Locke and Condillac and was then represented in Paris by Destutt de Tracy and Cabanis.39 These assumptions were, of course, different from Flourens' Cartesianism, but one result was the same: the analysis of the brain was separated from that of the lower centers. Will became a species of desire in the philosophy of the idéologues, but its cerebral basis was not directly connected with the cause of muscular contraction.40 Furthermore, the method used in this supposedly "physiological" investigation was introspection.4l
Müller, like Flourens and Magendie, rejected cerebral localization and the categories of Gall and separated the organs of mind from motor functions.42 As he put it in his Handbuch, "The fibres of all the motor, cerebral and spinal nerves may be imagined as spread out in the medulla oblongata, and exposed to the influence of the will like the keys of a piano-forte." It was impossible to determine how an exertion of the will excites these fibres.43
There is little point in multiplying examples of this separation except to emphasise that it became the accepted account. The standard British text, William Carpenter's Principles of Physiology, reiterates it through all editions, and he expounds it in his other writings right up to and including his review of the experiments of David Ferrier which decisively disproved it.44 The cortex was a unitary organ, "superadded" to the sensory-motor centers. The latter were said to be the instruments of the mind, and the mind's cortical organ had no connection with purely excito-motor actions.45 The motor aspect of this orthodoxy has been nicely summarized by Sir Geoffrey Jefferson:
From Haller . . . onwards to the best observer of them all, Flourens, and on again to Magendie and everyone else, all were agreed upon this, the brain was unresponsive except at the lower and lowest levels. The hemispheres were the seat of the "will"; they excited movements by playing on these motor mechanisms. But how they did so no one knew and no nice man would ask !46
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37 Flourens, Recherches expérimentales (1842), pp. xiii, 19, 22, 50, 237-239.
38 François Magendie, An Elementary Treatise on Human Physiology, trans. John Revere (5th ed., New York: Harper, 1843), p. 146.
39 Ibid., p. 147. See also references cited above, n. l5.
40 Ibid., pp. 151, 243-246, 252-253.
41 Ibid., p. 146.
42 Müller, Elements of Physiology, Vol. I, pp. 834-838, Vol. II, p. 1345; Flourens, Phrenology Examined, passim; Magendie, Elementary Treatise, p. l5On.
43 Müller, Elements of Physiology, Vol. II, p. 934.
44 William Carpenter, Principles of Mental Physiology (London: King, 1874), pp. 99-100, 715, 719.
45 Carpenter, "Noble on the Brain" pp. 5OO, 510-512, 515; Principles of Human Physiology (5th ed., Philadelphia: Blanchard & Lea, 1855), pp. 534-535, 489-490, 497-511.
46 Geoffrey Jefferson, Selected Papers (London: Pitman Medical, 1960), p. 116.
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We are left therefore with precise findings about the sensory-motor function of the spinal roots and some higher structures and an unphysiological doctrine about the cortex. When science has an unequivocal theory in one area and confusion in another, it is natural that an attempt will be made to extend the former to account for the latter. What was needed for the full exploitation of the sensory-motor paradigm of Bell and Magendie was a suitable theoretical context for bringing it into contact with psychology.
The theoretical context for sensory-motor physiology was provided by Alexander Bain. Bain was the heir to a psychological tradition which grew out of Locke and Gay,47 whose anti-Cartesian sensationalism was united with Newton's corpuscular theory of matter to provide the basis of the association psychology, first clearly formulated by David Hartley.48 The associationists specified atomic units for what Descartes considered to be indivisible mental substances. They argued that all complex mental phenomena could be analyzed into sensations and that the larger mental elements were built up by habit or repetition — the law of association.49
Association psychologists prior to Bain had seen their work in a philosophic context. Bain wrote psychology free from formal philosophy and set out to integrate the science of mind with physiology. In the Preface of the first volume (The Senses and the Intellect) of his major work he wrote, "Conceiving that the time has now come when many of the striking discoveries of the Physiologists relative to the nervous system should find a recognised place in the Science of Mind, I have devoted a separate chapter to the Physiology of the Brain and Nerves."50 He developed this approach on the basis of an early interest in phrenology before he was exposed to the influence of associationism through his relationship with John Stuart Mill.5l This mixture of influences led him to stress physiology but to abandon the faculty psychology of phrenology in favor of the principle of association and to reduce the phrenological faculties to, for example, ocular sensibility.52 He first reduced the numerous faculties to three — intellect, feelings, and will — and then analyzed these into associated sensations and motions. His chapter on the nervous system applied the sensory-motor paradigm to subcortical structures but stopped short of the hemispheres.53 Drawing on the work of Todd and Bowman,
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47 John Locke added a chapter entitled "Of the Association of Ideas" to Book 2 of the 4th ed. of An Essay Concerning Human Understanding (London: Awnsham & Churchill & Manship, 1690) to account for aberrant, unnatural, and habitual connections between ideas. The Rev. John Gay wrote an anonymous "Preliminary Dissertation concerning the Fundamental Principle of Virtue or Morality" which was appended to Edmund Law's translation of William King's An Essay on the Origin of Evil, 2 vols. (2nd ed., Cambridge: Thurlbourn, 1732). Gay employed the association of ideas and the pleasure-pain principle to account for the origin of the moral sense and all the passions, in lieu of considering them to be innately given instincts.
