Book excerpt: Now available in paperback A Contribution to the Pure Theory of Taxation investigates the way in which tax systems affect economic efficiency and the distribution of welfare. 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.