 The fundamental claim of relative identity-the claim the various versions of the idea have in common-is that, as it seems in the passenger/person case, it can and does happen that \(x\) and \(y\) are the same \(F\) and (yet) \(x\) and \(y\) are not the same G. Now it is usually supposed that if \(x\) and \(y\) are the same \(F\) (G etc.), then that implies that \(x\) and \(y\) are \(F\)s \((G\)s, etc.) If so, then the above schema is trivially satisfied by the case in which \(x\) and \(y\) are the same person but \(x (y)\) is not a passenger at all. But let us resolve to use the phrase ‘\(x\) and \(y\) are different \(G\)s’ to mean ‘\(x\) and \(y\) are \(G\)s and \(x\) and \(y\) are not the same \(G\)’. Then the nontrivial core claim about relative identity is that the following may well be true: