Philosophical Foundations of Neuroscience. P. M. S. Hacker
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matter at all, but a logical or conceptual one. The type of explanation is categorially different, and explanations in terms of agential reasons and motives, goals and purposes, are not reducible to explanations of muscular contractions produced as a consequence of neural events (see chapter 16). But equally, such explanations are not couched in terms of the activities of the mind, conceived as an independent substance with causal powers of its own. In this sense, Penfield’s dilemma is a bogus one. He was perfectly right to think that one cannot account for human behaviour and experience in terms of the brain alone, but wrong to suppose that the idea that one might be able to do so is an intelligible empirical hypothesis as opposed to a conceptual confusion. He was also wrong to suppose that the alternative is accounting for human behaviour and experience in terms of the causal agency of the mind, and wrong again in thinking that that too is an empirical hypothesis. There is no need whatsoever to impale oneself on either of the horns of Penfield’s dilemma.
The hypothesis that mind–brain interaction can explain human behaviour is logically incoherent
Once these presuppositions are jettisoned, it becomes easier to see why the explanation of human behaviour in terms of the interaction of the mind (conceived as an independent substance) and the brain is misconceived. It is not a false empirical hypothesis, but a conceptual confusion. For inasmuch as the mind is not a substance, indeed not an entity of any kind, it is not logically possible for the mind to function as a causal agent that brings about changes by acting on the brain. This is not an empirical discovery, but a conceptual clarification. ( But it is equally mistaken to suppose that substituting the brain for the Cartesian mind is any less confused. That too is not an empirical hypothesis, but a conceptual muddle, which likewise stands in need of conceptual clarification.)
Neither epileptic automatism nor electrode stimulation of the brain support dualism
Consequently, Penfield was mistaken to think that what so impressed him – namely, the phenomena of epileptic automatism and the various facts that characterize electrode stimulation of the brain – constitute empirical support for a dualist hypothesis. Epileptic automatism does not show that the mind has become disconnected from the ‘highest brain mechanism’ to which it is normally connected, and by which it is supplied with energy of an as yet unknown form.26 What it shows is that during an epileptic seizure, as a consequence of the abnormal excitation of parts of the cortex, the person is temporarily deprived of some of his normal powers (including memory, the ability to make decisions, emotional sensitivity and a sense of humour), while other powers, in particular those for routine actions, are retained. The phenomena are indeed striking, but they amount to a dissociation of powers that are normally associated, not to a disconnection of substances that are normally connected. They do not show that the brain is a computer or that the mind is its programmer. The brain is no more a computer than it is a central telephone exchange (the previously favoured analogy), and the mind is no more a computer programmer than it is a telephonist. It is perfectly true that the ability to continue routine tasks unreflectively is useful (and the expression ‘short-term programming’ is an apt metaphor here). It is also true that the purposes pursued by someone are not the purposes of his brain. But it does not follow from this that they are the purposes of his mind. They are the purposes of the human being – and they are to be understood in terms of facts about human life, social forms of life, antecedent events, current circumstances, agential beliefs and values and so forth, not in terms of neural events and mechanisms. But it is, of course, true that, but for the normal functioning of the brain, a human being would not have, and would not be able to pursue, the normal kinds of purposes that we do pursue.
The various phenomena that characterize electrode stimulation of the brain are similarly misconstrued by Penfield. The case of interference with the ‘speech cortex’ does not show that there is any such thing as a ‘concept mechanism’ in the brain that stores non-verbal concepts that can be selected by the mind and then presented to the speech mechanism to be matched to the word that represents the concept. That is picturesque mythology, not an empirical theory. Words are not names of concepts, and do not stand for concepts, but rather express them. Concepts are abstractions from the use of words. The concept of a cat is what is common to the use of ‘cat’, ‘chat’, ‘Katze’, etc. The common features of the use of these words is not something that can be stored in the brain or anywhere else independently of a word (or symbol) that expresses the concept. The patient whom Penfield describes could not think of the word ‘butterfly’ with which to identify the object in the picture presented to him. He knew that the object belonged to a class which resembles a different class of insects (viz. moths), and tried, equally unsuccessfully, to think of the word for members of the second class. This temporary inability is incorrectly described as knowing the concept but being unable to remember the word for it. The supposition that the mind might be presented with non-verbal concepts from which to choose presupposes that there is some way of identifying non-verbal concepts and distinguishing one from the other independently of any words or symbols that express them. But that makes no sense (see §§15.1–15.2).
It is certainly interesting that Penfield found that electrode stimulation could not induce either belief or decision. But this does not show that believing and deciding are actions of the mind, any more than it shows that they are not actions of the brain. It is true that they are not actions of the brain – but that is not an empirical fact that might be shown to be the case by an experiment. Rather, there is no such thing as the brain’s believing or deciding (any more than there is such a thing as checkmate in draughts). But it is also true that they are not actions of the mind either. My mind does not believe or disbelieve anything – I do (although, to be sure, that is no action). Nor does it decide – it is human beings that decide and act on their decisions, not minds.
That the exercise of mental powers is a function of the brain does not show that behaviour and experience are explicable neurally
Penfield objected vehemently to the suggestion that the mind is a function of the brain, and supposed that if it were, then the mind would cease to exist during sleep or epileptic automatism. The suggestion is unclear, but one may surely say that the distinctive powers of intellect and will of a creature that has a mind are a function of the creature’s brain (and of other factors too). It does not follow (as Penfield evidently feared it would) that the behaviour and experience of such a creature in the circumstances of life is explicable in neural terms. But nor does it follow that the mind ceases to exist during sleep or epileptic seizure – any more than one’s knowledge and beliefs, intentions and projects, cease to exist when one is asleep. Penfield was rightly impressed by the fact that ‘the mind develops and matures independently throughout an individual’s life as though it were a continuing element’ (MM 80). But he was misled by his unquestioned assumption that the mind is a kind of agent. Had he thought of the mind in more Aristotelian terms as a set of powers and capacities (second-order powers), he would have been closer to the truth, and less prone to conceptual illusion. For the continuous possession of powers and capacities is not interrupted by sleep or even by epileptic automatism, even though the agent cannot exercise some of his normal powers during the seizure. And the developing unity of a person’s mind is not the development of a substance distinct from the human being himself, but rather the emergence of a determinate character and personality, an intellect with certain distinctive characteristics and a will with a coherent array of preferences, all of which are traits of the person – of the living human subject who has rights, duties and obligations, and who is responsible for his acts, actions and activities.
What Penfield thought the less plausible alternative to dualism is the view currently favoured
Penfield thought that a form of Cartesian dualism is more probably correct than what he conceived to be the alternative: namely, ascribing understanding, reasoning, volition and voluntary action, as well as deciding, to the brain itself. It is very striking and important that the strategy that Penfield conceived to be altogether improbable is precisely the route that is currently adopted by the third generation of neuroscientists, who ascribe psychological functions to the brain. This is the subject of the next chapter.
Notes