The article describes the role of the mathematische Psychologie in the German philosophical discourse of the 19th – early 20th centuries. The history of mathematical psychology is viewed from the standpoint of the disciplinary approach in historiography. The author focuses on the reconstruction of social mechanisms that determine the content of the discipline, its relationship with the structure and specifics of the functioning of universities and academic institutions, as well as academic corporations. The author shows that several times mathematical psychology had been in the center of disciplinary conflicts. At first, it was a subject of controversy between the Herbartarians and the Neo-Kantians. After the publication of Fechner’s Elements of Psychophysics, academic philosophers perceived physiological psychology as "mathematical psychology". By the end of the 19th century, after the heyday of psychophysics, during the rise of a new wave of Neo-Kantianism, the psychology of Herbart and psychophysics became the subject of a polemic between Dilthey and Ebbinghaus about the revision of the methodological bases of psychology. The discussion of the early 20th century on the exclusion of experimental psychology from the list of philosophical disciplines completes the process of turning to mathematical psychology as an argument for defining the disciplinary boundaries. The history of mathematische Psychologie showed that even when it was only a question of mathematics as a method, real battles took place in philosophical disciplines, in which representatives of different methodological camps tried to defend their independence. Started as a philosophical argument, the debate on the mathematische Psychologie gradually turned into a branding of the methodologically backward and outdated.