Now available in paperback this book investigates the way in which tax systems affect economic efficiency and the distribution of welfare. It examines within a unified framework questions that are usually treated in different areas of the literature: institutional economics, positive economics, normative economics, and political economics. It adheres to the rigorous standards of pure theory while paying careful attention to the policy relevance of the arguments. Tax systems are viewed as information extracting devices that generate sets of equilibria of complex geometry. A tax reform methodology is proposed that sheds light on optimal taxes. Social conflicts in the determination of taxes are shown to have effects on social cohesion.