Free acts and chance: Why the rollback argument fails

The 'rollback argument,' pioneered by Peter van Inwagen, purports to show that indeterminism in any form is incompatible with free will. The argument has two major premises: the first claims that certain facts about chances obtain in a certain kind of hypothetical situation, and the second that these facts entail that some actual act is not free. Since the publication of the rollback argument, the second claim has been vehemently debated, but everyone seems to have taken the first claim for granted. Nevertheless, the first claim is totally unjustified. Even if we accept the second claim, therefore, the argument gives us no reason to think that free will and indeterminism are incompatible. Furthermore, seeing where the rollback argument goes wrong illuminates how a certain kind of incompatibilist, the 'chance-incompatibilist,' ought to think about free will and chance, and points to a possibility for free will that has remained largely unexplored.