General Equilibrium

General equilibrium is the macroeconomic condition in which all markets in an economy simultaneously clear — supply equals demand not merely in a single market but across all interconnected markets at once. The concept was formalized by Léon Walras and later refined by Kenneth Arrow and Gérard Debreu, who proved that under stringent assumptions (convex preferences, complete markets, no externalities), such an equilibrium exists and is Pareto efficient.

The first welfare theorem is the formal expression of the invisible hand: competitive equilibrium is Pareto-optimal. The second welfare theorem states that any Pareto-optimal allocation can be decentralized through competitive markets plus lump-sum transfers. Both theorems are existence proofs, not guarantees. The assumptions they require are violated in virtually every real economy, which is why general equilibrium theory is better understood as a boundary condition than a description.

General equilibrium is closely related to computable general equilibrium models used in policy analysis, though the gap between theoretical existence and computational tractability remains vast.