This study provides a critical examination of the hermeneutical foundations of a key text in Fatimid Ismāʿīlī esoteric exegesis: Asās al-Taʾwīl by al-Qāḍī al-Nuʿmān al-Maghribī (d. 363/974). It is aimed to identify four core principles underlying his hermeneutical system: the interdependence of exoteric and esoteric meanings, the symbolic nature of Quranic language, the exclusive authority of the Imam in matters of interpretation, and a typological worldview in which natural and historical phenomena serve as symbols for spiritual realities. Detailed analysis of al-Qāḍī al-Nuʿmān’s interpretations across prophetic narratives, theological verses, and legal rulings reveals five fundamental problems: epistemological circularity and interpretive exclusivism, semantic relativism arising from the absence of stable linguistic rules, a practical disjuncture between theoretical commitments and interpretive practice, structural bias toward legitimizing Ismāʿīlī hierarchy, and a tendency to undermine prophetic dignity and monotheistic concepts. By such a study, it could be demonstrated that these methodological and epistemological problems are closely tied to the historical-discursive context of the Fatimid Caliphate, where al-Qāḍī al-Nuʿmān’s system functioned as an ideological instrument for legitimizing Fatimid rule against Abbasid rivals, engaging intellectually sophisticated converts, and managing extremist movements. On this basis, it can be concluded that taʾwīl in this system serves not as a method for discovering textual meaning but as a tool for the reproduction of institutional power and epistemic authority, highlighting the need for critical reflection on the relationship between esoteric hermeneutics and political legitimation in classical Islamic thought.