Harry Frankfurt is a philosopher noted for defending a compatibilistic view of free will. He is widely recognized for his paper “Alternate Possibilities and Moral Responsiblity” (link) in which he argues that the principle of alternate possibilities (PAP) is not necessary to assign moral responsibility. He does this through examples that have become quite popular, even being referred to as Frankfurt stories. This approach is considered, by some, to have successfully shown how moral responsibility can be assigned in a world in which PAP does not exist. Since Reformed theology affirms determinism and a compatibilistic view of free will (link), the Frankfurt stories are sometimes used to bolster their position (see this post as an example). But do Frankfurt stories do what their proponents claim?
What is PAP?
Frankfurt offers the following definition, which aligns with the idea of a libertarian free will (LFW).
This principle states that a person is morally responsible for what he has done only if he could have done otherwise.
He follows that with the following assessment:
the principle of alternate possibilities is false. A person may well be morally responsible for what he has done even though he could not have done otherwise.