 This intersubjective or objective constraint provides a normative, even if conventional, distinction between consistent and inconsistent language use, or between correct and incorrect rule following. Kripke and David Bloor correctly point out that this condition is not incompatible with Robinson Crusoe’s physical isolation (Kripke 1989, 112, n. 89; Bloor 1997). Now we can see the point of Kripke’s analogy between the impossibility of a private language and the impossibility of central planning. If, as in Mises’s argument, an economic agent has no extrinsic range of intersubjective and commensurable values—that is, the numerical market prices which are set independently by others—, then he has no rational and objective justification for choosing between alternative courses of action. Here exact numerical commensurability and explicit calculation rules are the basis for both objectivity and rationality. In contrast with Kripke’s analogy there is a strong opposing analogy between Neurath’s argument against private language and his defense of central planning. The analogy, as explained in connection with Neurath’s position towards Mises, above, reveals a common set of values that are coherent yet different from the ones involved in Mises’s argument.