 Squaring the circle is a mathematical impossibility, in spite of Hobbes’ hopes. His achieving it, though, would have made no difference for those sick children. (9) should come out true for this reason, not because no possible world verifies the antecedent. For similar reasons, (8) should come out false. Against vacuism, some counterpossible pairs with opposite consequents should have different truth values (for a defense of vacuism, see Williamson 2007; for a discussion, see Berto et al. 2018).