In the doctrine of self-positing Kant provides both a logical structure for and a genetic account of the subject knower's insertion into a natural world that is simultaneously of its own making. These correspond to two levels to this doctrine of self-positing, the first is analytical and the second is ontological. It is within the latter that Kant develops the notion of an"act of receptivity" that expands upon his earlier critical thought on the roles of the faculty of sensibility and embodiment of the subject knower. In this way, the doctrine of self-positing provides us with a clearer understanding of the nature of the finite empirical subject and its relationship to its universal counterpart. I show this by introducing the concept of"fields of determinability" that are necessary for any positing to take place at all, while at the same time exposing the vulnerability of the Kantian subject as both the cause and bearer of conditions upon which it has little or no control. These developments it is possible to conceptialize an opening of an epistemological field proper to philosophical anthropology. The dissertation is composed of four sections. The first provides an analysis of the concept of positing in Kant's theoretical philosophy. The second contextualizes the doctrine of self-positing within the Opus postumum as a whole, introduces the systematic location of the doctrine and situates its problematic historically. The third part examines the"analytic level" of the doctrine. And the fourth brings the former sections to bear upon the reconstruction of Kant's doctrine of self-positing, especially with regards to receptivity.