Abstract Despite decades of research on school leadership and instructional supervision, to the best of the authors' knowledge no study in the global literature has explicitly argued that the principal's core function—analogous to the teacher's core function of teaching—is to serve as the cognitive quality controller of classroom learning and assessment. This theoretical synthesis paper identifies and diagnoses a foundational conceptual gap at the intersection of three established but disconnected research streams: instructional leadership theory, Bloom's Revised Taxonomy and HOTS research, and assessment quality research. Drawing on a narrative mapping of these streams, we argue that school systems worldwide have defined the principal's role through administrative and managerial competencies (EMASLIM framework; Permendiknas No. 13/2007), while supervision of instructional cognitive quality is treated as one of many coequal functions rather than the primary one. Consequently, the primary theoretical contribution of this paper is fundamentally diagnostic-forensic, aiming to expose this structural blind spot (epistemic vacancy) as the definitive root cause. We propose that this misalignment is a significant contributing factor to persistently low higher- order thinking skills (HOTS), literacy, and critical thinking outcomes particularly in Indonesia and Southeast Asia, where recent studies confirm that 81-98% of classroom assessments operate at the lowest cognitive levels (Sirri et al., 2025; Setyorini, 2025; Fakhrillah structural blind spot; epistemic vacancy; cognitive leveling; cognitive depth; EMASLIM; cognitive domain primacy; 90-day intervention model; theoretical synthesis.
Permana et al. (2026) studied this question.