The Absent Relata Problem: Can absences and omissions really be causes?

Things that happen are often causally attributed to an absence or an omission. Prima facie, this presents a puzzle: the absent relata problem. How can the cause-effect relation obtain when the relata are absences? In the present paper we consider three accounts, due to Beebee, Dowe, and Schaffer, and find them unsatisfactory. Instead we recommend an approach to the problem that derives from the belief that understanding of causation should be built upon contrastive causal explanation, combined with an investigation of the actual processes of causal production (which is the main business of science, rather than philosophy). Elsewhere we have argued that this approach gives a convincing account of causal explanation in terms of absences and omissions. However, it might be thought, as Beebee has indeed maintained, that while absences and omissions can figure in causal explanations, they cannot genuinely be causally efficacious. It might also be supposed that absences and omissions function only preventively, and that the real causal production is to be found in what would have happened if there had not been an absence or an omission – ‘causality by the other path’, as we call it. We refute this supposition, which is integral to Schaffer’s quaternary account of causation, using an argument concerning intervention. This allows us to uphold the causal efficacity of absences and omissions, provided that talk of absences and omissions is understood to be a loose kind of reference which indicates actual worldly states of affairs.