 Kant defines primacy as “the prerogative of the interest of one insofar as the interests of others is subordinated to it” (5:119). He gives two reasons for thinking that practical reason has this  “prerogative.”[18]  First, practical reason can be “pure” or independent from “pathological conditions,” that is, our inclinations. So it is not conditioned by anything else—for instance, by a desire for happiness or subjective wishes. In other words, (pure) practical reason is independent from our inclinations. By contrast, theoretical reason falls into error if it claims independence from the deliverances of sensibility and understanding—for example, in attempting to prove the existence of God. Second, Kant argues that we cannot leave the question of primacy undecided, because practical reason would otherwise come into conflict with theoretical reason. The interest of theoretical reason consists in expanding our knowledge and avoiding error—which means suspending all claims to knowledge beyond the bounds of experience. However, insofar as theoretical reason has interests at all, this is itself a practical matter, “since all interest is ultimately practical.” So Kant writes: