In light of this distinction, one can better understand the significance of the debate on psychologism such as Stumpf describes it in his 1891 paper. Stumpf opposes two schools of thought on the question of the relationship between the theory of knowledge and psychology: Kantian criticism that dissociates the theory of knowledge from psychology, and psychologism which Stumpf defines in this paper as “the reduction of all philosophical investigation, and especially all epistemological investigati