David Spurrett

People differ in the extent to which they discount the values of future rewards. Behavioural economists measure these differences in terms of functions that describe rates of reduced valuation in the future – temporal discounting – as these vary with time. They measure differences in preference for risk – differing rates of probability discounting – in terms of similar functions that describe reduced valuation of rewards as the probability of their delivery falls. So-called ‘impulsive’ people, including people disposed to addiction, tend to choose rewards in patterns that are described by unusually steeply sloped discount functions. The empirical literature is ambivalent as to whether this applies to pathological gamblers (PGs) who manifest most other behavioural patterns associated with addiction, with different, equally careful studies suggesting opposite conclusions (Petry & Casarella 1999; Holt, Green & Myerson 2003). This puzzle may arise from the fact that most previous experiments on discounting behaviour were not designed so as to allow effects of high temporal discounting to be distinguished from effects of low probability discounting. (Addiction has sometimes been associated with the latter because it seems to involve, at least in the starting addict, under appreciation of risk.) Our research project investigates both forms of discounting behaviour and their relationship to severity of risk of PG in a community sample of South African gamblers.

Bhaskar's articulation of his ‘transcendental realism' includes an argument for a form of causal emergence which would mean the rejection of physicalism, by means of rejecting the causal closure of the physical. His argument is based on an analysis of the conditions for closure, where closed systems manifest regular or Humean relations between events. Bhaskar argues that the project of seeking closure entails commitment to a strong reductionism, which in turn entails the impossibility of science itself, and concludes that we should endorse causal emergence. I argue that Bhaskar's case grossly overreaches itself, and that he fails to establish the emergentist conclusions which he asserts. Consequently his programme poses no significant threat to physicalism.