 This objection by the fatalist is surely right about one thing. If we cannot affect the past, it would be good to know why we cannot. One possible answer would be that which an A-theorist of time might give, namely that there is a fundamental ontological difference between the future on the one hand and the present and past on the other, which consists in the fact that the present and past are real or actual, while the future is not. And it is this fact, that the future is not real or actual, which means that it is open, can be affected by what happens now; and it is the fact that the present and past are real or actual which means that they cannot be affected by what happens now (Lucas 1989a, Tooley 1997).