A depraved conscience -- not merely ignorant but willfully corrupt -- is the most destructive force in political life. In an incisive reflection on politics and original sin, a relentlessly perceptive political philosopher demonstrates that modern ideologies all deny the fallen nature that is source of the three great problems of public life: we do wrong, our thinking about the wrong we do is clouded, and our efforts to rectify that wrong are themselves deformed by sin. Blinded to this truth about ourselves, we habitually suppress our conscience until it is corrupted, and, taking its revenge, leads us to cultural calamity.