The Syntax–Morphology–Discourse Interface in Null Argument Licensing: Reconsidering the Phase Impenetrability Condition in Kiswahili and EkeGusii

This study examines how syntax, morphology and discourse contribute to null argument constructions in Kiswahili and EkeGusii and assesses their implications for the Phase Impenetrability Condition (PIC). The licensing of null arguments in Bantu languages raises questions about the adequacy of phase-based locality restrictions in explaining grammatical dependencies involving unpronounced subjects and objects. Although the PIC restricts syntactic access across phase boundaries, Kiswahili and EkeGusii permit constructions in which argument features are expressed through verbal morphology without independent nominal phrases. The study adopts a qualitative comparative design involving purposively selected illustrative constructions from the two languages, analysed through morphological segmentation, syntactic comparison and discourse interpretation. The analysis draws on four principal constructions presented in the study and relevant published linguistic scholarship; no human participants or elicitation instruments are documented. The findings indicate that verbal markers encode features associated with unpronounced arguments, although their presence does not independently establish whether they function as agreement or pronominal elements. The analysis further demonstrates that discourse contributes to referential identification, while the PIC constrains the syntactic dependencies through which arguments are represented. The study concludes that null argument constructions do not necessarily violate phase-based locality and that their explanation requires distinguishing syntactic licensing, morphological realisation and discourse interpretation. It recommends further investigation of object marking, argument doubling and agreement dependencies across Bantu languages. The study contributes to Minimalist theory by clarifying the explanatory scope of the PIC and the role of grammatical interfaces in argument interpretation.