Positional licensing and the preference for nonconcatenative morphology in Dinka

Dinka morphophonology has been cited as a challenge for strict item-and-arrangement approaches to morphology, because of the apparent preference for nonconcatenative morphology: most morphological categories are marked solely by phonological changes in a monosyllabic root (Andersen 1992 et seq.). This paper introduces the novel observation that the phonological properties involved in these changes are restricted in overt suffixes. We develop an analysis in which vocalic suffixes undergo CV metathesis into the root, driven by a positional licensing constraint that prefers vowel contrast to be expressed in the root, resulting in changes in vowel quality with predictable lengthening. An item-and-arrangement analysis derives this relationship and accounts for two key properties of Dinka morphology: nonconcatenative morphology is consistent and additive (cf. Sande 2022), while apparent cases of extended exponence are predictable outcomes of vowel harmony or epenthesis conditioned by a complex tonal melody.