pt. 1. The Walrasian system. The neoclassical theory of the consumer -- The neoclassical theory of production -- General equilibrium in a barter economy -- Introducing prices : perfect competition and Pareto efficiency -- Market failure and the second fundamental theorem of welfare economics -- pt. 2. Modern welfare economics. The theoretical critique of Walrasian welfare economics -- The behavioral critique of Walrasian welfare economics -- Cost-benefit analysis old and new -- The future of economic theory and policy.