The causal efficacy of composites: a dilemma for interventionism

This paper argues that the interventionist account of causation faces a dilemma concerning macroscopic causation – i.e., causation by composite objects. Interventionism must either require interventions on a composite object to hold the behavior of its parts fixed, or allow such interventions to vary the behavior of those parts. The first option runs the risk of making wholes causally excluded by their parts, while the second runs the risk of mistakenly ascribing to wholes causal abilities that belong to their parts only. Using as starting point Baumgartner’s well-known argument that interventionism leads to causal exclusion of multiply realized properties, I first show that a similar interventionist exclusion argument can be mounted against the causal efficacy of composite objects. I then show that Woodward’s (2015) updated interventionist account (explicitly designed to address exclusion worries) avoids this problem, but runs into an opposite issue of over-inclusion: it grants to composites causal abilities that belong to their parts only. Finally, I examine two other interventionist accounts designed to address Baumgartner’s argument, and show that when applied to composites, they too fall on one horn (exclusion) or the other (over-inclusion) of the dilemma. I conclude that the dilemma constitutes an open and difficult issue for interventionism.