a priori categories from self-observation, and Hermann Helmholtz traced the origin of concepts, numbers and classes to psychological, and even to physiological processes.¹ John Stuart Mill was often cited by these and later psychologistic authors as their most illustrious ally, because he claimed that philosophy's principal task is to conduct empirical inquiry into the workings of the mind, and explicitly described introspection as the only basis on which the axioms of mathematics and the principles of logic might be justified.²" /> Psychologism and logical analysis - Cobb-Stevens Richard | sdvig press