So far, the speaker-hearer's linguistic intuition can be defined in such a way as to impose problems of phonemic and morphological analysis. Conversely, this analysis of a formative as a pair of sets of features cannot be arbitrary in a descriptive fact. From C1, it follows that an important property of these three types of EC suffices to account for the requirement that branching is not tolerated within the dominance scope of a complex symbol. This suggests that the systematic use of complex symbols is rather different from the extended c-command discussed in connection with (34). By combining adjunctions and certain deformations, the notion of level of grammaticalness does not readily tolerate a stipulation to place the constructions into these various categories.
see also: WikiPedia -- Chomskybot