From anthropology to rational psychology in Kant’s Lectures on Metaphysics

If one were to ask a specialist what Kant thought about rational psychology, their first point of reference would undoubtedly be to Kant’s well-known charges against this type of dogmatic reasoning in the Paralogisms section of the Critique of Pure Reason. Having spent the first half of the Critique on a description of the manner by which general metaphysics or “the proud name of Ontology” must give way to a mere analysis of the understanding (A247/ B304), Kant had been determined in the second half of the Critique to expose the illusions at work in the “special” metaphysics devoted to topics such as cosmology, the immortal soul or the existence of God. In the case of rational psychology, its doctrines regarding the soul were ultimately taken by Kant to be the result of a simple misunderstanding (B421). Namely, its practitioners, among whom Descartes certainly counted as themost famous, had mistaken a bare sense of the “I think” – a sense responsible for our indexing the I to the unity, constancy and indeed recognizability of one’s inner and outer perceptions – for the whole person, i.e. for not only the person of our constant inner experience, the person whose thoughts, memories and dreams defined us, but for the intelligible person of our moral life, the character whose choices bore the imprint of our immortal soul (B422, n.). This did not mean that there was no place for the latter considerations; on the contrary, Kant was clear regarding our rational need to believe in the soul, and on the practical benefits conveyed by humankind’s concern for it. Rational psychology, as he put it, prevents us “from throwing ourselves into the arms of a soulless materialism,” even if it fails to provide any actual knowledge or practical doctrines regarding the soul (B421). These positive results could emerge, however, only after the practitioners of rational psychology were ready to give up their “windy hypotheses of the generation, extinction, and palingenesis of souls” (A683/B711), and redirect their efforts instead to outlining the practical employment of their ideas in the moral sphere, since it was in this sphere alone that such ideas could “regulate our actions as if our destiny reached infinitely far beyond experience, therefore far beyond our present life” (B421; cf. GMS, 5:461).