This article discusses morphological case variation, arguing that individual cases are not syntactic objects or features but PF interpretations of a range of different underlying syntactic relations. Nevertheless, it turns out that case variation can, to a large extent, be analyzed in terms of only two atomic ‘ingredients’: event licensing of NPs and PF marking of the licensing relation (where marking is analyzed in terms of Chomskyan case stars). Ergative is a Voice/ag*-case, whereas accusative is a v*-case, licensed under c-command by Voice/ag (ergative and accusative marking thus being two sides of the same coin). Individual cases in case-expanding morphological/PF case systems, it is argued, behave like viruses, striving to expand beyond their original ‘reasonable’ domain.
