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

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

      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

      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


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