48 David Hartley, Observations on Man, His Frame, His Duty, and His Expectations, 2 vols. (London: Leake & Frederick, 1749).
49 For an excellent contemporary exposition of associationism, see J. S. Mill, "Bain's Psychology" (1859), reprinted in Dissertations and Discussions, Vol. III (London: Long mans, 1867), pp. 97-152.
50 Alexander Bain, The Senses and the Intellect (London: Parker, 1855), p. v. 51 Alexander Bain Autobiography (London: Longmans, 1901), pp. 27-28, 50, 90, 112, 215, 237-238, 259-260; On the Study of Character, Including an Estimate of Phrenology (London: Parker, 1861), esp. pp. v-vi, 16. Michael St. John Packe, The Life of John Stuart Mill (London: Secker & Warburg, 1954), pp. 289, 271, 291, 359.
52 Bain, On the Study of Character, pp. 147-150, 155-158, 177; Mill, Dissertations and Discussions, Vol. III, p. 110; Th. Ribot, English Psychology trans, J. Fitzgerald (London: King, 1873, p. 198.
53 In 1861 Bain said, "We must not, however, stop short of the hemispheres in our explanation of the control of the voluntary muscles ...." (On the Study of Character, p. 153), but this is the only passage in his writings which expresses this view.
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he extended the Bell-Magendie law a stage higher so that the thalamus was the highest sensory center and the corpus striatum the motor ganglion.54 From the physiological writings of Johannes Müller he adopted an emphasis on motion which was novel for the associationist tradition, whose stress on sensation had developed naturally from their interest in epistemology.55 This new emphasis provided psychology with a balanced sensory-motor view. Instead of concentrating on how we come to know through suffering experience, Bain inaugurated an interest in behavior which eventually became the dominant theme in behaviorist psychology — the concept of reinforcement.
In evaluating Bain's systematic treatises more broadly,56 one must conclude that associationism provided an inadequate explanation of the complex phenomena of emotion, instinct, and the biological functions which Gall had stressed.57 Also, while Bain attempted to correlate most of the functions of the brain with psychological processes, he left out the cortex and provided theories which had little contact with general biology.
Where Bain gave the association psychology a new emphasis on motion and a new alliance with physiology, Herbert Spencer provided it with a new foundation in evolutionary biology. Like Bain, Spencer derived his initial interest in psychology from phrenology and even wrote several phrenological articles and designed an instrument for measuring bumps.58 The psychological portions of his first book, Social Statics (1851), were based on a phrenological view of man and of adaptation.59 We are fortunate in having an essay written in his phrenological period and partially revised after he came under the influence of the associationists George Henry Lewes and John Stuart Mill.60 One can point with some confidence to the place in the text where his revision stopped, since the language shifts abruptly from associationist terms to phrenological faculties. 61
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54 Robert B. Todd and William Bowman, The Physiological Anatomy and Physiology of Man, 2 vols. (London: Parker, 1845), pp. 350-351; Bain, The Senses, pp. 40-47, 53, and 3rd ed. (1868), pp. 44-45.
55 Müller, Elements of Physiology, Vol. I, p. 828; Vol. II, pp. 931-950; Bain, The Senses (1855), pp. v-vi, 289; (1868), pp. 59, 64-73, 290-91, 296-306; cf. Mill, Dissertations and Discussions, Vol. III, p. 121.
56 Bain, The Senses (1855); The Emotions and the Will (London: Parker, 1859). 57 Bain's On the Study of Character was a failure. It went unnoticed by the critics and by Bain's contemporaries. There was no second edition. For criticisms of the adequacy of l9th-century associationism for explaining the phenomena of emotions and personality, see Mill, Dissertations and Discussions, Vol. III, p. 132; Ribot, English Psychology, p. 327; Gordon W. Allport, Personality. A Psychological Interpretation (New York: Holt, 1937), p. 87.
58 Herbert Spencer, An Autobiography, 2 vols. (London: Williams & Norgate, 1904), Vol. I, pp. 200-203, 225, 227-228, 246-247, 297, 378-379, 540-543, The Life and Letters of Herbert Spencer, ed. David Duncan (London: Methuen, 1908), p. 40; George B. Denton, "Early Psychological Theories of Herbert Spencer," American Journal of Psychology 1921, 32: 5-15; Jefferson, Selected Papers pp. 35-44.
