 An I-language, then, is something that is represented in the language faculty of an (idealized) individual at a particular stage of development. But it is not anything beyond the language faculty. Statements about I-languages being represented in the brain are “statements about the structures of the brain formulated at a certain level of abstraction from mechanisms” (1986: 33). In other words, to talk of the language faculty as representing some piece of information is simply one way among others of giving an abstract description of the language faculty, a human “organ” (Chomsky 1975: 10; Anderson &amp; Lightfoot 2000). Another way might be to describe it in chemical terms, but the representationalist description is—for reasons just sketched—rather more helpful than a chemical one within the context of explaining language acquisition. A grammar for an individual, a linguistic theory in other words, is an abstract statement of this I-language, but what it purports to describe is their language faculty, not something external to it.