The principle of alternate possibilities and "ought' implies 'can'
In a widely discussed article (Frankfurt 1969), Harry Frankfurt argued against, and claimed to have refuted, PAP. But he denied (1988: 95-96) that his rejection of PAP commits him to rejecting OIC. Presumably his position would appear less attractive if it were perceived as opposing not only the intuitions behind PAP, but also those behind OIC. David Widerker (1991), however, argued that OIC entails a component part of PAP (i.e. the part concerning blameworthiness), and that since Frankfurt's argument, if sound, would refute this component of PAP, Frankfurt is logically committed to rejecting OIC. Gideon Yaffe (1999) has come to Frankfurt's defence, claiming that OIC does not entail PAP, and arguing that Widerker's attempt to derive (part of) PAP from OIC is fallacious. Alex