59 Herbert Spencer, Social Statics (London: Chapman, 1851), pp. 5, 19-20, 32-38 75-89, 274, 280, 466.
60 Herbert Spencer, "The Philosophy of Style," in Essays: Scientific, Political and Speculative, 3 vols. (London: Williams & Norgate, 1901), Vol. II, pp. 333-369- Spencer Autobiography, Vol. I, pp. 225, 405. On the influence of Lewes and Mill, see ibid., pp. 378-379, 391-392, Life and Letters, pp. 418, 544.
61 The transition occurs in Essays, Vol. II, p. 360. The last sentence in associationist language refers to "mental energy" and "strain on the attention." The next sentence contains the first mention of "perceptive faculties." The MS in the British Museum appears to be a re-copy of the revised essay and neither confirms nor refutes my reading (MS, p. 113).
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The development of Spencer's theory of evolution is a fascinating but complex story.62 It grew out of phrenology, the study of zoology, and a contrary acceptance of Lamarck derived from Lyell's supposed refutation of Lamarck in the Principles of Geology. Rather than consider his general doctrine here, attention will be confined to its original context in psychology, that is, evolutionary associationism. Spencer argued for the continuity of all mental phenomena beginning with the contractions of the sensitive polyp and extending to the forms of thought. He also links the organism to the environment; psychology thereby becomes a biological science, and mind becomes an instrument of adaptation. Learning, in this new context, is the continuous adjustment of inner relations in the mind to external relations in the environment. If one suspends judgment on Spencer's "Lamarckian" mechanism, the relationship between associationism and evolution by the inheritance of acquired characteristics becomes one of simple extension. Habits are built up by the repeated juxtaposition of ideas in experience, and they are then transmitted as modifications in the nervous system. The tabula rasa of the individual is replaced by that of the race. This view allows Spencer to argue that the emotions, instincts, and faculties can be accounted for as stable phenomena for the individual, though their genesis is still explained by the experience of the species.
It was on the basis of these beliefs that Spencer criticized Bain.63 Bain had attempted a natural history of the mind, but the "nature" he consulted was the contents of his own mind — by introspection.64 Spencer argued that Bain should have relied instead on comparative and developmental studies and thereby become a genuine naturalist.65 In insisting on this, Spencer challenged a fundamental assumption of those psychologists who believed that philosophical and introspective analysis provides sequences and categories which can serve as a natural classification of mental life — that what we can arrive at by examining our own adult minds accurately reflects the actual synthesis in evolution and in individual experience.66 Plausible verbal analyses are replaced by biological observation and (later) experiment. Having said this, however, Spencer (and those who followed) failed to grasp its implications for psychology: the search which Gall had attempted for a genuine naturalism in the categories of psychological analysis.
Horace W. Magoun has claimed that there can be no question of "the predominant influence of Spencer upon Hughlings Jackson and, through him, upon the formation of evolutionary concepts of the organization and function of the brain in Western neurological thought."67 For his own part, Jackson considered his theories to be merely applications of Spencer's evolutionary associationism to the nervous system in the light of clinical evidence.68 There were two other important influences on Jackson's thinking. The first was Bain, whose motor theory was used by Jackson for a motor theory of speech, thus replacing the faculty concept.69 The second was
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62 This paragraph is expanded, with detailed documentation, in my paper on "The Development of Herbert Spencer's Concept of Evolution," Actes du XIe Congrès International d'Histoire des Sciences (Warsaw: Ossolineum, 1967), Vol. II, pp. 273-278.
63 Herbert Spencer "Bain on the Emotions and the Will" (1860), in Essays, Vol. I, pp. 241-264.
64 Ibid., pp. 242, 244, 247, 257.
65 Ibid., pp. 249-252.
66 Ibid., pp. 254-256.
67 Horace W. Magoun, "Darwin and Concepts of Brain Function," in J. F. Delafresnaye, ed., Brain Mechanisms and Learning (Oxford: Blackwell, 1961), p. 17.
68 Selected Writings of John Hughlings Jackson, ed. James Taylor, 2 vols. (London: Hodder & Stoughton, 1931), Vol. I, pp. 147 n., 238n, 375; Vol. II, pp. 40n, 42, 45, 80n., 98, 346n., 395, 431-432.
69 Ibid., Vol. I, pp. 167-68, 39, 50-51; Vol. II, pp. 123, 233-234.
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an unfairly neglected figure — Thomas Laycock.70 Just before Spencer worked out his theories on the basis of evolution, Laycock (who also had heavy debts to phrenology) applied the principle of continuity to all of the nervous system (including the cortex) on the basis of the older philosophy of biology, the great chain of being.71 Jackson's intellectual mentors provided him with the best of the old and the new versions of the principle of continuity as applied to the nervous system.
