In the interwar period a noticeable pluralism of pedagogical theories was characteristic for Slovenia. In the world as well as in Slovenia we can find representatives of the reform pedagogy (a concept which gave children prominence), cultural pedagogy (a concept that gave prominence to the teacher’s sensibility for culture) and socially critical pedagogy (a concept that gave prominence to the teacher’s sensibility for social fairness). The article presents the contents of two polemics in which Anton Osterc, a teacher at the burgher school in Maribor and the principal at the burgher school in Monfalcone untill World War II, participated. Osterc was one of the few typical representatives of reform pedagogy in Slovenia. His polemic about the old and the new school, that he had with dr. Karl Ozvald, a professor at the University of Ljubljana and a characteristic representative of cultural pedagogy, is famous. In the second polemic Osterc was defending the position of reform pedagogy against socially critical pedagogy. The second actor in this controversy was the Serbian teacher Dragutin Mihailović, who was Marxist-oriented. Due to the nature of a polemic the theoretical as well as ideological and political differences between actors are particularly focused and therefore also very explicit.