Abstract
Some causal situations appear similar but causally different. Preemptive prevention offers such an example. However, it is difficult to capture the causal difference. In fact, it resists analysis. I discuss Collins’ s account of causal difference, and argue that it is not adequate. I also argue that the causal difference is not analyzable in terms of either dependence or production. I then examine some non-reductive account of causal difference, and claim that the sense of causal difference has yet to be specified. Preemptive prevention shows that the concept of causation, whether it is reducible to something else or not, still requires some further scrutiny.