In the discussion of resumptive pronouns following (81), a descriptively adequate grammar may remedy and, at the same time, eliminate the traditional practice of grammarians. From C1, it follows that the natural general principle that will subsume this case delimits a descriptive fact. So far, the appearance of parasitic gaps in domains relatively inaccessible to ordinary extraction is, apparently, determined by irrelevant intervening contexts in selectional rules. It must be emphasized, once again, that the descriptive power of the base component is unspecified with respect to the system of base rules exclusive of the lexicon. Of course, the speaker-hearer's linguistic intuition suffices to account for an abstract underlying order.
see also: WikiPedia -- Chomskybot