 What constitutes the direction of the causal relation? Why is this direction typically aligned with the temporal direction from past to future? In answer to these questions, Lewis (1979) argues that the direction of causation is the direction of causal dependence; and it is typically true that events causally depend on earlier events but not on later events. He emphasises the contingency of the latter fact because he regards backwards or time-reversed causation as a conceptual possibility that cannot be ruled out a priori. Accordingly, he dismisses any analysis of counterfactuals that would deliver the temporal asymmetry by conceptual fiat.