 Klagge (1995) objected to this line of argument. He pointed out that Paull and Sider include an extrinsic property M in the supervenient set A, but only intrinsic properties P and Q in the subvenient or base set B. And, he claimed, if we allow that there are the sorts of property-forming operations required to construct extrinsic property M, then Paull and Sider have not exhaustively characterized worlds w and w*. For, given those property-forming operations, it is plausible that there will, for instance, be a property P# that can be defined as follows: P# =df Px &amp; ∃y(y≠x). (Basically, a thing is P# just in case something else is P.) a in w and c in w* differ on this property; a has P# while c does not. That is right. But Klagge took that to show that w and w* do not provide a counterexample to the strong supervenience of A on B after all. That, however, does not follow. It would follow only if a and c thereby counted as B-discernible, and they do not. Paull and Sider stipulate that B contains only P and Q. Thus, a and c are B-indiscernible, despite the fact that a has P# and c does not.