The Modal Openness of the Future
There's a simple and valid argument for fatalism based on a proposition which most analytic philosophers would accept. The assumption is this
- There is an actual world, alpha, which contains a complete history. Unlike other merely possible worlds, alpha is the possible world that "obtains".
Now, fatalism can be understood as the doctrine that no events have an intermediate chance of occurring. By a 'chance' I mean a single-case objective probability. By an 'intermediate' chance I mean a value between zero and one. If the chance of an event is one, then it is unpreventable--it's guaranteed to happen. If the chance of an event is zero, then its non-occurrence is unpreventable--it's guaranteed not to happen. Fatalism simply says that, for any event, its chance of occurring is either zero or one.
Now, consider the actual world, alpha. This includes a complete history. Hence, for every possible event E, either alpha entails that E occurs, or alpha entails that E doesn't occur. If alpha entails that E occurs, then the chance of E's occurring given alpha equals one. If alpha entails that E does not occur, then the chance of E's occurring given alpha equals zero. Using CH() to represent the chance function, this means that for arbitrary E, either
- CH(E | alpha) = 0, or
- CH(E | alpha) = 1.
- CH(alpha) = 1.
- CH(E) = 1.
- CH(E) = 0.
To avoid fatalism the initial assumption must be rejected. We must either deny that there is an actual world (i.e., we must deny that any possible world which includes a complete history obtains), or we must deny that possible worlds must include a complete history, in particular, a complete future history. Call that denial the modal openness of the future thesis. I maintain that the future is modally open. As contingencies are resolved, the modal changes. Things that were possible may not now be possible. Things that are necessary may not always have been necessary.