Microeconomics
Microeconomics studies how individual decision-makers — households, firms, and other agents — make choices under scarcity, and how their interactions in markets determine the prices and allocation of goods, services, and resources. It provides the analytical foundations on which much of modern economics is built, from the theory of demand and supply to strategic interaction and the analysis of market failure.
Scope
The field analyses the optimizing behaviour of consumers and producers, the formation of prices in different market structures (competition, monopoly, oligopoly), the conditions under which markets allocate resources efficiently, and the ways in which they fail to (externalities, public goods, asymmetric information, market power). It encompasses consumer and producer theory, general equilibrium analysis, welfare economics, game theory and the economics of information, and increasingly the behavioural foundations of choice. In JEL terms it corresponds to category D and its subcategories (D1–D9).
Sub-topics
Core questions
- How do households and firms make optimal choices subject to constraints?
- How are prices determined under different market structures?
- Under what conditions does a competitive market allocate resources efficiently, and when does it fail?
- How do agents behave strategically when their payoffs depend on one another's choices?
- How do imperfect information and bounded rationality change market outcomes?
Key concepts
- Utility maximization and demand
- Profit maximization and supply
- Marginal analysis
- Market structure (competition, monopoly, oligopoly)
- General equilibrium
- Pareto efficiency and the welfare theorems
- Externalities and public goods
- Asymmetric information (adverse selection, moral hazard)
- Nash equilibrium
- Bounded rationality
Key theories
- Consumer and producer theory (marginalism)
- Building on the marginal revolution, individual demand and supply are derived from constrained optimization — utility maximization by consumers and profit maximization by firms — with comparative statics making the framework operational.
- General equilibrium theory
- Walras posed the problem of simultaneous equilibrium across all markets; Arrow, Debreu, and McKenzie later proved, under convexity assumptions, the existence of a competitive equilibrium and clarified its efficiency properties.
- Game theory and strategic interaction
- Von Neumann and Morgenstern founded the formal theory of games; Nash's equilibrium concept generalized analysis to non-cooperative settings where each agent best-responds to others, becoming the workhorse of modern microeconomics.
- Welfare economics and market failure
- The welfare theorems link competitive equilibria to Pareto efficiency; Coase showed how property rights and transaction costs shape the efficient handling of externalities, framing much of the analysis of market failure.
- Economics of information
- Akerlof showed that asymmetric information about quality can unravel a market entirely ('lemons'), launching the analysis of adverse selection, signalling, and screening.
- Behavioural foundations of choice
- Kahneman and Tversky's prospect theory documented systematic departures from expected-utility maximization, providing a descriptive alternative that reshaped micro-based behavioural economics (JEL D9).
History
Microeconomics took its modern shape with the marginal revolution of the 1870s (Jevons, Menger, Walras), which recast value in terms of marginal utility and constrained optimization. Marshall synthesized demand and supply into partial-equilibrium analysis, while Walras formulated general equilibrium. Samuelson's Foundations (1947) gave the field a unified mathematical method, and Arrow, Debreu, and McKenzie placed general equilibrium on rigorous axiomatic ground in the 1950s. From the 1940s, game theory (von Neumann–Morgenstern, Nash) provided tools for strategic interaction; from the 1960s–1970s, the economics of externalities (Coase) and of information (Akerlof, Spence, Stiglitz) extended analysis to market failure; and from the late 1970s, behavioural work (Kahneman–Tversky) challenged the rational-choice core that still organizes the field.
Debates
- How realistic is the rational-choice/expected-utility model?
- Standard theory assumes optimizing agents with stable, consistent preferences. Behavioural economics, grounded in documented anomalies, argues for psychologically richer models; defenders maintain the standard model's predictive parsimony and 'as-if' justification.
- What does general equilibrium theory actually explain?
- The Arrow–Debreu model proves existence and efficiency under strong assumptions; critics question its descriptive relevance and stability, while proponents value it as a rigorous benchmark for when markets do and do not allocate efficiently.
Key figures
- Léon Walras
- Alfred Marshall
- John von Neumann
- Oskar Morgenstern
- Paul Samuelson
- Kenneth Arrow
- Gérard Debreu
- John Nash
- Ronald Coase
- George Akerlof
- Daniel Kahneman
- Amos Tversky
Related topics
Seminal works
- walras-1874
- marshall-1890
- von-neumann-morgenstern-1944
- arrow-debreu-1954
- coase-1960
- akerlof-1970
- kahneman-tversky-1979
Frequently asked questions
- How does microeconomics differ from macroeconomics?
- Microeconomics studies individual agents and specific markets and how they interact; macroeconomics studies economy-wide aggregates such as output, inflation, and unemployment. Modern macroeconomics is, however, largely built on microeconomic foundations.
- Is game theory part of microeconomics?
- Yes. Game theory is the standard toolkit for analysing strategic interaction within microeconomics, and in the JEL scheme it sits in category C (methods) and D (microeconomics) depending on emphasis.