The nativist perspective on second language acquisition

Two central questions in SLA research are (i) what are the properties of an L2 grammar that give rise to observed performance, and (ii) how does an L2 learner arrive at that grammar? Three arguments are offered to support the view that answers to these questions cannot be achieved without assuming that L2 learners have innate linguistic knowledge that determines the form their grammars take: constraints on grammars that are specifically linguistic, the non-randomness of the features that learners identify in constructing grammars, and selective persistent divergence from native speakers on properties for which there is positive evidence in the input.