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The work of John Hughlings Jackson (1835-1911) has attracted considerable attention among historians and philosophers of science because it set a conceptual framework for scientific neurology. In this paper we examine the notion, espoused by some modern writers, that his scientific work was motivated by a deep interest in metaphysics. There are two elements in the story—a youthful crisis of intention, and an alleged mature interest in formal metaphysical speculation. We use the term metaphysics to describe the extrapolation of a scientific theory beyond the phenomena it is intended to explain1. For example, Herbert Spencer's extension of evolutionary principles beyond biology into all manner of social and political realms is a form of metaphysical speculation. On this view of metaphysics, we argue, Hughlings Jackson's personal intentions were not at all metaphysical.
John Hughlings Jackson was born on 4 April 1835 in the village of Green Hammerton, 10 miles northwest of York. He was the youngest of five children. His father, Samuel Jackson, was a prosperous brewer and farmer. His mother, the former Sarah Hughlings, died when he was a year old. He was educated in a series of provincial schools. At age 15 he ended his formal education and became an apprentice to William Charles Anderson, a prominent physician in York. After two years of working in Anderson's household, Hughlings Jackson began classes at the York Medical School, whose faculty lectured, for a fee, to the dozen or so students in attendance. Here he was a student of Thomas Laycock, later professor of medicine in Edinburgh, who exerted a strong influence on his medical and physiological interests2,3,4. In 1855 and 1856 he walked the wards at St Bartholomew's Hospital in London, where he attracted the attention of James Paget5.
Also in 1856, he became a Licentiate of the Worshipful Society of Apothecaries, a Member of the Royal College of Surgeons and a Licentiate of the Royal College of Physicians. After qualifying, he was appointed resident medical officer at the City Dispensary in York, where he spent the next three years. At some time between May and October 1859 Hughlings Jackson left York and moved to London. There he met and formed a lifelong friendship with his fellow Yorkshireman Jonathan Hutchinson, who had followed a similar educational path6,7,8.
The story of Hughlings Jackson's youthful crisis of intention is found only in Hutchinson's 1911 British Medical Journal obituary, written fifty years after the events described6. Hutchinson's entire description of this episode, published a week after his friend's death, is as follows:
‘When Dr. Jackson and myself first made acquaintance he had been some two or three years in the profession, and, in the belief that it did not afford attractive scope for mental powers of which he was not unconscious, he was on the point of abandoning it, intending to engage in a literary life. From this I was successful in dissuading him, and for many years I plumed myself upon this as the most successful achievement of my long life. Of late, however, I have had my misgivings, and have doubted whether—great as had been the gain to medicine—it might not have been a yet greater gain to the world at large if Hughlings Jackson had been left to devote his mind to philosophy. There are others who are better skilled than myself to give an opinion on this head, but at some future time I may hope to be able to produce some details in illustration of his character which may go far to justify my misgivings’6.
Eight weeks later Hutchinson wrote a longer memoir, but did not expand on Hughlings Jackson's literary or philosophical ambitions9.
The young Hughlings Jackson was undoubtedly ambitious, but the nature and direction of his ambition must be viewed in context. His background did not qualify him for an academic career, philosophical or otherwise. His general education had ceased at age fifteen, before any secondary or university schooling. He came from yeoman stock, and his family were religious dissenters4. Therefore, he had very little chance of gaining admission to what might be called a philosophy school or graduate programme, much less being appointed to an academic position in philosophy.
Socioeconomic analysis reveals a more plausible explanation of this episode. Hughlings Jackson's grandfather had bought Providence Green, a brewhouse and farm, which was probably a good business in rural nineteenth century Yorkshire. Hughlings Jackson's father Samuel had inherited Providence Green and raised a family of a daughter and four sons there. However, Samuel Jackson lost a lot of money late in life, possibly in railway stock speculation. The precise timing of Samuel's financial troubles is not clear, but in a letter dated 17 March 1854 he exhorted his son John to a life of frugality in dress and custom4.
Hughlings Jackson's eldest brother, also named Samuel, received enough education to study law in the city of York. His three brothers, including Samuel, emigrated to New Zealand after 1856, at the time their father moved out of Providence Green and into a house in Green Hammerton. Hughlings Jackson was then a resident medical officer in York. He might have received some compensation as a houseman, but he probably received little support from his family. His father was by now impoverished and in failing health, and this may have been the reason for Hughling Jackson's return to Yorkshire from London in 1856. It must have been a threadbare existence4.
Samuel Jackson died on 9 February 1858 while his son John Hughlings Jackson was in his second year as a houseman in York4. Eighteen months later the son moved to London permanently, burning with ambition and well aware of his own intellectual powers9. It was at this time that he had his crisis of intention. At age 24, with little money, he no doubt sought to use his intellect to make a living, and he probably regarded medicine as only one of several options. For example, he must have known something of the law, since his brother was a lawyer. He also read voraciously, most notably Carlyle and Dickens. In thinking how a self-aware, medically sophisticated intellectual might support himself in 1859 London, Hughlings Jackson must have considered some kind of writing for money. Hutchinson would have interpreted this as a ‘literary life’. Probably, either non-fiction or journalism is what he had in mind. It seems far-fetched to imagine the ambitious young Hughlings Jackson taking rooms in a university to study philosophy, even had he the background to do so.
