  The first type of inadequacy is, of course, endemic to any kind of  empirical inquiry: it is simply the problem of the underdetermination of theories by their evidence. Cowie has argued elsewhere that  underdetermination per se cannot be taken to be evidence for  nativism: if it were, we would have to be nativists about  everything that people learn (Cowie 1994; 1999). What of the second kind of impoverishment? If the evidence about language  available to children does not enable them to reject false  hypotheses, and if they nonetheless hit on the correct grammar, then  language learning could not be a kind of scientific inquiry, which  depends in part on being able to find evidence to weed out incorrect  theories. And indeed, this is what Chomsky argues: since the  pld are not sufficiently rich or varied to enable a learner  to arrive at the correct hypothesis about the grammar of the language she is learning, language could not be learned from the pld.