Yates has recently argued that modal dispositionalism invalidates the axiom. Both Yates and Allen have advanced responses to the objection: Yates’s response proposes installing truth into the possibility biconditional, and Allen’s response requires that all properties be construed as being essentially dispositional. I argue that supporters of Borghini and Williams’s modal dispositionalist theory cannot accept these responses, given critical tenets of their theory. But, since these responses to the objection are the most plausible in the literature, I conclude that the (...) threat that Borghini and Williams’s modal dispositionalist theory invalidates the axiom still looms large. (shrink)