 There are three important things to note about the definition of causal dependence. First, it takes the primary relata of causal dependence to be events. Lewis’s own theory of events (1986b) construes events as classes of possible spatiotemporal regions. However, different conceptions of events are compatible with the basic definition (Kim 1973a; for an alternative broadly Lewisian take on events see McDonnell 2016 and Kaiserman 2017). Indeed, it even seems possible to formulate it in terms of facts rather than events (Mellor 1995, 2004).