Real knowledge: the problem of content in neural epistemics

functions of their physical substrates. The second program follows the naturalistic line of metaphysics, emphasizing the need to study mind and cognition as parts of natural reality. Boldly put, this line claims that cognitive science is the science of the brain. Advocates have even suggested that we should eliminate the traditional conception of knowledge, and supplant it with neurophysiology. The naturalistic program is represented most prominently by thinkers such as Paul Churchland and Patricia Churchland. A Cartesian presumption Both of these programs fall prey to the Myth of the Given, although for different reasons and in different respects. They both try to secure, in Sellars’ words, “a privileged stratum of fact” in terms of which to account for cognitive phenomena. Fodorians have mental symbols, naturalists have brains. Both symbols and brain states figure as ‘given’ in these theories, that is, they serve as the intrinsic basis of cognition. The main difference between the two approaches is that symbols are primarily logical items, whereas brains are physically real. If, as I have intimated, cognitive science should take into account both the logical and the real aspect of knowledge, then clearly a meeting of minds is in order. This study explores the possibility of combining the insights of computational and naturalistic approaches to cognition. In this respect it contains nothing new, apart from certain accents in the manner of presentation. Similar proposals for a neurocomputational approach have been made by others in the recent past (see, for example, Churchland 1989a; Clark 1989; Churchland and Sejnowski 1992). What is new, however, is my attempt to combine the approaches in a coherent way that enables us to move beyond the naturalistic fallacy identified by Sellars. So long as cognitive science remains wed to the Myth of the Given, it will never be able to free itself from charges of reductionism and foundationalism. This becomes particularly clear in discussions of mental content, where it is typically argued that the semantics of cognitive states must be determined by intrinsic factors if these states are to count as cognitive. This presumption appears to be shared by rationalists and naturalists alike. Whether the content of belief is thought to be fixed by the combinatorial syntax of mental symbols, by synaptic arrangements in neural nets, or by causal or counterfactual relations to properties of distal objects, it is destined to be treated as given, that is, as being dictated to us by one of the Masters of the universe. A truly balanced account of knowledge, or so I shall argue, requires that we give up this idea. Beyond the naturalistic fallacy 11 Seen from a slightly different perspective, the present study is a critique of the representationalist framework of cognitive science. Both the symbolist program of cognitive psychology and the connectionist or subsymbolist program in neuroscience are committed to the idea that cognition is the processing of internal representations (cf. Cummins 1989). Now, a closer look at the notion of representation as it is used in these theories reveals a fundamental reductionist presumption, namely, that representations must be given in order to count as cognitively relevant. In the terminology developed in chapter five, there is a tendency in cognitive science to make representations either ‘superstrong’ (endowed with intrinsic content) or ‘superweak’ (cognitively irrelevant). For example, a familiar objection against computational models is that computations as such are meaningless: having no content of their own, they must be irrelevant for our understanding of knowledge. Similarly, neural models of the mind are often charged with ‘changing the subject’. Neural activity has no intrinsic meaning; therefore, neuroscience cannot explain cognition, although it may have many things to say about the anatomy and physiology of the brain. I think that the presumption of intrinsic content underlying these arguments is wrong. It belongs to an essentially Cartesian frame of mind that is deeply entrenched in modern philosophy. Descartes inculcated us with the notion of man as an outside observer, a thinking substance locked inside a biological machine. The Cartesian subject has access to the external world only through his mental representations of that world. These representations are given to the internal subject, but they are not physically real. I shall argue for the exact opposite of this view, namely, that representations are physically real and that they are not given.3 Notice that my concern with ‘givenness’ and with the naturalistic fallacy, unlike Sellars’ and Rorty’s, is not based on linguistic or social considerations. Social constraints on knowledge appear to me to be very much on a par with other external factors weighing on internal structure. I take them to be real and important, but not special. Habits, practices and institutions, most notably including those of language communities, control the formation of structured responses and behavioral dispositions in individual human beings. Language is a behavioral disposition like others, a set of neural structures specifically calibrated to respond to certain external pressures. Hence, an adequate understanding of language requires a more general theory of how physical and social mechanisms alike bear on the individual’s performance. From this purview, it would be methodologically unwise to start with language, or to think that only language matters.