Why is reason predisposed to metaphysical, dialectical inferences? In order to strengthen morality, reason has a tendency to be unsatisfied with physical explanations that relate only to nature and the sensible world. Reason uses Ideas that are beyond the sensible world as analogies of sensible objects. The psychological Idea of the Soul is a deterrent from materialism. The cosmological Ideas of freedom and natural necessity, as well as the magnitude and duration of the world, serve to oppose naturalism, which asserts that mere physical explanations are sufficient. The theological Idea of God frees reason from fatalism.