I'm wrestling with the notion of events in indeterministic worlds. Suppose that given an event type and a world we can in principle tell if the event occurs in that world. (Indeed we could represent an event type as a subset of possible worlds). Further suppose one can tell if two worlds are identical up to some point in time. I am tempted to conclude that one can then define the time of occurrence of an event type in a given world. However, I'm bothered by the consequence that events would "occur" as soon as they become inevitable.
The only fix I've been able to find involves dealing with partial worlds -- i.e. worlds with histories only up to some point in time -- but this seems terribly ad-hoc and at odds with Lewis' elegant notion of a possible world as encompassing of time and space which I would like to retain.