Generalgleichgewichtsmodell

Generalgleichgewicht, or general equilibrium, is a framework in economics for analyzing how supply and demand across multiple interrelated markets determine prices and allocations in an economy. In this framework, agents possess initial endowments of goods and trade in a set of commodities. Prices adjust so that, at equilibrium, the quantity supplied equals the quantity demanded for every good.

Formally, a Walrasian equilibrium consists of a price vector p* and an allocation x* such that each agent, given prices, chooses a best affordable bundle, and markets clear: sum of demand equals sum of endowments for each good. The Arrow–Debreu model extends this to a general equilibrium with complete markets, convex preferences, and continuity; under standard regularity conditions, a general equilibrium exists.

Key results include the First Welfare Theorem, which states that a competitive equilibrium is Pareto efficient, and the Second Welfare Theorem, which shows that any Pareto efficient allocation can be supported as a competitive equilibrium with appropriate redistribution of endowments and prices.

Dynamic processes such as tâtonnement describe how prices might adjust toward equilibrium in theory, without actual trade during adjustment. In practice, markets may fail to converge due to non-convexities, externalities, incomplete markets, public goods, or frictions.

General equilibrium differs from partial equilibrium by treating all markets simultaneously rather than in isolation. It forms the basis of computable general equilibrium (CGE) models used in policy analysis, as well as some micro-founded macro models.

Historically, the concept originated with Léon Walras in the 19th century and was formalized in the Arrow–Debreu framework in the 1950s.