This article examines the methodological foundations of historical studies in the field of Islamic and Shiʿi thought, with particular emphasis on the dual processes of description and explanation as constitutive components of scholarly justification. The study aims to clarify the nature of historical inquiry by distinguishing between purely descriptive approaches and descriptive–analytical approaches that seek to explain historical phenomena through causal, rational, and narrative models. Employing a qualitative and analytical method grounded in epistemological analysis, the article surveys major theories of historical explanation and investigates their application within religious and doctrinal research. The findings demonstrate that explanatory historical studies are inseparable from justificatory frameworks, especially in contexts where belief, truth, and epistemic authority are presupposed. The article further argues that coherentism and reliabilism represent the two most influential methodological approaches governing justification in Shiʿi historical studies, each yielding distinct outcomes in the interpretation of sources and propositions. The study concludes that greater methodological clarity regarding justification, source selection, and explanatory models can significantly reduce ambiguities in contemporary historical research and contribute to more rigorous and epistemically grounded studies of Shiʿi intellectual tradition.