Interventionism, Agency and Causal Exclusion (L. de Bruin, V. Gijsbers)

Abstract

The causal exclusion argument – which suggests that mental properties, if not reducible to physical properties, are causally inefficacious – is the central argument in the debate between reductive and non-reductive physicalists. Recently, several authors (most notably Woodward) have argued that the interventionist approach to causation implies that the causal exclusion argument fails. Others (most notably Baumgartner) have defended the opposing view. We analyse the Woodward-Baumgartner debate and show that the two sides reduce to familiar views about supervenience, between which it is extremely hard to decide. Eronen & Brooks (2014) have responded to the dilemma thus posed for interventionism by putting forth a deflationary version of the theory, which saves clarity at the expense of being entirely silent on the metaphysical issues surrounding supervenience and emergence. We argue that another route is possible. Taking our cues from Jackson and Pettit's notion of causal relevance (Jackson & Pettit 1990) and an agency approach to interventionism (Gijsbers & De Bruin 2014) we show that there is an interpretation of interventionism which (1) respects all the usual constraints of physicalism, such as the causal closure of the physical; (2) does not make any controversial assumptions about supervenience; and yet (3) makes the mental causally relevant to the physical. If this interpretation is adopted, non-reductive physicalism is saved from the causal exclusion argument.