If the position of the trace in (99c) were only relatively inaccessible to movement, the fundamental error of regarding functional notions as categorial does not affect the structure of a corpus of utterance tokens upon which conformity has been defined by the paired utterance test. Of course, this selectionally introduced contextual feature cannot be arbitrary in the traditional practice of grammarians. We will bring evidence in favor of the following thesis: the appearance of parasitic gaps in domains relatively inaccessible to ordinary extraction is not subject to a general convention regarding the forms of the grammar. For one thing, the descriptive power of the base component does not readily tolerate the levels of acceptability from fairly high (eg (99a)) to virtual gibberish (eg (98d)). We have already seen that the notion of level of grammaticalness is rather different from a parasitic gap construction.
see also: WikiPedia -- Chomskybot