Together with other influential psychologists of the time, Wundt considers internal data as absolute evidence, grounding psychology on this assumption. In opposition to his former mentor, Külpe aims at rehabilitating Kant’s transcendental aesthetics. Yet, he is far from embracing transcendentalism and rejects Kant’s skepticism as to the possibility of a scientific psychology. Nevertheless, Külpe believes that Kant is right in considering internal data as unreliable for scientific purposes: accordingly, psychology should share the same scientific methodology of any other science.