On Crane and Mellor's Argument against Physicalism

Abstract

In article recently published in Mind, Tim Crane and D.H. Mellor (1990) present a series of arguments against physicalism, view that entities, properties, relations and facts are really physical, and that the empirical world... just what a true complete physical science would say it contains (pp. 185-6). Many recent defenders of physicalism have relied on supervenience thesis, which states that two things will not be found to differ in any mental respect without also being found to differ in some relevant (non-trivial) non-mental respect as well. The physical excludes mental, according to supervenience physicalist, being that on which everything else, including mental, (p. 203). Crane and Mellor claim to have refuted all forms of physicalism. The final argument of their paper is directed against supervenience physicalist. They invite reader to consider a situation in which two individuals have at time t1 some qualitatively identical experiences PI and P2, respectively. Let us suppose, with Crane and Mellor, that PI causes by some later time t2 a mental state or property Ml in first individual and that P2 causes by t2 some mental state or property M2 in second individual. Let us also suppose that I, and I2 are non-mental states or properties (I for intrinsic) on which Ml and M2 are claimed to supervne at t2. Crane and Mellor's argument rests on assumption that there are two independent causal connections, one between P 's and M's, other between P 's and I's. They show that if connection bewteen P's and M's is indeterministic, it is possible for Ml ? M2 yet I, = I2, in conflict with supervenience thesis as stated above. I wish to point out here that Crane and Mellor have not refuted every version of supervenience physicalism. In particular, they have not refuted most wellknown recent version, viz. Donald Davidson's anomalous monism. Davidson does hold that mental supervenes on physical and that physical events can causally interact with mental events (1980, p. 208). This certainly appears to make his position a candidate for Crane and Mellor's attack on supervenience physicalism. Nevertheless, their attack fails. Why it fails becomes clear once we formulate Crane and Mellor's thought experiment in Davidson's own terms. The supervenience thesis states that two individuals will differ in some non-mental respect given that they differ in some mental repsect. The respects that Crane and Mellor have in mind are mainly properties. They rely on locutions an instrinsic non-mental property P causes a mental property M and the properties involved are causally related (p. 205). Surely this is not how Davidson would desribe situation. To begin with, Davidson describes one connection as holding between two events, not properties. According to Davidson, we can and do describe same event in either mental or physical terms. Despite these alternative descriptions, there is just one event. Furthermore, any mental event capable