  There are several responses to Plantinga's argument, differing in their metaphysical underpinnings. The first involves the possibilist's thesis that there are individuals that are not actual. (See Lewis's (1986).) In that case, what exists in a world does not exhaust what exists simpliciter. Bush is around to serve as a constituent of a proposition, even with respect to worlds in which he does not exist, because he exists simpliciter by existing in other worlds. The possibilist can thus claim that the truth of (P1) does not entail that, if p is true in w, then p exists in w; rather, it only entails that p and all its constituents exists.