This article is devoted to the analysis of methodological features of cognition in the sciences of fundamental jurisprudence, revealed on the basis of the history of political and legal doctrines. The paper considers two complementary approaches: genetic (historical) and systematic (philosophical). The comparative analysis demonstrates that the first approach involves reconstructing the relationship of theoretical propositions with the specific historical context of their origin, taking into account the social, economic, political and cultural determinants of the era. The second approach is aimed at identifying the inherent logic and value of ideas, regardless of the conditions of their genesis. The analysis of the teachings of thinkers from different eras illustrates the limitations of the exclusive use of any of the methods. Historical analysis, revealing the origin of doctrines, does not fully explain their logical structure and universal significance, whereas a philosophical approach used in isolation from the historical context risks losing its connection with social practice. The author comes to the conclusion that these methods of cognition are equally important in the field of political and legal thought.