  Chomsky rarely states the argument from the poverty of the stimulus  in its general form, as Cowie has done here. Instead, he typically  presents it via an example. One of these concerns learning  how to form ‘polar interrogatives,’ i.e., questions  demanding yes or no by way of answer, via  a mechanism known as ‘auxiliary   fronting.’[5]  Suppose that a child heard pairs of sentences like the following: