This dissertation examines Kant's project in his Metaphysical Foundations of Natural Science to present a `critically' approved account of physical entities, purportedly necessary for all scientific investigation. It develops an original interpretation of its key programmatic premises, which revolve around the attribution of motion to matter as a way of making further a priori claims about outer things in general. It clarifies the connections these premises have to central doctrines of the Critique of Pure Reason such as Kant's theories about mathematical cognition and the constitution of perception according to sensation. Fatal flaws in Kant's project, however, compel revisions that affect those very doctrines that were supposed to provide a prior basis for it. The dissertation outlines these problems and the corresponding revisions with the help of Hegel's surprisingly sympathetic and detailed criticisms of Kant's Metaphysical Foundations. This has the added benefit of showing how Hegel's own philosophical approach is much more intimately informed by Kant's said project than it initially appears. In sum, Kant is asked to relinquish his transcendental-psychological framework in favor of an account of perception which is immanently reflective and which rests on rational-physical bases instead of providing an allegedly subjectivist basis for the latter. This result issues a challenge for us to think such revisions without helping oneself either to a blatant Hegelian rationalism or an anachronistic naturalism foreign to Kant.