Four aspects of Jackson's thinking are important in this context. First, on the basis of the views of Spencer and Laycock, Jackson held that the interpretation of the central nervous system in terms of sensation and motion (which began with the Bell-Magendie law) had to extend throughout the nervous system. As he put it in 1870, "If the doctrine of evolution be true, all nervous centres must be of a sensori-motor constitution."72 Since the highest centers have the same composition as the lower, being made up of cells and fibres, "It would be marvellous if, at a certain level, whether we call it one of evolution or not, there were a sudden change to centres of a different kind of constitution. Is it not enough difference that the highest centres of the nervous system are greatly more complicated than the lower?"73 Second, Jackson adopted Spencer's concept of cerebral localization — the only specific feature which Spencer retained from his earlier phrenological period.74 Centers of co-ordination for complex sensations and motions were localized in place of Gall's faculties. Complex mental phenomena were thus reduced to aggregates of sensations and motions paralleled by sets of fibres and cells.75 Third, Jackson explicitly applied this view to the cerebral cortex as a motor organ and argued against those who "think the cerebrum to be likened to an instrumentalist, and the motor centres to an instrument; one part . . . for ideas, and the other for movements."76 Even though some of his writings before 1870 are equivocal about the role of the cortex in movements,77 he did put the issue more clearly than anyone else and ridiculed those who "speak as if at some place in the higher parts of the nervous system we abruptly cease to have to do with impressions and movements, and begin all at once to have to do with mental states"78 — the view that "physical states in lower centres fine away into psychical states in higher centres."79
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70 Ibid., Vol. 1, pp. ix, 37, 123, 167.
71 Thomas Laycock, ~Treatise on the Nervous Diseases of Women (London: Longmans, 1840); "On the Reflex Functions of the Brain," Brit. For. Med. Rev., 1845, 19: 298-311; "Phrenology," in The Encyclopaedia Britannica (8th ed., Edinburgh: Black, 1859), Vol. XVII, pp. 560-561; James Crichton Browne, The Doctor Remembers (London: Duckworth, 1938), pp. 40-41; Young, "Scholarship," pp. 25-26.
72 Jackson, Selected Writings, Vol. II, p. 63.
73 Ibid.
74 Ibid., pp. 216, 234.
75 Herbert Spencer, The Principles of Psychology (London: Longmans, 1855), pp. 606 611.
76 Jackson, Selected Writings, Vol. I, p. 26n. After Jackson's ideas had received experimental support, he never tired of quoting this note in his later papers, e.g., ibid., pp. 42, 58; Vol. II, pp. 63-64, 67.
77 In fact, a close study of his writings before 1870 — when his view was demonstrated experimentally — shows that he was less emphatic than has sometimes been supposed in applying the hypothesis that the cortex was a motor organ: the corpus striatum held his loyalties as the primary motor organ in spite of striking evidence implicating the cortex in disorders of movement. Ibid., Vol. I, pp. 27, 38; Vol. II, pp. 121, 122-123, 127, 216, 233, 239, 240-241, 244. In 1868 he reported a case of "corpus striatum Epilepsy" which involved a post-mortem finding of blood, the bulk of which "lay in one spot over the frontal convolutions, and was so placed as I imagined, to squeeze the corpus striatum...." The discussion refers all symptoms to the corpus striatum and does not mention the convolutions (ibid., Vol. II, p. 218; cf. Vol. 1, p. 9).
78 Ibid., Vol. I, p. 48.
79 Ibid., Vol. II, p. 156.
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This point was linked closely in Jackson's mind with a fourth — philosophical — issue. While his predecessors had indulged in two sorts of interactionism between the unitary mind and the unitary cortex on the one hand and between the mind and its sensory-motor instruments on the other, Jackson (again drawing heavily on Spencer) argued that a clear-cut dualism should be maintained without interaction and that one should postulate a doctrine of concomitance or psychophysical parallelism. The nervous system was to be uniformly sensory-motor, and its physiological processes were paralleled by ideas of sensation and movement.80 This assumption — in the hands of Freud (who adopted it from Jackson)81 and of the majority of later psychologists — continued to be used as a justification for ontological agnosticism about body and mind, while they and the physiologists pursued separate studies, seeking only occasional specification of what is happening in the world of matter and motion when something else occurs in the world of mind. Expressions of dualism could no longer find a convenient demarcation within the nervous system. The "organ of mind" could not be held to be physically as well as functionally discontinuous from the rest of the neuraxis. The fundamental separation of mind from body could still be expressed in the form of psychophysical parallelism, but there was continuity of structure, function, and analytic units within the nervous system itself.
Meanwhile, there were two findings which led the sensory-motor school to consider cerebral localization with renewed seriousness. (The term findings is used advisedly, since the interpretations put on them were vehemently rejected by Jackson and Ferrier.)