Furthermore, grand scientific syntheses were becoming a social and publishing phenomenon in mid-Victorian Britain. The success of Robert Chambers's Vestiges of the Natural History of Creation, first published in 1844, emboldened both Darwin and Spencer to publish their own synthetic works10. These volumes had wide appeal among the increasingly literate and prosperous public. None of the writers were academic scientists, though they might be called literary scientists or even literary philosophers. An ambition to write treatises of synthetic science, rather than to pursue a career in academic philosophy, seems a better explanation of Hughlings Jackson's goal of a ‘literary life’.
In fact, Hughlings Jackson did write a book of synthetic science entitled Suggestions for Studying Diseases of the Nervous System on Professor Owen's Vertebral Theory, which he published for private circulation in early 186311. In this work he elaborated Richard Owen's theory that the skull develops from four embryological vertebrae, each of which innervates specific viscera. Each vertebro-visceral system has its own blood supply, sensory network and musculature. Hughlings Jackson supplied both the normal and the pathological anatomy of these systems, and suggested that each system had a distinct form of epilepsy. In the preface of this pamphlet he discounted the usefulness of this synthesis. Nevertheless, he continued to search for unifying neurophysiological principles11.
Despite a busy clinical life Hughlings Jackson was a prolific writer. Assessing any writer's motivation is a difficult task, a task made doubly difficult in Hughlings Jackson's case because he had his executor burn all his personal papers after his death8. Very little autograph material remains other than his published works, but he did leave several published comments about his creative motivation. These show him to be a practical physician whose primary motivation was medical science rather than theory or philosophy. Moreover, he published exclusively in medical journals, lectured mainly to medical audiences and spent his days practising medicine. Therefore he could expect to have his work seen and criticized by his fellow physicians but not necessarily by academic scientists or academic philosophers.
Hughlings Jackson specifically rejected metaphysics and materialism, two areas of Victorian philosophical enquiry. In a preface to his 1875 pamphlet on cerebral localization, he said that it is possible to practise medicine with any metaphysical beliefs or none at all. He said, ‘That along with excitations or discharges of nervous arrangements in the cerebrum, mental states occur, I, of course, admit; but how this is I do not inquire; indeed, so far as clinical medicine is concerned, I do not care’12. The next year, in a paper on Todd's paralysis, he wrote that the aim of his mechanical view of the nervous system was to combat metaphysical neurophysiology. He discounted the philosophical idea that there exists a centre of the nervous system that acts as a metaphysical interpreter, standing outside of sensory and motor function13.
In an address to the Section of Pathology at the August 1882 meeting of the British Medical Association in Worcester, Hughlings Jackson criticized metaphysical explanations of disease. He stated, ‘... it is rather difficult to define metaphysics. Some people call psychology metaphysics; some call anything very difficult and complex about mind and body metaphysics; some use it merely as a term of abuse’14. As an example of metaphysical explanations of disease he used the proposition that aphasic patients have lost words but not the memory of words. He said that, on the contrary, the words we speak and the words we think are the same thing; if not, mental words would be insubstantial. According to the law of conservation of energy, insubstantial phenomena cannot produce speech in any manner. He also lamented that medical students are not taught metaphysics, so they could be less metaphysical in their professional life. Declaring that metaphysical explanations of hysteria explain nothing, he asserted that scientific physicians must steer clear of metaphysics14.
Hughlings Jackson took a dim view of materialism. He devoted his third Croonian Lecture of 1884 to the relationship of the brain to the mind15. In this lecture he specifically disclaimed materialism, citing as sources a litany of scientists and writers including William Hamilton, John Stuart Mill, Herbert Spencer, Freidrich Max Müller, Alexander Bain, Thomas Henry Huxley, Emil DuBois-Reymond, Thomas Laycock, John Tyndall and David Ferrier15. This group, which Hughlings Jackson identified as a scientific peer group, includes physicians and philosophers, professors and writers, and one or two figures who defy categorization. He again claimed a medical rather than a philosophical motivation and first enunciated his Doctrine of Concomitance, which asserts that the nervous system is an explicitly sensorimotor machine arranged as an evolutionary hierarchy. According to the doctrine of concomitance, the nervous system and the mind are two completely separate entities, and neither causes the other to act in any way.
In April 1887 Hughlings Jackson published his remarks on the evolution and dissolution of the nervous system in the Journal of Mental Science16. In this paper he says that a critic of his Croonian Lectures had accused him of fabricating the doctrine of concomitance in order to avoid the charge of materialism, and of appropriating Leibniz's ‘two-clock theory’. He replied that this might be true but it does not matter, because Leibniz's philosophy is irrelevant to medicine. He added that evolutionists need not invoke supernatural agency to explain natural phenomena. He claimed that it is impossible to localize mental function because the nervous system is exclusively sensorimotor. Reiterating his discussion of mind—body theories he said that he could accept a mind—body identity theory if it meant that the nervous system has two functions, integration and thinking. Even if the mind—brain identity theory was right, the doctrine of concomitance as an artifice was still useful for physicians because it separated practical bedside diagnosis from non-localized psychological function16. According to Hughlings Jackson, mental disease may be present but its nature excludes it from the purview of medical science.
