Physicalism and mental causes: contra Papineau
In Philosophical Naturalism (1993), David Papineau defends physicalism, the thesis that all natural phenomena are physical. More precisely, Papineau's physicalism consists of two theses regarding supervenience and token congruence. His supervenience thesis states that two systems differ chemically, biologically, or psychologically with regard to their intrinsic, nonrelational properties only if they differ physically. His token-congruence thesis, denying epiphenomenalism, states that 'each dated mental occurrence is the same as some dated physical occurrence, even if we can't identify the mental type in question with any one physical type' (1993: 12). Papineau offers supervenience and token congruence as individually necessary and jointly sufficient for physicalism, adding that the world of physicalism is fundamentally constituted by physical phenomena. Papineau's physicalism allows for the correct use of nonphysical vocabulary, and denies that such vocabulary is always shorthand for physical properties. In Papineau's words: '... physicalism, as I have characterized it, allows that we often use nonphysical terminology, like 'sulphuric acid', 'thunderstorm', 'elephant', and 'thinking of the future', to group and categorize large-scale arrangements of physical facts. Moreover, physicalism allows that such special terminology isn't just a shorthand for complex physical properties: for in those cases where type identity fails, special categories cannot even in principle be specified in physical terms' (1993: 13). Still, according to Papineau, the special vocabulary is just a way of describing complexes of physical phenomena; it does not require the existence of any nonphysical substance. All substances are, then, physical, but not all correct ascription of properties is ascription of physical properties. In this respect, Papineau's physicalism is nonreductive and noneliminative: It does not require that all nonphysical vocabulary be reduced or eliminated. In particular, it does not require that psychological vocabulary be reduced or eliminated. As Papineau says, '... I don't in fact think that psychological categories are reducible to physical ones,' adding later that '... there is plenty of uncontentious empirical evidence that everyday psychology is true at just those points where it takes us beyond Dennett's [nonrealist] intentional stance' (1993: 44, 67). Why accept Papineau's physicalism? I shall argue that Papineau's answer yields a troublesome dilemma: either a dubious kind of causal