Generalgleichgewichtmodelle

Generalgleichgewichtmodelle describe the balance of an economy with many markets simultaneously. In these models, markets for goods and services, and often financial instruments, are interlinked through the actions of households and firms. Households maximize utility subject to budget constraints, while firms maximize profits given production technologies and factor supplies. Prices act as signals, and a general equilibrium occurs when supply equals demand in every market.

In Arrow-Debreu formulations, markets for contingent commodities across all future states are typically assumed complete, allowing a unified treatment of intertemporal and uncertain outcomes. This framework enables a rigorous analysis of how prices coordinate intertemporal decisions and risk allocation.

Core elements include: a set of commodities (often including time and state contingencies), a population of agents with preferences and endowments, and production sets. The model seeks price vectors and quantity allocations that satisfy budget constraints, feasibility, and market-clearing conditions across all markets.

Existence and welfare results are central. Under suitable conditions (continuity, convexity, monotonicity, and closed production/consumption sets), existence theorems guarantee a price vector that clears all markets. The First Welfare Theorem states that any competitive general equilibrium is Pareto efficient, while the Second Welfare Theorem shows that any Pareto-efficient allocation can be decentralised by appropriate transfers and prices, given convexity. Limitations arise with non-convexities, externalities, incomplete markets, or public goods, where standard results may fail or require refinements.

Dynamic extensions, such as dynamic stochastic general equilibrium (DSGE) models, incorporate time and uncertainty, and are widely used in macroeconomics and policy analysis. Generalgleichgewichtmodelle thus provide a foundational framework for understanding how a whole economy coordinates across markets under competition.