 This criticism might be too quick. Stephen Yablo (1999) has argued that Vallentyne should best be understood as working within a very different metaphysical framework than Lewis. For Lewis, no (ordinary) object exists at more than one world, so Vallentyne’s contractions, being separate worlds, must contain separate objects. Hence \(x-t\) contractions can be nothing other than lonely duplicates, and the theory is trivial. Yablo suggests that the theory becomes substantive relative to a metaphysical background in which the very same object can appear in different worlds. If this is the case then we can get a grip on contractions without thinking about duplications — the \(x-t\) contraction of a world is the world that contains \(x\) itself, and as few other things as possible.