Metaphysics, as a natural disposition of reason, is actual. Yet metaphysics itself leads to illusion and dialectical argument. In order for metaphysics to become a science, a critique of pure reason must systematically investigate the role of "a priori" concepts in understanding. The mere analysis of these concepts does nothing to advance metaphysics as a science. A critique is needed that will show how these concepts relate to sensibility, understanding, and reason. A complete table must be provided, as well as an explanation of how they result in synthetic "a priori" knowledge. This critique must strictly demarcate the bounds of reason. Reliance on common sense or statements about probability will not lead to a scientific metaphysics. Only a critique of pure reason can show how reason investigates itself and can be the foundation of metaphysics as a complete, universal, and certain science.