Timothy Williamson has argued for the radical conclusion that everything necessarily exists. In this paper, I assume that the conclusion of Williamson’s argument is more incredible than the denial of his premises. Under the assumption that Williamson is mistaken, I argue for the claim that there are some structured propositions which have constituents that might not have existed. If those constituents had not existed, then the propositions would have had an unfilled role; they would have been gappy. This gappy propositions view allows for a plausible response to Williamson’s argument. Additionally, a slight variant of the gappy propositions view allows for plausible defense of Linguistic Ersatzism from the problem of contingent non-existents (also known as the problem of aliens).