 The solution to the late preemption problem that Lewis cautiously endorses in his 1986c appeals to the notion of quasi-dependence. Consider a case that resembles the case of Billy and Suzy throwing rocks at a bottle. Suzy throws a rock (c) and shatters the bottle (e) in exactly the same way in which she does in the original case. But in this case Billy and his rock are entirely absent. In the original case, e is caused by but does not counterfactually depend on c, whereas in this second case e is caused by and does counterfactually depend on c. But the intrinsic character of the process leading from c to e is just the same in both cases. Thus, Lewis says, in the original case (with Billy also throwing), e quasi-depends on c. So “we could redefine a causal chain as a sequence of two or more events, with either dependence or quasi-dependence at each step. And as always, one event is a cause of another iff there is a causal chain from one to the other” (1986c, 206). (A related idea is pursued in Menzies 1996 and 1999.) Note that, this proposed definition of a causal chain notwithstanding, the quasi-dependence solution does not demand transitivity in the way that Lewis’s earlier solution to the problem of early preemption did: with back-up potential causes safely out of the way, in all cases of preemption (early and late), the effect should straightforwardly quasi-depend on its cause.