 Kant held that ordinary moral thought recognized moral duties toward ourselves as well as toward others. Hence, together with the distinction between perfect and imperfect duties, Kant recognized four categories of duties: perfect duties toward ourselves, perfect duties toward others, imperfect duties toward ourselves and imperfect duties toward others. Kant uses four examples in the Groundwork, one of each kind of duty, to demonstrate that every kind of duty can be derived from the CI, and hence to bolster his case that the CI is indeed the fundamental principle of morality. To refrain from suicide is a perfect duty toward oneself; to refrain from making promises you have no intention of keeping is a perfect duty toward others; to develop one’s talents is an imperfect duty toward oneself; and to contribute to the happiness of others is an imperfect duty toward others. Again, Kant’s interpreters differ over exactly how to reconstruct the derivation of these duties. We will briefly sketch one way of doing so for the perfect duty to others to refrain from lying promises and the imperfect duty to ourselves to develop talents.