The second of Kant's three critiques, Critique of Practical Reason forms the center of Kantian philosophy; published in 1788, it is bookended by his Critique of Pure Reason and Critique of Judgement. With this work Kant establishes his role as a vindicator of the truth of Christianity; he approaches his proof by presenting positive affirmation of the immortality of the soul and the existence of God. The philosopher offers an argument concerning the summum bonum of life: people should not simply search after happiness, but follow the moral law and seek to become...