On the Source of Interrogative Adverbs

Ambiguous questions like Why do they believe ( that ) she killed him? , where the interrogative word seems to refer to either clause, appear to offer counter-examples to the NP Ecology Constraint proposed in Cattell 1976. But sentences beginning with why are frequently not ambiguous in this way; and when they are ambiguous, they cannot always be explained by appeal to the theory that why has separate origins in the different clauses. Consequently, it is argued here that the derivation of why and other interrogative adverbs does not involve the movement of NP's, and therefore does not present counter-examples to the NP Ecology Constraint. An alternative explanation of why -questions is offered, which involves appeal to semantic and deictic criteria.