Abstract

Many philosophers of mind are concerned to defend the thesis called physicalism ; many others are concerned to refute it. Nevertheless, there is no generally agreed on idea of what physicalism is, and why it should matter whether the mental is physical. My thesis consists of four essays whose concern is with what physicalism is in its most plausible version, and what the importance of the thesis might be for the philosophy of mind. ;I begin with the question of whether it is possible to hold physicalism in a nonreductive form. Nonreductive physicalism is a doctrine that divides into two parts. The first part--the physicalist part--is that mental properties and facts supervene on physical properties and facts. The second part--the nonreductivist part--is that this supervenience thesis does not imply that mental properties and facts are reduced to physical properties and facts. In chapter one, I argue that, when properly understood, these two claims are not cotenable. ;In chapter two, I consider a different way of developing nonreductive physicalism. ;My discussion of nonreductive physicalism has a conditional conclusion: nonreductive physicalism reduces to reductive physicalism, and thus, if one wants to be a physicalist, one must be a reductive physicalist. Accordingly, in chapter three, I turn to reductive physicalism: the thesis that mental properties simply are physical properties. ;In the final chapter, I assess the reasons for believing physicalism. Physicalists have a number of different reasons for believing their doctrine, but perhaps the most widespread is the idea that one should believe physicalism because to renounce it would be, as Schiffer has put it, "to renounce the scruples of the natural scientist". I reply that this is a mistake born from missing an ambiguity in the word 'physical'. In one sense, 'physical' applies to a property or fact which the empirical sciences are in the best position to describe. In another sense, 'physical' applies to a property or fact which a certain sub-class of the empirical sciences are in the best position to describe, namely, the subclass which includes contemporary physics, chemistry, biology and neuroscience. What is at issue in the philosophy of mind is physicalism where 'physical' has this second stricter sense. However, under that interpretation, to renounce physicalism is not, I argue, to renounce the scruples of the natural scientist. Moreover, under that interpretation, there is no strong pressure to revise our conception of what a mental property is in order to ensure the truth of physicalism.