 Chomsky claims that the truth of an I-language attribution is not preserved by substituting terms that have the same extension. That is, even when two human beings do not differ at all on what expressions are grammatical, it may be false to say that they have the same I-language. Where H is a human being and L is a language (in the informal sense) and R is the relation of knowing (or having, or using) that holds between a human being and a language, Chomsky holds, in effect, that R establishes an intensional context in statements of the theory: