History of Cognitive Neuroscience (Bennett/History of Cognitive Neuroscience) || Conceptual Presuppositions of Cognitive Neuroscience
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Conceptual Presuppositions of Cognitive Neuroscience
7.1 Conceptual Elucidation
In Philosophical Foundations of Neuroscience (Bennett and Hacker, 2003),1 we aimed to con-tribute to neuroscientifi c research in the only way in which philosophy can assist science not by offering scientists empirical theories in place of their own, but by clarifying the conceptual structures they invoke. The systematic elucidations we gave of sensation, perception, knowledge, memory, thought, imagination, emotion, consciousness and self-consciousness are not theories.2 Their purpose was to clarify the psychological concepts that cognitive neuroscientists use in their empirical theories. The conceptual clarifi cations we gave demonstrated numerous incoherences in current neuroscientifi c theorizing. They showed why these mistakes are committed and how to avoid them.
Criticisms of our work, from three of the leading philosophers who concern them-selves with cognitive neuroscience and its philosophical implications, Professors Churchland, Dennett and Searle, are the subject of this chapter. Responding to them will serve three purposes. First, it will defend and clarify further the fundamental philosophical principles that inform our work. Secondly, it will rectify a variety of misunderstandings and
1 Page references to this book will be fl agged PFN. The main critics of our book that we here address are Paul Churchland, in his critical notice Cleansing Science (2005), John Searle and Daniel Dennett, both of whom responded to us at an authors and critics session at the meeting of the American Philosophical Association (Eastern Division) in New York, December 2005, and whose papers, together with a version of the current chapter, were published in Bennett et al., 2007. All page references to their critical essays are to this publication. 2 Searle, in his APA paper, objected to our insistence that our observations are not a theory. He asserted that a conceptual result is signifi cant only as a part of a general theory (p. 122). If by a general theory he means an overall account of a conceptual network, rather than mere piecemeal results, we agree. Our denial that our general accounts are theoretical is a denial that they are logically on the same level as scientifi c theories. They are descrip-tions, not hypotheses; they are not confi rmable or refutable by experiment; they are not hypothetico-deductive, and their purpose is neither to predict nor to offer causal explanations; they do not involve idealizations in the sense in which the sciences do (e.g. the notion of a point-mass in Newtonian mechanics), and they do not approximate to empirical facts within agreed margins of error; there is no discovery of new entities and no hypothesizing entities for explanatory purposes.
History of Cognitive Neuroscience, First Edition. M. R. Bennett and P. M. S. Hacker. 2013 Blackwell Publishing Ltd. Published 2013 by Blackwell Publishing Ltd.
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misinterpretations. Thirdly, it will advance further criticisms of views that we hold to be mistaken.
Cognitive neuroscience is an experimental investigation that aims to discover empirical truths concerning the neural foundations of human faculties and the neural processes that accompany their exercise. A precondition of truth is sense. If a form of words makes no sense, then it wont express a truth. If it does not express a truth, then it cant explain any-thing. Philosophical investigation into the conceptual foundations of neuroscience aims to disclose and clarify conceptual truths that are presupposed by, and are conditions of the sense of, cogent descriptions of cognitive neuroscientifi c discoveries and theories.3 If con-ducted correctly, it will illuminate neuroscientifi c experiments and their description, and the inferences that can be drawn from them. In Philosophical Foundations of Neuroscience we delineated the conceptual network formed by families of psychological concepts. These concepts are presupposed by cognitive neuroscientifi c research into the neural basis of human cognitive, cogitative, affective and volitional powers. If the logical relations of impli-cation, exclusion, compatibility and presupposition that characterize the use of these concepts are not respected, invalid inferences are likely to be drawn, valid inferences are likely to be overlooked, and nonsensical combinations of words are likely to be treated as making sense.