In developing a practical form of bedside neurology, Hughlings Jackson was forced to distinguish between neurological and mental functions. The doctrine of concomitance was one solution to the mind—body problem, now called psychophysical parallelism—the theory that brain and mind exist in parallel but are causally unrelated, like two clocks running in tandem. He recognized other possible solutions; however, he found that parallelism enabled the development of practical scientific neurology because it allows the neurologist to ignore mental function completely16. It is the continuing usefulness of Jacksonian concomitance that has generated so much speculation about the role of metaphysical intention in his thinking, though commentators use the term philosophy rather than metaphysics.
Hughlings Jackson's first biographer, his student and collaborator James Taylor, wrote a biographical introduction to his Selected Writings of John Hughlings Jackson. Taylor wrote, ‘There were always the two sides to his teaching, the clinical and the philosophical, but these two sides are in such intimate combination that there is no corresponding division of his papers which would enable one to devote a volume to each’8. He quotes Hutchinson as saying that the young Hughlings Jackson intended to devote himself to philosophy. He characterizes Hughlings Jackson's writings on evolution of the nervous system as his most philosophical work. Hughlings Jackson's modern biographers, Macdonald and Eileen Critchley, reiterate these views and add that he expressed an interest in academic philosophy2.
Several historians of medicine have commented on Hughlings Jackson's philosophical intentions. Temkin, in his history of epilepsy, takes note of Hughlings Jackson's youthful crisis, saying that he intended to pursue a literary life, but is neutral on Hughlings Jackson's metaphysical motivation either in youth or in mature life19. Similarly Greenblatt, in his seminal study of the early influences on Hughlings Jackson's life and work, likewise interprets Hughlings Jackson's early crisis as one of literary rather than metaphysical intent6. By contrast Lennox, in his article on Hughlings Jackson in a compendium of brief biographies, says that as a young physician Hughlings Jackson was inspired by Herbert Spencer's work to abandon medicine in favour of the study of philosophy20. Clarke says that Hughlings Jackson conceived his interest in philosophy while a houseman in York, and that Hutchinson dissuaded him upon his arrival in London21. Gross, in his narrative history of the neurosciences from Imhotep to Hubel and Weisel, says, ‘As a medical student Hughlings Jackson was so enthralled with Spencer's writings that he almost abandoned medicine to study them full time’22. Young quotes Taylor's remark that Hughlings Jackson ‘had fully resolved to give up medicine and devote himself to philosophy’23. Harrington mentions the episode in passing, repeating the assertion that Hughlings Jackson intended to study philosophy24.
In our opinion there is scant evidence for claims that Hughlings Jackson was driven by metaphysical concepts. He even claimed that the metaphysical import of his work, if any, was irrelevant to his purpose12. This pragmatic attitude is consistent with what we know of Hughlings Jackson's personality. His friend Thomas Buzzard wrote that Hughlings Jackson had an appealing Yorkshire manner, at the same time open-minded and sturdily disinclined to change his mind once convinced of a point25. Though Buzzard does not call his friend a hardheaded Yorkshireman, his description comes close to it.
In addition, Hughlings Jackson was not a lonely recluse, as has been claimed26. Every day for over thirty years he was driven by carriage from his house in Marylebone to the National Hospital in Bloomsbury and to the London Hospital in Whitechapel. He took Buzzard's children to the London Zoo, the aquarium and a bookstore in Covent Garden27. His junior doctors accompanied him on house calls. These trips took him through the bustling centre of the City, which he observed minutely28. He loved London, and was a regular figure at medical meetings in the metropolis for over thirty years. He might have been melancholy in disposition, but he participated in the life of the City.
Theoretical scientists such as Hughlings Jackson are often thought to have metaphysical intentions because the abstract and fundamental nature of their work challenges accepted views of the world. From the perspective of a century later, the work of Hughlings Jackson, like that of Einstein, Bohr or Planck29, is genuinely important, and his motivation is strikingly similar to that of other scientific theorists.
This commonalty of opinion among influential scientists, though anecdotal, suggests the possibility of a more general historical principle. Scientists may resent non-rigorous interpretation of their ideas, and express an explicit disdain for metaphysics. Some commentators see a cyclical relationship between scientific theory and metaphysics that scientists themselves find amusing, and occasionally obnoxious30. A new scientific idea is often initially rejected because it conflicts with a dominant philosophical orthodoxy. If the theory proves useful, it may influence society in important ways, in the process becoming part of a new metaphysics. By then, observations accumulate that collectively threaten the new orthodoxy. In this way modern science and philosophy rarely agree and are often completely out of phase—a phenomenon that may lead the scientist to reject metaphysics more vehemently than appears justified.