Mutual Manipulability and Causal Inbetweenness

Carl Craver's mutual manipulability criterion aims to pick out all and only those components of a mechanism that are constitutively relevant with respect to a given phenomenon. In devising his criterion, Craver has made heavy use of the notion of an ideal intervention, which is a tool for illuminating causal concepts in causal models. The problem is that typical mechanistic models contain non-causal relations in addition to causal ones, and so the question as to the applicability of ideal interventions arises. In this paper, I first show why top-down interventions in mechanistic models are likely to violate the standard conditions for ideal interventions under two familiar metaphysics of mechanistic models: those based on supervenience and realization. Drawing from recent developments in the causal exclusion literature, I then argue for the appropriateness of an extended notion of an ideal intervention. Finally, I show why adopting such an extended notion leads to the surprising consequence that an important subset of mechanistic interlevel relations come out as causal. I call the resulting metaphysical account by the name `causal inbetweenness'