 Language theorists have varying conceptions of what it is for a language to be realized. For David Lewis, a language in the abstract (which for him amounts to a pairing of sentences and meanings) is realized in a population when it describes a convention governing their behaviour, in the specific sense summarized in  Section 2.  Lewis, then, takes a non-idiolectal perspective. For Noam Chomsky, in contrast, a language is realized in an individual if it is “represented” in that individual’s “language faculty”, a component of their brain. The goal of linguists working in the Chomskian tradition is to make what is represented explicit in the form of a theory, a grammar, for that individual. This, then, is an idiolectal perspective. There is a twist, however. The brain properties that most interest Chomsky are species-wide rather than unique to any individual, so the “individual” is essentially the product of an idealization, useful for helping us to understand linguistic competence, a human biological trait. Still, we can persist in calling this an idiolectal perspective in that it eschews any essential role for languages of discrete linguistic communities.