 Salmon (1996) claims ‘something like a proof’ of this implication, from transworld identities to bare identities. He argues for what he calls Extreme Haecceitism, the view that transworld identities cannot be grounded in general facts about the individuals concerned. The purported proof goes as follows. We consider x in world w and y in world w2 and suppose, for reductio, that x = y and that this fact is reducible to (or grounded in, or entailed by) general facts about x in w and y in w2. But, says Salmon, the fact that x = x is not reducible (grounded, etc.) in this way, since it is a fact of logic. So, says Salmon, ‘x differs from y in at least one respect. For x lacks y’s feature that its identity with x is grounded in general (cross-world) facts about x and it’ (1996, 216), and hence (by Leibniz’s Law), x ≠ y, contrary to assumption. So if there are any transworld identities, those identities cannot be grounded in general facts about those individuals. They must be ‘bare’.