 Now, if something is given to us as a set and we ask whether it is identical with an arbitrarily chosen object \(x\), this specifies a clear condition that settles the matter. The only questions that remain for the theory \(Z\) concern its existence principle: Do we know that the Subset Axiom and other set existence principles are true, and if so, how? The question of existence is thus laid bare. We do not approach it by attempting to justify a principle that implies the existence of sets via definite descriptions which we don’t yet know to be well-defined.