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Delve into the concepts of Pareto efficiency, Walrasian equilibrium, and the First Welfare Theorem in economics. Explore the principles of market efficiency and individual optimization.
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L13 General Equilibrium (cont)
Big ideas: Tuesday: • Edgeworth box • Pareto efficiency (normative theory) Today: • Competitive equilibrium (positive theory) • First welfare theorem
OB Edgeworth Box OA
Desirable Allocation: Pareto Efficient • Allocation x Pareto efficient, if there does not exist allocation y that is A) at least as good as x for all B) is strictly better for at least one • Pareto efficiency = equality of MRS • All Pareto efficient allocations=contract curve
OB Pareto efficiency OA
Competitive (Walrasian) Equilibrium • Competitive Equilibrium • A positive model of • free market economy • “selfish” consumers • Walras, then Arrow and Debreu • Extensively used by ``practitioners’’
Competitive (Walrasian) Equilibrium Consider • Individuals respond optimally to prices • Prices are such that markets clear We call a competitive equilibrium
Excess supply, Demand OB OA
Cobb-Douglass Calculation • Equilibrium = 6 numbers • Existence, uniqueness • 3 tricks that simplify calculation • Market clearing for one market (Walras Law) • Use Magic Formulas • Solve for relative price (only)
OB Geometry OA
Invisible Hand (Adam Smith) OB • Are markets (Pareto) efficient? OA
Invisible Hand (Adam Smith) First Welfare Theorem: allocation in Competitive equilibrium is Pareto optimal Proof: Intuition