Click on the phrases to see them in context. The original texts by Immanuel Kant and David Hume are available from the Gutenberg Projet.

Thus applied logic treats of attention, its impediments and consequences, of the origin of error, of the state of doubt, hesitation, conviction, etc., and to it is related pure general logic in the same way that pure morality, which contains only the necessary moral laws of a free will, is related to practical ethics, which considers these laws under all the impediments of feelings, inclinations, and passions to which men are more or less subjected, and which never can furnish us with a true and demonstrated science, because it, as well as applied logic, requires empirical and psychological principles.