  Just as Kant held that chemistry could either be scientific in less than the strictest sense or perhaps become science proper (depending on how it develops), the same could be said for psychology. For one, Kant may simply be objecting to psychology as it was practiced in the 18th century, e.g., as based on introspection (a method that both rules out the application of mathematics and gives rise to other difficulties, 4:471). Further, in the Critique of Pure Reason, Kant holds that although objects can never be given in intuition that would correspond to ideas of reason, such ideas never the less function as regulative principles that direct our understanding with regard to what it should inquire into next. Thus, our idea of the world as a totality is supposed to drive us to look for smaller and smaller parts to bodies and objects in further regions of space and at earlier moments of time.  But if we have an idea of our soul, then it too should guide our scientific inquiry into our own representations, which seems to imply that psychology is a legitimate scientific practice (even if it does ultimately fall short of being science proper).