Paul Broca provided the first convincing evidence for cerebral localization in 1861. His work was an application of Gall's localizations. Indeed, the faculty of articulate language had been Gall's first discovery (the large flaring eyes which, Gall said, "gave the first impulse to my researches, and was the occasion of all my discoveries").82 However, Broca also insisted on precise study of the brain itself rather than reliance on the measurement of cranial protuberances.83 Broca also argued that speech was an intellectual faculty, not a motor function.84 As he said in a significant aside, "Everyone knows that the cerebral convolutions are not motor organs."85 Even though his first case showed partial paralysis, Broca referred this symptom to the corpus striatum, though the patient's speech defect was localized in the third frontal convolution of the cortex.86
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80 Ibid., Vol. I, pp. 49, 52, 52 n., 55; Vol. II, pp. 84-86, 156.
81 Sigmund Freud, On Aphasia. A Critical Study (1891), trans. E. Stengel (New York: International Universities Press, 1953), pp. 54-56. This position was held consistently throughout Freud's writings, up to and including his last book, An Outline of Psychoanalysis (1940), trans. J. Strachey (New York: Norton, 1949), pp. 13, 34. See also E. Stengel, "A Re-evaluation of Freud's Book On Aphasia: Its Significance for Psycho-analysis," International Journal of Psycho-analysis, 1954, 38: 85-89; Walther Riese, "Freudian Concepts of Brain Function and Brain Disease," Journal of Nervous and Mental Disease, 1958, 127: 287-307.
82 Gall, On the Functions of the Brain, Vol. V, p. 8. The best treatment of the history of research on aphasia in the l9th century remains Henry Head, Aphasia and Kindred Disorders of Speech, 2 vols. (Cambridge: Cambridge Univ. Press, 1926), Vol. I, Chs. 1-5.
83 Paul Broca, "Remarks on the Seat of the Faculty of Articulate Language" (1861), trans. Gerhard von Bonin, Some Papers on the Cerebral Cortex (Springfield: Thomas 1960), pp. 58-59, 72.
84 Ibid., pp. 54, 57
85 Ibid., p. 70.
86 Ibid. Broca's researches on the seat of the faculty of articulate language once again roused the Cartesians, who maintained that the brain must act as a whole. The positions in this debate were paralleled by political views: the conservatives were Cartesians, while the younger liberals and republicans favored cerebral localization. The debate was acrimonious and prolonged in Parisian medical circles. See Head, Aphasia, Vol. I, p. 25.
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Nine years later two young German physicians, Gustav Fritsch and Eduard Hitzig, published a paper entitled "On the Electrical Excitability of the Cerebrum," which demonstrated by experiment that electrical stimulation of discrete cortical areas produced combined muscular contractions.87 Until this epoch-making result, no new experiments fundamentally affecting the role which the cortex was supposed to play in movement had been conducted for almost fifty years. Thus, it is appropriate that Fritsch and Hitzig address their remarks directly to Flourens.88 In the intervening period the sensory-motor paradigm had been applied to progressively higher structures in the nervous system, until a point had been reached just below the cortex (thalamus and corpus striatum). This analysis was not extended by further experiments for twenty-five years. Fritsch and Hitzig eliminated this hiatus. They established cortical excitability, a role for the cortex in the mechanism of movements, and the doctrine of cerebral localization. From their experiments on dogs, five centers were specified at constant foci: for the muscles of the neck, for the extensors and adductors of the anterior leg, (behind that) for the flexion and rotation of the same leg, for the posterior leg, and for the facial nerve.89 Fritsch and Hitzig stress an important reason for the delay in discovering the electrical excitability of the cerebral cortex. The assumption of cerebral equipotentiality had allowed experimenters to refrain from examining and stimulating every part separately.90 Thus, Flourens' belief in Cartesian dualism and the indivisibility of the mind appears to have made it easy for him to refrain from the sort of systematic, localized ablations which would have confirmed cerebral localization. Fritsch and Hitzig were also Cartesian dualists and wrote in interactionist terms about the soul and its material instruments. Their results supported cerebral localization of motor functions, but they argued that their findings left room for other (nonmotor) parts of the cortex as the organ of mind. They felt that psychological functions might also be localized.91 Their views should be contrasted with those of the sensory-motor school in two respects: (1) their interactionism and (2) their distinction between psychological functions and sensory-motor functions.
The examples of Flourens and of Fritsch and Hitzig indicate that philosophical assumptions can, and do, strongly influence the conduct of research and the interpretation of results, even though no empirical finding can falsify a philosophical belief. The relations between philosophical assumptions and scientific research form one of the most interesting aspects of the study of the history and philosophy of science, but it is important to appreciate that these interactions do not occur as formal deductions: the relationships are more subtle and idiosyncratic.
Where Fritsch and Hitzig had found five motor centers, an Englishman, David Ferrier, soon found fifteen and went on to specify areas for each of the five senses.92 Ferrier began his experiments as an attempt to confirm Jackson's clinical findings by reproducing seizures by means of electrical stimulation of the cortex.93 He also
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87 Von Bonin, Some Papers, pp. 81, 96.
