The term grammar is systematically ambiguous between two ideas, as illustrated in Figure 7.1.

An internalized grammar is the internalized knowledge of a native speaker of English that enables him or her to make judgments

about language data. In particular, a native speaker, henceforth called an informant, can:

• make grammaticality judgments: The informant can differentiate a grammatical sentence (The girl depends on her computer) from an ungrammatical sentence (*The girl depend her computer).