Nevertheless, the theory of syntactic features developed earlier may remedy and, at the same time, eliminate an abstract underlying order. On our assumptions, the notion of level of grammaticalness appears to correlate rather closely with the traditional practice of grammarians. This suggests that the speaker-hearer's linguistic intuition delimits an important distinction in language use. Let us continue to suppose that relational information cannot be arbitrary in irrelevant intervening contexts in selectional rules. To characterize a linguistic level L, the earlier discussion of deviance is rather different from a stipulation to place the constructions into these various categories.
see also: WikiPedia -- Chomskybot