<p>According to the Principle of Alternative Possibilities (PAP), someone is morally responsible for something she has done only if she could have done otherwise. Since Harry Frankfurt’s seminal article on PAP, the literature has mostly concerned whether Frankfurt-type cases are counterexamples to the principle. There is still no consensus on that. The positive case for PAP has received much less attention. This article addresses a source of support for PAP that appears frequently in the literature, but is rarely discussed at length. This source of support involves cases where it seems someone is not morally responsible because she is unable to do otherwise. I argue that these cases provide poor support for PAP. My argument relies on the thought – developed recently by Alfred Mele, Romy Jaster, Chandra Sripada, and David Storrs Fox – that our abilities are often fallible. The challenge for PAP’s adherents is to provide a better positive case for their principle.</p>