Introduction: Triggers for language variation

The aim of this chapter is to review the theoretical hypothesis put forth within Generative Grammar to account from language variation and to test whether they can be extended beyond cross-linguistic variation to other levels like the idiolectal, or to particular contexts like heritage language acquisition; (ii) to specify the implications of variation being restricted to the functional lexicon; (iii) to explore if further loci or triggers for variation should be taken into account.