On Pied-piping of Predicative Phrases in Non-restrictive Relative Clauses

This paper investigates the immobility of predicative phrases in English non-restrictive relative clauses (NRRCs). Even though wh-words can pied-pipe a variety of constituents in NRRCs unlike in restrictive relative clauses and wh-questions, where a wh-word cannot be c-commanded by any lexical heads within a displaced phrase, predicative phrases such as APs, VPs, and predicate NPs cannot be fronted in this construction. In this paper, I ascribe this prohibition on the pied-piping of predicative phrases in NRRCs to a general property of non-restrictive relative extraction. I adopt Postal's (1994, 1998) idea that the extraction in NRRCs always leaves behind null resumptive pronominals in its extraction sites, and this property prevents constituents from being extracted if they have no substitutable pronominal. I show that there is no predicate pronominal in English, making the extraction of predicative phrases unavailable in NRRCs.