The standard criticism of verificationism is that the verificationist criterion of meaning is self-defeating, fails to work for unprovable mathematical truths, and so on. This criticism shows that the criterion is not necessary for meaningfulness. And it's the necessity that the verificationists cared most about. But is verifiability sufficient for meaningfulness?
Well, first say that p is positively (negatively) verifiable iff there is a possible world where p is strongly (i.e., not just incrementally) empirically confirmed (disconfirmed). Say that x is an rmor iff x is a round mimsy or x is red. Then the claim, p, that George is a rmor admits of both positive and negative verification. In some worlds where George is an observed green triangle, p is strongly disconfirmed (because x is neither red nor round), while in some worlds where George is an observed red triangle, p is strongly confirmed (because x is red).
But of course, p is meaningless because "mimsy" is meaningless.
Maybe, though, the verifiability criterion is counterfactual instead of modal. So, p is verifiable in w iff it is true in w that were requisite observations of the items involved in p made, p would be positively or negatively verified. The above example fails then because in a world where George is a round green peg, it is false that p would be either positively or negatively verified were appropriate observations made.
But just vary the case. Stipulate that an ortum is an observed red thing or an unobserved mimsy. Then in any world that contains an ortum, the claim that George is an ortum is verifiable. For were George observed, he wouldn't be an unobserved mimsy, and one could see whether he's an observed red thing or not. But, again, "George is an ortum" is meaningless because "mimsy" is.