In this book, History of Cognitive Neuroscience, we have delineated some of the major experimental investigations into cognitive neuroscience over the past century or so. We have outlined what the neuroscientists in question thought they had discovered and what con-clusions they drew from their work. We have subjected their descriptions of the results of their experiments to critical analytic scrutiny. For, we have argued, it is common for experi-ments and consequences taken to follow from them to be fl awed by conceptual confusions and unclarities. Our criticisms have been wholly analytic, concerned not with errors of fact or experimental infelicity, but only with conceptual error.
Some philosophers, especially in the USA, have been much infl uenced by Quines philosophy of logic and language, according to which there is no signifi cant difference
3 Dennett, in his reply to our book at the APA, seemed to have diffi culties with this thought. In his criticisms (p. 79), he quoted selectively from our book: Conceptual questions antecede matters of truth and falsehood (PFN 2); What truth and falsity is to science, sense and nonsense is to philosophy (PFN 6). From this he drew the conclusion that in our view philosophy is not concerned with truth at all. However, he omitted the sequel to the fi rst sentence:
They are questions concerning our forms of representation, not questions concerning the truth or falsehood of empirical
statements. These forms are presupposed by true (and false) scientifi c statements, and by correct (and incorrect) scientifi c
theories. They determine not what is empirically true or false, but rather what does and does not make sense.
(PFN 2, emphasis added)
He likewise omitted the observation on the facing page that neuroscience is discovering much concerning the neural foundations of human powers, but its discoveries in no way affect the conceptual truth that these powers and their exercise . . . are attributes of human beings, not of their parts (PFN 3, emphasis added). As is patent, it is our view that philosophy is concerned with conceptual truths, and that conceptual truths determine what does and does not make sense.
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between empirical and conceptual truths.4 According to Quine, the sentences of a theory face experience as a totality, and are confi rmed holistically. So, from a theoretical point of view, a Quinean will hold that there is no essential difference between the sentence Memory is knowledge retained and the sentence Memory is dependent upon the normal functioning of the hippocampus and neo-cortex. But this is wrong. The former is a conceptual truth, the latter a scientifi c discovery. Memory is knowledge retained is an expression of a rule of description (or norm of representation) in the guise of a statement of fact, whereas Memory is dependent upon the normal functioning of the hippocampus is a statement of fact. To confuse and confl ate the two is akin to confusing or confl ating the rules of chess with moves in chess, or a measure with a measurement. Note that the distinction between conceptual and empirical truth is not an epistemologi-cal, but a logical, one. A conceptual proposition ascribes internal properties or relations, whereas an empirical proposition ascribes external ones. A conceptual truth is partly constitutive of the meanings of its constituent expressions, whereas an empirical proposi-tion is a description of how things stand. Precisely because such statements are partly constitutive of the meanings of their constituent expressions, failure to acknowledge a conceptual truth (e.g. that red is darker than pink) is a criterion of lack of understanding of one or another of its constituent expressions. But that does not make the distinction epistemological.
It would be similarly mistaken to suppose that the theorems of the differential calculus, which are non-empirical truths, were confi rmed holistically by the predictive success of Newtonian mechanics (as is implied by the Quinean doctrine). They were confi rmed by mathematical proofs. It would be equally erroneous to suppose that vixens are female is confi rmed by the success of zoological theory or that bachelors are unmarried is confi rmed by the sociology of marital habits. So too, that red is darker than pink is not verifi ed by confi rmation of the theory of colour, but rather is presupposed by it. Non-empirical propo-sitions, whether they are propositions of logic or mathematics or straightforward conceptual truths can be neither confi rmed nor infi rmed by empirical discoveries or theories.5 Con-ceptual truths delineate the logical space within which facts are located. They determine what makes sense. Consequently, facts can neither confi rm nor confl ict with them.6
