 Despite the fact that Prior was able to provide a notion of contingency—contingencyQ—for his logic Q, it is difficult to downplay the awkwardness of the fact that the most natural expression of contingency—contingency∃—is unavailable to him; it is, recall, a theorem of Q that, necessarily, there are no contingent∃ beings—\(\Box\neg\exists \sfx\, \Diamond\neg \exists \sfy\,\sfx=\sfy\). Thus, although seemingly well-motivated by his strict actualist metaphysics, the fact that Prior cannot consistently assert that he himself might not have existed, that he himself is a contingent∃ being, arguably throws strict actualism into doubt: as Deutsch (1990: 92–93) observes,