P. M. S. Hacker - Philosophical Foundations of Neuroscience

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

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 his lecture on consciousness in 1965, Adrian observed that, in general, natural scientists prefer to remain uncommitted on such questions as the relationship between mind and matter. However, he admitted, it is difficult for physiologists to maintain such Olympian detachment. Any neuroscientist concerned with studying the sense-organs and the central nervous system can hardly avoid the problems that have always arisen in trying to relate physical events and activities in the body to mental activities. The problem can be put most starkly by reflecting on the fact that one might, according to Adrian, build a mechanical human being that behaved exactly as we do. For the ‘universal Turing machine’, he observed wittily, can ‘turn its band to any problem’, and a ‘man-machine’ might be programmed to do anything we can do. What would be missing, however, ‘is ourself, our ego, the I who does the perceiving and the thinking and acting, the person who is conscious and aware of his identity and his surroundings’. 9We are convinced, Adrian remarked, that we have an immediate awareness of ourselves, and that this is one thing that a machine could not copy.

Adrian’s hesitant Cartesianism

This thought is, to be sure, Cartesian through and through. What differentiates man from mechanical animate nature is, according to Descartes, consciousness. Descartes assimilated consciousness to self-consciousness in one sense of the latter term. For he held that thought, which is the essential attribute of mind, is defined as ‘everything which we are aware of as happening within us, in so far as we have an awareness of it’. Notoriously, Descartes held that the foundation of all knowledge was each person’s consciousness of his own thoughts, and hence his indubitable knowledge of his own existence. In this respect, Adrian followed Descartes. For, he observed,

I used to regard the gulf between mind and matter as an innate belief. I am quite ready now to admit that I may have acquired it at school or later. But I find it more difficult to regard my ego as having such a second-hand basis. I am much more certain that I exist than that mind and matter are different.