Note that the notion of level of grammaticalness is rather different from nondistinctness in the sense of distinctive feature theory. For one thing, a subset of English sentences interesting on quite independent grounds is not to be considered in determining the levels of acceptability from fairly high (eg (99a)) to virtual gibberish (eg (98d)). Presumably, a descriptively adequate grammar does not readily tolerate the ultimate standard that determines the accuracy of any proposed grammar. Clearly, the fundamental error of regarding functional notions as categorial is not quite equivalent to problems of phonemic and morphological analysis. Let us continue to suppose that relational information suffices to account for the system of base rules exclusive of the lexicon.
see also: WikiPedia -- Chomskybot