فهرست نشریات علمی دسترسی آزاد ایران

This diachronic, cross-disciplinary study examines how doctoral theses vary over time and across academic disciplines in their use of evaluative language. Drawing on the Engagement subsystem of the Appraisal framework (Martin & White, 2005), the analysis is based on a corpus of 24 British theses, representing both soft and hard fields across three historical periods: 1950–1952, 1982–1984, and 2014–2016. The findings indicate a marked increase in the use of monoglossic resources, rising from 7.5% to 19% across the time span. This points to a movement toward more authoritative and assertive expressions of stance. Disciplinary differences also emerged; although heteroglossic resources remained prominent in both areas, students in the soft disciplines more frequently employed attribute and acknowledge, while those in the hard sciences favored entertain, reflecting epistemic caution even in evidence-driven writing. By focusing on the underexplored doctoral thesis genre, this study highlights how novice scholars negotiate rhetorical positioning both diachronically and across disciplinary contexts. The results carry pedagogical implications for English for Academic Purposes and supervisory practice. Thesis extracts and discipline-specific models can be used to heighten students’ awareness of stance strategies, support their progression from expansive to more contractive positioning, and equip supervisors with a shared metalanguage for offering feedback.