Complexity in linguistic theory, language learning and language change

In this paper I discuss how the notion of complexity can be defined and operationalized to serve as a concept in linguistic research domains like typology, historical linguistics and language contact and acquisition studies. Elaborating on earlier work (Kusters 2003) I argue that a relative notion of complexity is to be preferred over an absolute one. With such a substantial notion, I show that possible objections raised against the concept of complexity are not valid. I work this further out for complexity in verbal inflectional morphology. Finally I demonstrate some intricacies of complexity with examples from variation and change in Quechua varieties.