 Brogaard &amp; Salerno (2007) pose a dilemma for Williamson: either we hold the context fixed in this kind of counterpossible reasoning, or we don’t. If we don’t, then (2) does not follow from (1). In particular, the context at which (2) comes out false is one at which the closest antecedent worlds are possible and, to be sure, at those worlds, 0 is not 1. But if we hold the context fixed, then what does follow is just the following counterpossible: 