  However, argued Chomsky, just as conditioning was too weak a learning strategy to account for children's ability to acquire language, so  too is the kind of inductive inference or hypothesis-testing that  goes on in science. Successful scientific theory-building requires  huge amounts of data, both to suggest plausible-seeming  hypotheses and to weed out any false ones. But the data children have access to during their years of language learning (the ‘primary linguistic data’ or ‘pld’) are highly  impoverished, in two important ways: