 There are two other notable features of “Causation as Influence”. It contains Lewis’s most comprehensive defence of the transitivity of causation. This principle was central to Lewis’s theory of causation from the earliest days, but had come under sustained attack over the years. And the paper has a brief attack on non-Humean theories that take causation to be a primitive. Lewis says that these theories can’t explain the variety of causal relations that we perceive and can think about. These passages mark an interesting change in what Lewis took to be the primary alternatives to his counterfactuals based reductionism. In 1973 the opponents were other kinds of reductionists; in 2000 they were the non-reductionists.