4 Paul Churchland proposes, as a consideration against our view, that Since Quine, the bulk of the philosophical profession has been inclined to say no to the suggestion that there are necessary truths, constitutive of meanings, that are forever beyond empirical or factual refutation 2005, p. 474). We doubt whether he has done a social survey (do most philosophers really think that truths of arithmetic are subject to empirical refutation together with any empirical theory in which they are embedded?); and we are surprised that a philosopher should think that a head-count is a criterion of truth. 5 For canonical criticism of Quine on analyticity, see Grice and Strawson, 1956. For more recent, meticulous criticism of Quines general position, see Glock, 2003. For a contrast between Quine and Wittgenstein, see Hacker, 1996, ch. 7. Williamson (2006), construes conceptual truths as epistemological and argues that there are no such truths. His criticisms of that notion of conceptual truth, whether valid or not, are therefore irrelevant to the con-ception that we advance. 6 It is mistaken to suppose, as Churchland does (2005, pp. 467f), that the Cartesian claim that the non-physical mind can affect events in the physical world via its action on the pineal gland is refuted by the fact that it would
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A fi nal point of clarifi cation: it has been suggested by critics that we are committed to something called Ordinary Language Philosophy (Churchland, 2005, p. 465). The sug-gestion is misplaced. We are concerned with ordinary language only when the problematic concepts we are dealing with are non-technical concepts of natural language. But we have no qualms or hesitations about discussing technical concepts in neuroscience (in other sciences or in mathematics) and pointing out when they are misused. Nor, as is patent in Philosophical Foundations of Neuroscience, do we have qualms about identifying conceptual incoherences that stem from the misuse of technical concepts. That they are misused is not, in our view, shown by whether their application does or does not accord with that of non-technical concepts. It has also been suggested that we possess and deploy something called a theory of meaning (Churchland, 2005, p. 476). If a theory of meaning is a set of axioms, formation and transformation rules that will allow the derivation of the truth conditions of any well-formed sentence of a language, then we certainly have no theory of meaning. Our observations about the meanings of words and about the boundaries between sense and nonsense are not a part of any theory, but clarifi cations of the concepts of word-meaning, sense and nonsense. Churchland supposes that our claim that a word is used according to standards of correct use (rules of use) is a theoretical claim. It is no more theoretical than the claim that law-abiding citizens act in accordance with the law.
7.2 Two Paradigms: Aristotle and Descartes
Philosophical refl ection on human nature, on the body and soul, goes back to the dawn of philosophy. The polarities between which it fl uctuates were set out by Plato and Aristotle. According to Plato, and the Platonic-Christian tradition of Augustine, the human being is not a unifi ed substance, but a combination of two distinct substances, a mortal body and an immortal soul. According to Aristotle, a human being is a unifi ed substance, the soul (psuche) being the form of the body. To describe that form is to describe the characteristic powers of human beings: in particular, the distinctive powers of intellect and will that char-acterize the rational psuche. Modern debate on this theme commences with the heir to the Platonic-Augustinian tradition: namely, the Cartesian conception of human beings as two
violate the law of Conservation of Momentum. The Cartesian claim could be empirically refuted only if it made sense. For it to make sense, it would have to provide criteria of identity for immaterial substances but that is just what it does not do. We would have to know what counts as an immaterial substance, how to distinguish the same immaterial substance again on a subsequent occasion, and how to distinguish one such substance from two or twenty or 200 (each of which may be thinking the very same Cartesian thoughts). But we do not. We would have to understand what it would be for an immaterial substance to possess causal powers to act on a material substance. Then we might fi nd out that immaterial substances do not in fact possess such powers. But we do not understand what it would be, for the idea is incoherent. If one thinks that the supposition that an immaterial sub-stance causes movements of a human beings limbs when he moves voluntarily is subject to empirical disconfi rma-tion, then we must also think that it is, in principle, subject to empirical confi rmation that something conceivable could confi rm it, even if nothing in fact does. But what experimental result could conceivably confi rm that the movement of ones arm, when one moves ones arm voluntarily, is caused by an immaterial substance?
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one-sided things, a mind and a body. Their two-way causal interaction was invoked to explain human experience and behaviour.
The greatest fi gures of the fi rst two generations of twentieth-century neuroscientists, e.g. Sherrington, Eccles and Penfi eld, were avowed Cartesian dualists. The third generation retained the basic Cartesian structure, but transformed it into brainbody dualism: substance dualism was abandoned, but structural dualism retained. For n...