Abstract

In this essay, I examine the motive of inner truthfulness in the moral philosophy of Kant, which came to the fore in his work in the 1790s. Truthfulness and sincerity are interpreted as the roots of all morality. In the first chapter, I present two interpretations of inner honesty from two different perspectives: in relation to a duty to oneself and to the issue of conscience. The second chapter (the core of the essay) works out the main demand of truthfulness, especially in the context of the theory of radical evil from Religion within the Boundaries of Mere Reason. As a last step, I show that with the motive of truthfulness, Kant’s philosophy meets the thinking of F. Nietzsche, with its emphasis on sincerity.