 The counterfactual in (iii) is to be understood in terms of possible worlds: it says that in the nearest possible world(s) where C does not occur, the probability of E is less than or equal to y. (There needn’t be a single value that the probability would have been. It can take on different values in the closest possible worlds, as long as all of those values are less than or equal to y.) On this account, the relevant notion of ‘probability-raising’ is not understood in terms of conditional probabilities, but in terms of unconditional probabilities in different possible worlds.