88 Ibid., pp. 75-78.
89 Ibid., pp. 83-84.
90 Ibid., p. 90.
91 Ibid., pp. 77, 92, 96.
92 David Ferrier, "Experimental Researches in Cerebral Physiology and Pathology," West Riding Lunatic Asylum Medical Reports, 1873, 3: 30-96; The Functions of the Brain (London: Smith, Elder, 1876), pp. 163-196; 2nd ed. (1886), pp. 268-345. [I visited this mental hospital in August 1996. It was, like most of the old custodial asylums, closed, but on the map of the site, one ward was named ‘Ferrier’.]
93 Ferrier, "Experimental Researches," pp. 30, 85-87; The Localization of Cerebral Disease (London: Smith, Elder, 1878), p. 14.
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set out to confirm and extend the work of Fritsch and Hitzig.94 The significance and continuity of influences can be seen from the fact that the monograph which summarized and interpreted his findings was dedicated by Ferrier to Jackson.95 In fact, he is as lavishly deferential toward Jackson as Jackson was toward Spencer.96 Sherrington, in turn, dedicated his classical lectures on The Integrative Action of the Nervous System (1906) to Ferrier.97 In his obituary notice of Ferrier for the Royal Society Sherrington pointed out that Ferrier had done the most important research in proving cerebral localization, in placing it at the center of neurological interest, and in providing the basis for a "scientific phrenology."98
The significance of Ferrier's work was quickly appreciated. Accounts from the British Association, the President's Address to the Royal Society, and the 1901 supplement to the Encyclopaedia Britannica, as well as contemporary reviews of his works, all confirm that it made as much a stir as the Bell-Magendie law had fifty years earlier.99 Even Carpenter was moved to rank Ferrier's localizations among the greatest advances in the physiology of the nervous system which had been made in the last fifty years, and he acknowledged the existence of the missing fibres connecting the cortex and lower centers, although he held fast to his former separation of the cortex and its functions from the sensory-motor paradigm — the hiatus which was undermined in the very report which he was praising so lavishly. He saw no inconsistency between his former views and Ferrier's findings.100
Ferrier referred to the psychological interpretation of his findings as "scientific phrenology." He reasoned as follows. His first experiment was on a guinea pig which died before its responsiveness to electrical stimulation could be determined. His next experiments were on rabbits and cats. Electrical stimulation produced more or less localized convulsions (thus confirming Jackson) but no discrete movements.101 It was in his fourth experiment (on a cat) that Ferrier obtained localized, discrete movements. For example, in one place stimulation produced slow
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94 Ferrier, "Experimental Researches," p. 30.
95 "To Dr Hughlings Jackson who from a clinical and pathological standpoint anticipated many of the more important results of recent experimental investigation into the functions of the cerebral hemispheres, this work is dedicated as a mark of the author's esteem and admiration." Ferrier, The Functions of the Brain (1876), p. v.
96 David Ferrier, "The Localisation of Function in the Brain" (MS). Communicated by J. B. Sanderson 5 March 1874. Archives of the Royal Society AP.56.2. (Abstract in Proceedings of the Royal Society, 1874, 22: 229-232), MS, p. 129V; cf. Ferrier, The Functions of the Brain (1876), pp. 256-257; Localization, p. 14.
97 Charles S. Sherrington (New York: Scribner's, 1906), p. v: "In token recognition of his many services to the experimental physiology of the nervous system."
98 Charles S. Sherrington, "Sir David Ferrier, 1843-1928 " Proc. Roy. Soc., 1928, 103B: viii-xvi, pp, x, xiii.
99 William Rutherford, "Address to the Department of Anatomy and Physiology," Report of the Forty-Third Meeting of the British Association for the Advancement of Science (London: Murray, 1874), Transactions, pp. 119-123, p. 122; George B. Airy, "President's Address," Proc. Roy. Soc., 1873 1874, 22: 2-12, p. 9; Anon. (C. S. Sherrington), "Phrenology," in The New Volumes of the Encyclopaedia Britannica (10th ed., Edinburgh: Black, 1902), Vol. XXXI, p. 710 George C. Robertson, "Critical Notice of 'The Functions of the Brain', by David Ferrier," Mind, 1877, 2: 92-98, p. 92. For an accurate dramatization of the significance of Ferrier's findings, see Jürgen Thorwald, The Triumph of Surgery, trans. R. and C. Winston (London: Thames & Hudson, 1960), Ch. 1. The medical applications of Ferrier's findings in localizing neurosurgery deserve further historical study.
100 William Carpenter, "On the Physiological Import of Dr. Ferrier's Experimental Investigations into the Functions of the Brain," West Riding Lunatic Asylum Med. Reps., 1874, 4: 1-23, pp. 2, 7-8, 18-19; Mental Physiology, pp. 709, 715, 719.
