Event C causes event E if and only if there is a chain C, D1, …, Dn, E such that each member in the chain (except C) is counterfactually dependent on the event before it
In “Causation” (1973b), Lewis put forward an analysis of causation in terms of counterfactual dependence. The idea was that event B was counterfactually dependent on event A if and only if the counterfactual Had A not occurred, B would not have occurred was true. Then event C causes event E if and only if there is a chain C, D1, …, Dn, E such that each member in the chain (except C) is counterfactually dependent on the event before it. In summary, causation is the ancestral of counterfactual d