 We can regiment the contingency of existence intuition as followings, letting A be the actuality operator, where Aφ is true with respect to a world w under an interpretation I just in case φ is true with respect to the distinguished world of I:  ◊∃x¬A∃y(y=x). Call this sentence Alien. The worry is that the truth of Alien carries ontological commitment to merely possible individuals and so the falsity of the thesis of actualism. One way to substantiate this worry is to invoke the Barcan Formula, or one of the mixing axioms proposed for modal operators and quantifiers in Ruth Barcan Marcus’s groundbreaking work in quantified modal logic [Marcus 1946], according to which all instances of the sentence ◊∃xφ(x) →∃x◊φ(x) are logical true. (In the foregoing formulas, φ(x) stands for any formula in which the variable x may or may not be free.) We can then transpose the modal and quantifier in Alien to derive ∃x◊¬A∃y(y=x). The truth of this second sentence evidently requires that there is something that is not actual, contrary to the dictates of actualism. The Barcan Formula, and in part for this very reason, is controversial and rejected by those that subscribe to a varying domains possible worlds semantics for modal discourse. So this line of argument is not likely to convince everyone that our modal intuitions lead to problems. 