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nervous system (see §5.1). Similarly, the body has no thinking to do – there is no such thing as one’s body thinking. It is human beings who think, and their thinking is not done for them by their brain – they have to do their own thinking (see §7.2). There is no such thing as the brain’s thinking anything – although, of course, human beings would not be able to think but for the normal functioning of their brain. ( That, to be sure, does not imply that one thinks with one’s brain, in the sense in which one walks with one’s legs or sees with one’s eyes.)

      Sherrington on the mind–brain nexus: misunderstandings of Aristotle

      Given this confused dualism, the question of the relation between the two putative entities cannot but arise. Sherrington asserted that no one doubts that there is, as he put it, ‘a liaison’ between brain and mind. But ‘The “how” of it we must think remains for science as for philosophy a riddle pressing to be read’ (MN 190).

In all those types of organism in which the physical and the psychical coexist, each of the two achieves its aims only by reason of a contact utile between them. And this liaison can rank as the final and supreme integration completing its individual. But the problem of how the liaison is effected remains unsolved; it remains where Aristotle left it more than two thousand years ago. There is, however, one peculiar inconsistency which we may note as marking this and many other psychological theories. They place the soul in the body and attach it to the body without trying in addition to determine the reason why, or the condition of the body under which such attachment is produced. This, however, would seem to be a real question.⁷

It is curious to find Sherrington writing this, since he knew that the question of how the mind can interact with the body is not a question that can arise for Aristotle. Within the framework of Aristotelian thought, as we have seen (§1.1), the very question is as senseless as the question ‘How can the shape of the table interact with the wood of the table?’ Aristotle manifestly did not leave this as a problem within his philosophy. The problem arose within the framework of Plato’s dualist philosophy, which was contested by Aristotle but nevertheless informed Neoplatonism and, via Saint Augustine, came to dominate Christian thought. To be sure, Thomas Aquinas adopted Aristotelian psychology and strove, with questionable coherence, to adapt it to Christian theology. But Platonic dualism remained the most natural conception for popular Christianity, and it informed the Renaissance form of Neoplatonism. The relationship between mind and body is highly problematic for any form of dualism, and with the seventeenth-century dominance of Descartes and the corresponding decline in the influence of Aristotelian philosophy, the problem of interaction came on to the agenda again, and has remained there ever since.

      Sherrington on the irreducibility of the mental

      Sherrington contributed nothing towards its solution. He noted that science was impotent to solve the problem:

      Life … has resolved itself into a complex of material factors; all of it except one factor. There science stopped and stared as at an unexpected residue which remained after its solvent has dissolved the rest. Knowledge looking at its world had painfully and not without some disillusions arrived at two concepts; the one, that of energy, which was adequate to deal with all which was known to knowledge, except mind. But between energy and mind science found no ‘how’ of give and take .… To man’s understanding the world remained obstinately double.(MN 200)

      Life and the processes of life, Sherrington observed, were explicable by physics and chemistry, but ‘thought escapes and remains refractory to natural science. In fact natural science repudiates it as something outside its ken’ (MN 229). This is, of course, untrue. For psychologists can and do study thinking – which is not in any sense ‘outside its ken’. But it is evident that what Sherrington meant was that thinking and thought are not reducible to physics and chemistry. ‘For myself’, he wrote, ‘what little I know of the how of the one [i.e. the brain] does not, speaking personally, even begin to help me toward the how of the other [i.e. the mind]. The two for all I can do remain refractorily apart. They seem to me disparate; not mutually convertible; untranslatable the one into the other’ (MN 247). On the matter of strict reducibility, at any rate, he is quite right (see below, §16.1).

      Sherrington on mind–body interaction

      Sherrington’s conception of the interaction between mind and body was Cartesian (although without the Cartesian commitment to the interactionist role of the pineal gland).

      I would submit that we have to accept the correlation, and to view it as interaction; body ⇒ mind. Macrocosm is a term with perhaps too medieval connotations for use here: replacing it by ‘surround’, then we get surround body mind. The sun’s energy is part of the closed energy cycle. What leverage can it have on mind? Yet through my retina and brain it is able to act on my mind. The theoretically impossible happens. In fine, I assert that it does act on my mind. Conversely my thinking ‘self’ thinks it can bend my arm. Physics tells me that my arm cannot be bent without disturbing the sun. My mind then does not bend my arm. If it does, the theoretically impossible happens. Let me prefer to think the theoretically impossible does happen. Despite the theoretical I take it that my mind does bend my arm and that it disturbs the sun.(MN 248)

      ‘Reversible interaction between the “I” and the body’, he concluded, ‘seems to me an inference validly drawn from evidence’ (MN 250). This is a deep confusion – for it is not ‘the “I”’ that moves my arm when I move my arm; nor indeed is it my mind. I do so – and I am neither my mind, nor am I a ‘self’, an ‘ego’, or ‘an “I”’. I am a human being. And it is not ‘my thinking self’ or my mind that thinks it can bend my arm; rather, I, this human being, think that I can bend my arm, and usually do so when asked.

Sherrington was admirably candid in confessing his bafflement. But he did not realize that the root of the trouble is conceptual confusion – not empirical ignorance. And he was not aware of the revolution in philosophy that was taking place at that very time in Cambridge that would have enabled him to disentangle his confusions. His predicament was not unlike Descartes’s, 300 years earlier. Writing in his old age to Princess Elizabeth of Bohemia, who asked him how a thinking soul could move the animal spirits, the great philosopher and scientist confessed that ‘I may truly say that what your Highness proposes seems to me the question people have most right to ask me in view of my published works.’⁸

      2.2 Edgar Adrian: Hesitant Cartesianism

      Adrian’s achievement

      Edgar Douglas Adrian (1889–1977) was a much younger contemporary of Sherrington, with whom he shared the Nobel Prize in 1932. Adrian’s work is in certain respects complementary to Sherrington’s, for it gives an account of the electrical activity in both motor and sensory nerve fibres that accompany reflex and other integrative actions of the nervous system. Adrian showed that there is only one kind of action potential in nerve fibres, no matter whether these are motor or sensory ones. Furthermore, he showed that the force of contraction and the intensity of sensation are graded as a consequence of different frequencies of action potential firing in the nerves as well as changes in the number of nerve fibres that are firing. He later turned his attention to the origins of electrical oscillations in the brain, and established that the Berger rhythm comes from the occipital part of the cortex.

      His reluctance to speculate

      The question ‘How is the brain related to the mind?’ puzzled Adrian no less than it puzzled others. But, unlike Sherrington, he was disinclined to speculate upon the nature of the mind, or upon the question of how brain activities are related to mental phenomena. His reflections on such questions are therefore relatively few, and expressed with considerable caution. Nevertheless, it is worth surveying them briefly, for they raise questions that still bewilder neuroscientists. Though Adrian did not commit himself to Cartesian dualism, Cartesian elements do creep into his cautious and tentative remarks, as we shall see.

      The ‘man-machine’ and the ego

In

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