When studying the relation of Kant's practical philosophy to the theoretical, one tends to stress either a set of structural analogies and similarities or the material way in which Kant supposes the two domains to complement one another. My own approach in this paper will be to link them programmatically, from the standpoint of Kant's philosophical program and the "interests of reason" which are said to underlie it. This, for Kant, is the standpoint of the "architectonic of reason," the meta-philosophical theory which refers to reason as a system of ends or rational interests, and explicates the way in which these ends are to co-exist and be harmonized in the pure system of reason — that is, in the thought and action of rationally-enlightened humans. As a by-product it also explains the conflicting and impure modes in which these rational interests are manifest historically in the course of reason's self-evolution and before its pure system has been fully and coherently brought to light.¹