Inversion and Paradigm Collapse? in the Lower Sepik Languages, Papua New Guinea

Direct versus inverse inflectional systems are a commonplace feature of languages which signal their grammatical relations primarily by verbal agreement, such as many Amerindian languages or Tibeto-Burman languages of the Himalayas. Direct versus inverse systems are characterized by one inflectional pattern when a speech act participant or local person (first or second person) functions as actor to a non-speech act participant or nonlocal person (third person) as patient and another inflectional pattern when the opposite situation holds. Scenarios in which local participants (first and second person) act on each other pose particular problems. The Algonkian languages of North America are the paradigm case of this grammatical inflectional pattern. As the Lower Sepik languages are morphologically complex languages which express grammatical information almost exclusively through verbal morphology, they, not unexpectedly, exhibit direct-inverse inflectional systems, and such a system was unquestionably a feature of Proto-Lower Sepik. However, while all six currently extant languages have such systems, each is different to a greater or lesser extent from the others, particularly in dealing with the pragmatically complex scenario in which local participants act on each other. I will employ a version of Optimality Theory to set out an analysis of the parameters of variation across the languages. Starting with a revision of Wunderlich's revision of my description of Yimas, I will propose 5 constraints that determine the patterns of verb inflection for transitive verbs in that language. I will then look at each language in turn and demonstrate how the variation among them is due to different ranking of these constraints, and in some cases, due to grammatical changes elsewhere, their apparent loss. The findings have important implications for procedures for the reconstruction of morphological systems in comparative linguistics, but also, due to the high degree of homophony in the paradigms in some languages, particularly in the inverse forms, and the disjunctive semantics of a number of the morphemes, for morphological theory more generally.