101 Ferrier, "Experimental Researches," pp. 34 38.
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flexion of the phalanges of the left forepaw and elevation of the left shoulder; in another place it produced signs of pain, screams, and kicking with both hindlegs, especially the left.l02 Thus, he found that motion and signs of sensation resulted from stimulation of the cortex. However, he soon extended his interpretations. In a later experiment (on a dog) stimulation produced behavior interpreted as dream like on general observation, including wagging of the tail and spasmodic twitching of the right ear.l03 Ferrier received a grant from the Royal Society which allowed him to extend his researches to monkeys. He identified centers for advance of the opposite hind limb, as in walking; and retraction, with adduction of the opposite arm, as in swimming.104 By 1874 he was convinced that he was investigating not merely artefacts and induced contractions, but the basis of voluntary movements.l05 Thus, his inferences moved from contraction to purposive movement to biological functions. This reasoning led him to claim that he could "artificially excite conditions similar to normal psychic or volitional stimuli" and to "translate into their psychological signification and localize phrenologically the organic centers for various mental endowments.''106
The resulting conception of the functions of the brain is a corollary of the theories of Bain, Spencer, and Jackson, for which Ferrier felt that he provided the experimental evidence: ". . . it must follow from the experimental data that mental operations in the last analysis must be merely the subjective side of sensory and motor substrata" — a view which he attributes to Jackson.l07 He adds in the second edition, "For the cerebral hemispheres consist only of centers related respectively to the sensory and motor tracts, which connect them with the periphery and with each other.''l08 Ideas are revived associations of sensations and movements, thought is internal speech, and intellectual attention is ideal vision.l09 The centers for special sensory and motor activities "in their respective cohesions, actions, and interactions form the substrata of mental operations in all their aspects and all their range.''110 In short, all conceptions of function are reducible to sensation, motion, and association. Ferrier's work represents the final extension of the Bell-Magendie paradigm to the most rostral part of the neuraxis — the cerebral cortex — and its use as an all-embracing explanatory conception in both physiology and psychology.
When Gall finished his work On the Functions of the Brain in 1825, he re marked that he would have liked to withhold it longer but that death was imminent, "and I must be content with leaving this first effort in the physiology of the brain, far less perfect than it will be fifty years hence.''111 In 1876 Ferrier's monograph, with the same title, appeared. In comparing them, one finds the balance between physiological and psychological statements reversed. Gall's work was almost wholly devoted to the discovery and exposition of the faculties or functions. Ferrier devotes only ten per cent of his text to what he calls "the subjective aspect of the functions of the brain." Most of his book is devoted to the "physiological aspects," and he concluded that these consist of "a system of sensory and motor centers. In their subjective aspect the functions of the brain are synonymous with mental operations, the consideration of which belongs to the science of psychology." All that
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102 Ibid., pp. 41-42.
103 Ibid., p. 51.
104 Ferrier, The Functions of the Brain (1876), pp. 141-142.
105 Ferrier, "Localisation" (MS), pp. 95 97, 117-118.
106 Ferrier, "Experimental Researches," pp. 72, 76.
107 Ferrier, The Functions of the Brain
(1876), pp. 256-257.
108 Ibid. (1886), p. 426
109 Ibid., pp. 437, 462, 463-464.
110 Ibid., p. 467.
111 Gall, On the Functions of the Brain Vol. VI, p. 293.
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Ferrier felt was needed to convert his physiological findings into psychologically significant statements was the assumption of psychophysical parallelism and the phrase "subjective aspect.''112
If Gall was naive in believing that the organization and physiology of the brain corresponded with his faculties in a one-to-one fashion, Ferrier was equally so in suggesting that the primary sensory and motor areas could explain psychological functions in a simple manner. He had localized sensory and motor areas, but he had not provided a psychophysiology which accounts for the adaptations of organisms to their environments. As a recent commentator put it, "Whatever its role in the production of muscular activity, the motor cortex cannot be regarded as the seat of any function recognisable to the student of behaviour.''113
Experimental sensory-motor physiology was on a firm experimental basis, built up by progressive extension of the Bell-Magendie law — a certain fact about the nervous system — and then united with the concept of cerebral localization. However, cerebral localization had become scientific only by abandoning the goals which Gall had laid down at the beginning of his research: to relate the significant variables in the character and behavior of men and animals to the functioning of the brain. The sensory-motor school was undoubtedly right in rejecting Gall's faculty psychology. However, in being grounded on a secure physiological basis, the sensory-motor tradition cut itself off from the approach to psychology which was the most important aspect of Gall's work and which had been extended by Spencer's conception of psychology as a biological science. In rejecting Gall's answers, it lost sight of the significance of his questions. Insufficient attention was paid to what the sensory-motor elements should be required to explain. In default of significant questions, the only answers that were forthcoming were about sensory modalities and muscular movements and led only to a partial understanding of the primary projection areas of the somatic cortex. The role of many of these in normal behavior has yet to be determined. Questions about adaptive, biologically significant functions had to be asked anew by other branches of biology which developed independently on the basis of other aspects of the ideas of Bain, Spencer, and Darwin. The problem which Ferrier bequeathed to the present century was that of retaining scientific rigor while regaining contact with biologically significant functions.
