Preistheorie

Preistheorie, or price theory, is a branch of economics that analyzes how prices arise from the interaction of supply and demand and how those prices coordinate the use of scarce resources. It rests on assumptions of rational decision-making, optimization by agents, and the operation of markets, while also studying deviations from perfect competition and other real-world frictions.

The core mechanism is the price system: demand curves reflect the marginal benefits to consumers, and supply curves reflect the marginal costs to producers. The market price tends toward an equilibrium where quantity supplied equals quantity demanded. Elasticity measures how responsive quantity demanded or supplied is to price changes, and marginal analysis examines decisions at the margin, such as comparing marginal cost and marginal revenue.

Market structure matters for price formation. In perfectly competitive markets, prices tend toward marginal cost and resources are allocated efficiently. In markets with some degree of market power, such as monopolies or oligopolies, prices can exceed marginal cost, leading to allocations that may be less efficient.

Prices respond to a range of factors that shift supply and demand, including income, tastes, prices of related goods, expectations, technology, and input costs. Price changes convey information and provide incentives that direct resources toward higher-valued uses. Welfare analysis uses concepts like consumer surplus, producer surplus, and deadweight loss to assess efficiency.

Applications and limitations: price theory informs pricing strategies, auction design, and theories of discrimination, as well as regulatory and tax policy. Its predictive power depends on its assumptions; real markets exhibit frictions such as information asymmetries, externalities, public goods, and transaction costs, which can limit the applicability of simple price-based explanations.