Our senses do not take in the world as it is. Rather the mind construes an intelligible world for human and personal purposes. What remains of reason, truth and knowledge when this post-modern insight is accepted? This book draws a sharp distinction between responsible pluralism and anything-goes relativism, arguing that Nietzsche and his followers are correct that all cognition depends on willful acts of interpretation, but wrong in concluding that discourse between interpretive cultures can be nothing more than a power struggle. It responds to the post-modern "scandal of interpretations" by showing how public truth may be construed, and deployed in policy making, as a structure of argument among conflicting strategies of understanding.