A central doctrine of Kant's Critique of Pure Reason holds that the content of human experience is rooted in an affection of sensibility by unknowable things in themselves. This famous and puzzling affection doctrine raises two seemingly intractable old problems, which can be termed the Indispensability and the Consistency Problems. By what right does Kant present affection by supersensible entities as an indispensable requirement of experience? And how could any argument for such indispensability avoid violating the Critique's doctrine of noumenal (...) ignorance? This essay develops a new solution to both problems, setting out from the continuity between Kant's early and mature views on sensibility and mind-world relations. Kant's early writings subscribe to an interactionist cosmology opposed to both Leibniz's preestablished harmony and Malebranche's occasionalism. The modern debate on mind-world relations shaping Kant's early cosmology points us to a widely recognized motivation for interactionism, turning on a constraint on agency within certain noninteractionist cosmologies. In particular, Kant's early conversion to a libertarian theory of freedom, together with his rejection of occasionalism, provides the basis for a compelling argument for the indispensability of world-mind affection relations. Extended to the transcendental idealist framework, the same argument reveals noumenal affection as an indispensable presupposition of some knowledge claims consistently upheld by Kant. This leads in turn to a satisfying solution to the Consistency Problem, showing that the doctrine of noumenal affection is not merely consistent with, but is partly motivated by, Kant's commitment to noumenal ignorance. (shrink)