This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Kant's ethics rests on a single test he called the categorical imperative, set out most fully in the 1785 Groundwork of the Metaphysics of Morals: act only according to a rule you could, at the same time, will to become a universal law binding on everyone, without contradiction. A lie, on this test, fails not because of its consequences but because a world in which everyone lied whenever convenient would make the very practice of promising or asserting anything meaningless, so the rule cannot be consistently universalized. Moral worth, on Kant's account, belongs only to actions done from duty to that self given law, autonomy, rather than actions merely aligned with duty by inclination, fear, or self interest.
Kant extended the same rational framework to religion in 1793 with Religion Within the Boundaries of Mere Reason, arguing Christian doctrine could be reinterpreted as pointing toward the same rational moral law rather than resting on revelation or church authority. Prussia's religious censor under Frederick William II judged the book an abuse of philosophy to distort core Christian teaching, and in 1794 the king personally ordered Kant, by then in his seventies, to cease publishing or lecturing on religious subjects entirely.
Kant complied for the remainder of Frederick William's reign, a rare instance of the philosopher of universal reason and autonomy submitting, by his own account as a loyal subject, to a royal command he privately still judged unjust.