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

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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.

      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

      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.

      Moreover, Adrian continued, ‘in the study of the human ego, introspections are almost all we have to guide us’. ‘Introspections’, presumably, reveal to us the sensory, perceptual and emotional contents of consciousness. This (mis)conception conforms with the venerable philosophical tradition that stems from Descartes and the British empiricists. It is a general (mis)conception that is still characteristic of much neuroscientific reflection on these matters, especially among those neuroscientists who think that ‘qualia’ are the mark of conscious life – a feature that seems irreducibly ‘mental’ (for a detailed discussion of qualia, see §§11.3–11.3.5).

      Adrian’s confusions about the ego

      2.3 John Eccles and the ‘Liaison Brain’

      Eccles’s achievement

      After studying medicine at Melbourne University, John Eccles (1903–1997) went to Oxford in 1925 as a graduate student to work with Sherrington, who was at that time engaged in research with Liddell on the characteristics of

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