The paper focuses on the conceptualization of the philosophy of (Czech) history in the early work of Czech philosopher Karel Kosík. Although Kosík historical narrative has been later predominantly interpreted as the opposite to the Zdeněk Nejedlý's statements, authors show that Kosík's texts from 1950s were strongly influenced by Nejedlý's conception of the Czech progressive traditions and in a dialogical way represented a serious attempt in rethinking Nejedlý's attitudes.
The main Kosík's historical synthesis Czech Radical Democracy (1958) was then a result of such endeavour and to certain extent represented his forthcoming revisionist period. In this book Kosík revised his Marxist methodology towards a consistent application of a historical materialism and backed away from a claim to offer a coherent philosophy of Czech history as Nejedlý did.
Secondly, the paper explains why Kosík's interest in the revolutionary democrats may be perceived as innovative in that time. A genealogy of the concept of "radical democracy"/"radical democrats" can be traced up to the revolutionary events of 1848.
The second part of the text shows how gradually the meaning of the radical democracy was established in the Czech historical discourse and how it became the object of various controversies. In this vein Kosík is here not the explorer of the term, rather he follows many previous interpretations, especially those produced during interwar period.
What is new by Kosík's attitude is an attempt to establish the Czech radical democracy as a compact political stream with its own historical logic.