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L12. General Equilibrium. Review. Model of choice of individual We know preferences and we find demands With many such agents: Q1: How prices are formed? Q2: Are markets efficient?. “Economy” with apples and oranges. Two consumers, A and B.
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L12 General Equilibrium
Review • Model of choice of individual • We know preferences and we find demands • With many such agents: • Q1: How prices are formed? • Q2: Are markets efficient?
“Economy” with apples and oranges • Two consumers, A and B. • Total resources available • Feasible allocation and
Geometric representation • Four numbers and geometric representation • Insane? • No: Edgeworth box • Collection of all feasible allocations
OB Edgeworth Box OA
Desirable Allocation: Pareto Efficient • When allocation is “socially” efficient? - Maximizing sum of utilities? NO! - Weaker notion: Pareto efficiency! • 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
OB Pareto Efficiency OA
OB Pareto Efficiency=Tangenency OA
OB Contract Curve • The contract curve is the set of all Pareto-optimal allocations. OA
OB Contract Curve • The contract curve is the set of all Pareto-optimal allocations. OA
How do Markets Work? How do markets work? • Individuals respond optimally to prices • Prices are such that markets clear We call a competitive equilibrium
Excess supply, Demand OB OA
Invisible Hand OB • Are markets (Pareto) efficient? • First Welfare Theorem: allocation in Competitive equilibrium is Pareto optimal • Proof OA