Reading Immanuel Kant’s Critique of Pure Reason, it is easy to conclude that Kant had no sense of psychology as a separate scientific discipline. In fact, he was very clear that it had to be removed from metaphysics. But on the other hand, his last thesis was Anthropology from a Pragmatic Point of View. This was his original contribution to psychology. The challenge, however, was that he had problems with the term “psychology.” The far more decisive factor, however, was the prehistory of psychology, having been incorporated into metaphysics by Christian Wolff earlier in the eighteenth century. This chapter takes as its starting point the prehistory of this close connection between philosophy and psychology in order to examine more closely why Kant speaks so disapprovingly of psychology. The methodological approach to this is a classic hermeneutic spiral, in which his Critique of Pure Reason forms the textual starting point, but whereas his other critiques, his lectures on metaphysics, and psychology, and not the least his treatise on anthropology, form the supplementary and elaborating texts. The findings presented in this chapter show first and foremost that Kant not only had a close relationship with psychology throughout this critical period, but that he also constructed a psychological model of thinking that forms the basis of his theory of cognition. In brief, this model consists of the elements of sensation, intuition, representation, reflection, understanding, and reason. Kant constructed this model on the basis of his need to uncover the mental capabilities needed to show that human beings actually have the prerequisites for arriving at valid philosophical conclusions, namely the 12 categories of understanding. The latter are not of interest to psychology but are crucial to ontology and thus philosophy. These categories of understanding were important to Kant, which is why he aimed to create a sharp distinction between psychology and philosophy, despite basing his entire reasoning on a psychological model of thinking.