According to the Principle of Alternative Possibilities (PAP), a person is morally responsible for what he has done only if he could have done otherwise. This principle, or something like it, seems quite plausible. And it has played an important role in arguments for the incompatibility of moral responsibility with causal determinism, divine foreknowledge, and divine providence. Yet, despite it's intuitive appeal, PAP has not gone unchallenged. Beginning with Harry Frankfurt over forty years ago, a number of counterexamples (known as "Frankfurt examples") have been offered. Since that time, a sizeable literature has developed around Frankfurt's challenge.

The traditional strategy for attacking PAP is to attack it directly by attempting to provide a counterexample to the principle, as Frankfurt did. However, an alternative approach is to attack some other principle that PAP is connected to in an important way. I pursue the second strategy, targeting the following principle: PAP(CC): When an agent is non-derivatively morally responsible for an action, he is so partly in virtue of having been able to have done otherwise.

I think the fundamental intuition behind an alternative possibilities requirement on moral responsibility is found in PAP(CC). Although PAP does not entail PAP(CC), if one rejects PAP(CC), then, absent other arguments in favor of PAP, one has little reason to accept PAP. I argue that PAP(CC) is false. Some Frankfurt examples---so-called "complete blockage" cases---are successful counterexamples to PAP(CC). However, since PAP does not entail PAP(CC), it remains possible that PAP is true even if PAP(CC) is false. For this reason, I consider two other arguments offered in support of PAP: the W-defense and the Deontic Maxim Defense. I argue that these arguments are unsuccessful. I conclude that even if PAP is in fact true, we have very little reason to believe that it is. After more than forty years of debate, it is time to say farewell to PAP.