 What are the prospects of a theory according to which existence is a universal, genuinely contingent and transient property of individuals? Such a view requires that the domain of quantification varies from world to world and time to time, as everything that is exists but different individuals exist at different possible worlds and at different times, in which case the domain of quantification varies from world to world and time to time. In that case, Alien from above is true. So fault must be found with the earlier argument that the truth of Alien is inconsistent with the thesis of actualism. One response found in the literature rejects the last step, insisting that there are general claims that could have been true, and so are true at some accessible possible world, without there being specific instances of those claims that are true at those accessible worlds. In nonmodal environments, the quantified sentence ∃xφ(x) is true just in case there is some witness o that satisfies the condition φ(x). That condition fails, however, for quantified sentences true at a merely possible world. The model theory for a model language—with its space of possible worlds and individuals populating the domains of possible worlds—contains, like everything else if actualism is true, only actually existing entities. Still, sentences like Alien are true and so there are merely possible worlds at which ∃x¬A∃y(y=x) is true.  There is no individual of which ¬A∃y(y=x) is true in virtue of which the quantified sentence is true, although there would have been had that merely possible world been actual. This is perhaps more clear when we turn from sentences being true with respect to merely possible worlds to propositions being true at merely possible worlds. There is a world w at which the existential proposition [there is something such that there is no actual thing identical to it] is true but there is no singular proposition [there is no actual thing identical to o] true at w as there is no such entity o. Had w been actual, however, then there would have been such an entity and it is this fact that grounds the truth of the existential proposition at w. (The classic source for this distinction is [Adams 1981]. See also [Fine 1985] and [Fitch 1996].)  This suggestion, then, runs contrary to the standard semantics for quantificational sentences, which reduces the truth or falsity of existential and universal sentences to the truth or falsity of their instances, when extending that semantics to truth at a world. The suggestion also requires a distinction between truth at a world, in terms of which the model theory for modal operators is given, and truth in a world, which involves the notion of considering what would have been had a nonactual world been actual. (For more on this distinction and the problem of the contingency of existence more generally, see the entry on the on possibilism-actualism debate.)