The Semantic Basis of Externalism

Michael McKinsey

Many defenders of externalism in the philosophy of mind have forgotten their semantic roots, or so I will contend here. Among these are the externalists who maintain that their view is compatible with the principle that we can have privileged, non-empirical knowledge of the contents of our own thoughts, and who defend this compatibility thesis by insisting that externalist theses are about metaphysical, but not logical or conceptual, dependency relations between cognitive properties and external objects. This insistence, I maintain, is a sign of deep confusion. The dependence on external facts, or wideness, of the property expressed by a given cognitive predicate, such as 'believes that water is wet' or 'is thinking that Cicero is an orator', is not a function of some mysterious a posteriori metaphysical connection that the property happens to bear to external objects. Rather, it is a function of the wide meaning of, or the wide semantic contribution made by, a crucial component of the predicate, a component such as a name, an indexical pronoun, or a natural kind term. To expose the bankruptcy of the metaphysical strategy, I will examine its recent use by McLaughlin and Tye in their 1998 paper "Externalism, Twin Earth, and Self-Knowledge." I will argue that their view defends compatibilism at the cost of implying that the wide meanings of the words contained in the 'that'-clause of a cognitive ascription are strictly irrelevant to what is said by that ascription, and that, as a result, their view can provide no cogent account of why such ascriptions predicate wide cognitive properties. I will also argue that McLaughlin and Tyeís view is shown false by some obvious and well established semantic facts. These same facts also show that the principle of privileged access which they wish to defend is false. I conclude by trying to explain why so many contemporary defenders of externalism have been led to ignore the semantic facts that provide the primary motivation for their view.