Voice in Transition: A Diachronic-Typological Study of Mori Atas

This thesis presents a diachronic-typological study of the voice system of Mori Atas, an Austronesian language spoken in southeastern Sulawesi, Indonesia. I treat voice as an interface mechanism that manages a recurring tension between syntactic prominence (subjecthood, shaped by predicate-argument structure) and discourse prominence (topichood, shaped by information-structural needs). On this view, a transitional voice system is not defined primarily by the loss of voice contrasts, but by a redivision of labour across the grammatical devices that regulate these two kinds of prominence.

The first part of the thesis (Chapters 1-8) provides a synchronic analysis of Mori Atas verbal morphology, pronominal paradigms, TAM, clause types, grammatical relations, and information structure. The description reveals a mixed system in which inherited voice morphology continues to track topicality in key environments, including a one-topic economy in complex clauses, while subject-related dependencies are increasingly mediated by other resources. The second part (Chapters 9-11) situates Mori Atas typologically and reconstructs the pathway by which this profile emerges through both retention and innovation relative to Philippine-type, topic-prominent systems.

I argue that two linked innovations drive the transitional outcome. First, the Actor Voice domain narrows. Reflexes of PMP *paN- and *paR- are reanalysed as valency-changing prefixes (poN-, pe(N)-), and transitive free roots allow optional AV <um>. Where <um> is absent, pronominal clitics regulate syntactic prominence (Actor > Undergoer), while discourse effects are expressed through word order, outer operators, prosody, and/or coreferential NPs. This shift yields a predicate-local economy in topic management, consistent with a system in which syntactic and discourse prominence are no longer bundled by the same morphological choice. Second, the Undergoer Voice marker in-/<in> develops passive properties in unmarked declaratives, promoting the Undergoer to subject status while suppressing the Actor.

This thesis refines the notion of an Austronesian transitional voice system by arguing that the crucial change is not simply morphological erosion, but a reweighting of the division of labour between syntactic and discourse prominence across the clause.