 The argument for substance may be criticized on several grounds. First, the step leading from [2] to [3] relies on the assumption that a name fails to refer with respect to a possible world at which its actual-world referent does not exist. This amounts to the controversial assumption that names do not function as what Nathan Salmon has called “obstinately rigid designators” (Salmon 1981, 34). Secondly, the step leading from [3] to [4] relies on the assumption that a sentence that is neither true nor false with respect to some possible world fails to express a sense. As Wittgenstein was later to realize, the case of intuitively senseful, yet vague sentences plausibly constitutes a counterexample (cf. PI Section 99). Lastly, one may question the assumption that it makes sense to speak of a final analysis, given that the procedure for analysing a sentence of ordinary language has not been made clear (See PI, Sections 60, 63–4, and Section 91). 