A Grammatical and Linguistic Analysis of Noun Declension in Pashto Language: Systematic Rules Beyond Temporal Influence

This research investigates the grammatical mechanisms underlying noun declension (inflection) in Pashto, an Eastern Iranian language with distinctive ergative-absolutive alignment. In Pashto morphosyntax, proper nouns and common nouns undergo systematic case marking that has historically posed pedagogical and analytical challenges for both native and non-native learners. This study addresses a critical gap in Pashto grammatical scholarship by demonstrating that temporal categories (tense) do not directly govern noun case assignment. Rather, noun declension is triggered by two principal factors: (1) the presence of adpositions (prepositions and postpositions) that establish syntactic relationships, and (2) the ergative case marking required for subjects of transitive verbs in past perfective constructions. Through a library-based descriptive-analytical methodology drawing on classical and contemporary Pashto grammatical literature, this paper synthesizes existing theoretical frameworks and proposes three operational rules consolidated into a comprehensive 'Golden Rule' for noun declension. The findings reveal that morphological changes in Pashto nouns represent obligatory grammatical requirements rooted in the language's ergative typology, serving to maintain semantic clarity and syntactic coherence. Specifically, feminine nouns ending in /a/ (ـه) shift to /e/ (ـې), while masculine nouns ending in /ay/ (ی) shift to /i/ (ي) when entering the oblique case. The study acknowledges that additional noun classes exist in Pashto whose case behavior requires separate investigation; the scope of this analysis is deliberately limited to the two most pedagogically prominent alternation classes. This analysis provides accessible models for accurate Pashto usage and contributes to broader linguistic typology by offering empirical evidence of ergativity in contemporary Indo-Aryan and Eastern Iranian languages, with significant implications for language education and computational linguistics.