Authorial Voice and Knowledge Construction in Vietnamese Aviation Engineering Textbooks: A Systemic Functional Analysis of Mood and Modality
Abstract
This paper examines authorial voice and knowledge positioning in five Vietnamese aviation engineering textbooks (5,399 clauses) through Systemic Functional Linguistics analysis of Mood and Modality. Five key features emerge: (1) Declarative mood dominance (98.8%) enforces unilateral knowledge transmission; (2) systematic suppression of human agency via non-interactive Subjects (96.9%) and implicit Subjects (13.3%); (3) affirmation as epistemic default (97.0%), with negation reinforcing rather than opening interpretive space; (4) law-like knowledge through predictive sẽ (44.6% of Probability), encoding causal necessity rather than temporal futurity; (5) graduated obligation with near-equal distribution of high-obligation phải (51.5%) and median-obligation cần/nên (46.6%). Complex Modality occurs in 1.2% of clauses. Together these features define a declarative knowledge culture: authoritative transmission, graduated regulation, high-context embedding. The study contributes to non-Anglophone Systemic Functional Linguistics and to the linguistic anthropology of education
Keywords: Systemic Functional Linguistics; interpersonal meaning; Mood; Modality; aviation engineering textbooks; linguistic anthropology; authorial voice; declarative knowledge culture