 The most widely-discussed way of fleshing out this picture takes the form of a theory of linguistic meaning which Lewis  (1983, 1984) presents as a sort of toy theory, not really true but close enough to the truth for certain dialectical purposes.  This theory takes the form of an account of what it is for an interpretation function to be admissible (“correct”, “intended”) for a given population. An interpretation function is a mapping from linguistic expressions to semantic values of appropriate kinds (e.g. mapping predicates to properties and sentences to propositions, or to functions from contexts to propositions). According to the account, an interpretation function is admissible for a population just in case it achieves the best overall balance of “use” and “eligibility”. An interpretation function’s “use” (or “charity”) score is higher the more it maps sentences that members of that population are strongly and stably disposed to assert to true propositions. An interpretation function’s “eligibility” score is higher the more natural the semantic values it assigns to words (and the simpler its rules for assigning semantic values to complex expressions). Sometimes there will be ties for first place, so that multiple interpretation functions will be admissible for a population. In such cases—and perhaps also in cases of near-ties—the population’s language contains semantic  indeterminacy.[48] 