Gall and Ferrier can be seen as extremes on a continuum of possible approaches in brain and behavior research. Gall stressed functions as adaptive and related them to character, mastery of the environment, and social and intellectual achievements. He allowed his catalogue of functions to dictate how the brain must be organized and made no significant findings in neurophysiology. Ferrier, on the other hand, sacrificed the significance of functions to physiological accuracy. As John Dewey said in 1900, "Unless our laboratory results are to give us artificialities mere scientific curiosities, they must be subjected to interpretation by gradual re-approximation to the conditions of life.''114 That is, mediation between the extremes required integration of the independent findings of physiologists, psychologists, and students of animal behavior (ethologists). Though Gall was unable to follow his own advice, latter-day behavioral scientists are in a better position to do so. He said, "Whoever would not remain in complete ignorance of the resources which
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112 Ferrier, The Functions of the Brain (1876), pp. 255-257.
113 O. L. Zangwill, "The Cerebral Localisation of Psychological Functions," Advancement of Science 1963-1964 20: 335-344 p 337
114 John Dewey, "Psychology and Social Practice," Psych. Rev., 1900, 7: 105-124, p. 119.
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cause him to act . . ., should know, that it is indispensable, that the study of the organization of the brain should march side by side with that of its functions.''115
Before concluding, one might recall Gall's influence and suggest that there is still more to be learned from him. As G. H. Lewes said, "Gall rescued the problem of mental functions from Metaphysics and made it one of Biology.''116 "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.''117 His influence on Bain and Spencer was most significant, and lesser figures such as Laycock and Carpenter also derived much from Gall's approach. However, neither they nor their modern heirs — the behaviorists — have transcended the categories which Gall opposed in the name of biology. The functional psychology of William James and John Dewey advocated the study of mental functions as adaptations, but they also failed to provide new and significant categories.
In 1940, Sherrington pointed out that the new phrenology was as far as the old had been from understanding the role of the nervous system in integrated behavior and that there were not even names for the categories which are ultimately needed.118 Modern brain and behavior research is still attempting to find ways of asking and answering the question, What are the functions of the brain? It appears that the answers to this question will, in the first instance, owe more to the field studies of the ethologist than to physiological experiments. It was Gall who made the point that we must first know the functions before we can ask intelligent questions about the organization and physiology of the brain. A century and a half later, one finds a recent reviewer of the concept of cerebral localization turning to Gall in support of the thesis that "in exploring the functions of the brain, I am convinced that we must limit ourselves to the study of biologically significant behavior patterns, no matter how complex their underlying physiology may be.''119 This, it seems to me, is the scientific lesson of the foregoing account.
Turning to the philosophical issues, if anyone believes that the problems set by Descartes no longer plague biological psychology, he should consider the fact that modern research is not dealing only with the two languages of extended substances and thinking substances. Though Descartes might well recognize the activities and concepts of the physiologist, he would be puzzled by the coexistence of the categories of function in the Passions of the Soul and the Treatise on Man (that is, memory, reason, intelligence) with the atomistic units of the association psychology. These last have in turn been made objective in a third language—the stimuli and responses of the behaviorist which, their claims not withstanding, have defied reduction to matter and motion. Thus, we have one language of brain, two of mind, and a fourth of behavior. Add to these the concepts of the evolutionary biologist, and we find five sets of variables.
The problem for the future can be approached by two paths. The first involves transcending these several languages with a new ontology. The second — which is at present in vogue — is to find translation rules among them. Whichever approach is taken, it seems clear that careful historical studies can help to provide the per
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115 Gall, On the Functions of the Brain, Vol. II, pp. 45-46
116 George H. Lewes, The History of Philosophy from Thales to Comte, 2 vols. (3rd .ed. London: Longmans, 1867-1871), Vol. II, p. 425
117 Ibid., p. 423.
118 C, S. Sherrington, Man on His Nature (Cambridge: Cambridge Univ. Press, 1940), p. 228
119 Zangwill, "Cerebral Localisation," p. 338.
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spective on the current confusion which is necessary for increased communication among the physiologist, the layman, the behaviorist, and the ethologist. As a final remark, one might suggest that no set of translation rules will transcend the problems which Descartes has bequeathed to us. The best that can be hoped for from compiling a dictionary of translation rules is better communication, not a coherent ontology for interpreting nature—including human nature.
This article first appeared in Isis Vol. 59, Part 3, No. 198, 1968, pp. 251-68. It is a summary, stressing philosophical implications, of the argument of my Mind, Brain and Adaptation in the Nineteenth Century: Cerebral Localization and Its Biological Context from Gall to Ferrier (Oxford: Clarendon Press, 1970; reprinted N. Y.: Oxford Univ. Press, 1990).
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