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1. Externalism and Environmentalism
There is a view of the mind that began life as a controversial philosophical thesis, and then, much like an aging rock group, evolved into respectability. Indeed, it became common sense. According to this view, minds are to be assimilated to the category of substance. That is, minds are objects that possess properties. Indeed, minds can, to some extent, be conceived of as relatively similar to other bodily organs. Just as the heart circulates blood, the kidneys process waste, the mind thinks. According to the official version of this view, the major difference between the mind and these other organs is that the mind is a nonphysical substance. The brain and mind are, thus, distinct entities; the former a physical organ operating exclusively on mechanical principles, the latter a nonphysical organ operating according to principles of reason. The philosophical thesis from which this view was born was spelled out by Descartes, and its association with him is sufficiently robust for it to be called the Cartesian conception.
The Cartesian conception has famously been ridiculed as the myth of the ghost in the machine. And it has been Descartes' decision to make the mind ghostly (i.e., nonphysical) that has drawn the principal fire from dissenters. The dissenters' case here has been largely successful, and, today, [End Page 5] not many would describe themselves as Cartesians in this sense. Ryle's expression, however, has another facet. Not only is the mind a ghost, but it is one that is in a machine. And while the revolt against ghostly views of the mind has been overwhelmingly successful, criticism of this second aspect of Descartes' view has, until recently, been comparatively muted. This changed with the development of a view that came to be known as externalism.
The term 'externalism' in the philosophy of mind typically denotes a family of views, deriving from the work of Hilary Putnam (1975), Tyler Burge (1979, 1986), and certain work on indexicals associated, principally, with David Kaplan (1980), and all united by the idea that mental states, in some sense, are not in the head. Specifying the content of the clause in some sense, however, is no easy matter. Species and sub-species of externalism abound. Forms of externalism that assert the external location of mental states are contrasted with those that assert merely their external individuation (see, for example, McDowell 1986 and McGinn 1989 versus Macdonald 1990) Forms of externalism that admit a conceptually separable internally constituted component of mental states are contrasted with those that deny such a component. Weak externalism is commonly contrasted with strong, and one would look in vain for any unified construal of these qualifiers (contrast, for example, Forbes 1987, McGinn 1989, and Macdonald 1990).
Nevertheless, for the purposes of this paper, externalism in all its forms, possesses two essential theses, one concerning the nature of the states to which the externalist thesis applies, and the other concerning the properties of those states in virtue of which it applies. The first thesis is that externalism applies only to the so-called propositional attitudes. It applies to beliefs, desires, hopes, fears, expectations, anticipations, and the like, all of which are (i) attributed to a subject by way of a that-clause, and (ii) are individuated, in part, by way of the proposition that follows this clause. The second thesis is that the externalist claim applies to such states because they possess semantic content; because they are individuated by way of the proposition that follows the that-clause.
This means that the scope of externalism is severely restricted: it applies only to that relatively small group of mental states that have their contents essentially (i.e., propositional attitudes and possibly experiences—on some views of experience). What we might regard as the nuts [End Page 6] and bolts of cognition, processes, such as perceiving, remembering, thinking, reasoning, whereby we arrive at, or come to have, propositional attitudes, these are left outside the scope of externalism. That is, externalism as it is commonly understood, is...