Economics

Micro and macro concepts, schools of thought, and key economists.

A study reference, not a substitute for primary sources. Updated 2026-09-08.

Core Microeconomics

Supply and demand — the core model: quantity supplied rises with price; quantity demanded falls with price. Equilibrium is where supply and demand curves intersect.
Scarcity and opportunity cost — limited resources force choices among competing uses. The opportunity cost of a choice is the value of the best alternative forgone, including uses of time as well as money. Marginal analysis compares the additional benefit and additional cost of a small change; sunk costs are already irrecoverable.¹
Consumer surplus / producer surplus — consumer surplus: the difference between willingness-to-pay and market price; producer surplus: the difference between market price and minimum willingness-to-sell. Together they compose total welfare.
Price ceiling / price floor — a ceiling (set below equilibrium) causes shortages; a floor (set above equilibrium) causes surpluses. Classic examples: rent control (ceiling), minimum wage (floor).

Elasticity of demand — percentage change in quantity demanded divided by percentage change in price. Demand is elastic when

> 1, inelastic when

< 1, and unit elastic when

= 1. Along a demand curve, a price rise reduces revenue in the elastic region and increases it in the inelastic region; unit elasticity gives no first-order revenue change. Revenue maximization is distinct from profit maximization.²

Income elasticity — positive for normal goods; negative for inferior goods (e.g., bus travel for high-income consumers). Luxury goods have income elasticity > 1.
Cross-price elasticity — positive for substitutes; negative for complements.
Marginal utility — additional utility from consuming one more unit; diminishing marginal utility is the standard assumption. Rational consumers equalize marginal utility per dollar across goods.
Indifference curves — combinations of two goods giving equal utility; convex to the origin. Budget constraint defines affordable combinations; utility-maximizing choice is at the tangency.
Giffen good — a (rare) inferior good whose demand rises when its price rises, because the negative income effect dominates the substitution effect.
Veblen good — demand rises with price due to status signaling; not Giffen (different mechanism).
Edgeworth box — a diagram placing two consumers’ (or countries’) indifference curves in a shared rectangular space; the contract curve traces all Pareto-efficient allocations within it; developed by Francis Ysidro Edgeworth.
Pareto efficiency (Pareto optimum) — an allocation is Pareto efficient if no reallocation can make any agent better off without making at least one worse off; a minimal welfare standard, not an equity criterion.
Revealed preference — Paul Samuelson’s approach: infer consumer preferences from observed choices rather than introspective utility; foundational to modern demand theory.
Substitution effect vs income effect — a price change has two components: a substitution effect (relative price shift) and an income effect (change in real purchasing power); their interaction determines the slope of demand curves and distinguishes normal from inferior and Giffen goods.

Production and Costs

Production function — relates inputs (labor, capital) to output. Marginal product of labor (MPL) diminishes as labor is added to fixed capital (short run).
Short run vs long run — in the short run, at least one input (usually capital) is fixed. In the long run, all inputs are variable.
Fixed cost / variable cost / total cost — average total cost (ATC) = TC / Q; marginal cost (MC) = dTC/dQ. A firm produces where MC = MR.
Economies of scale — ATC falls as output grows (increasing returns to scale). Diseconomies of scale: ATC rises.
Sunk cost — an already-incurred, irrecoverable cost; should not influence forward-looking decisions (though behaviorally it often does).
Shutdown rule — in the short run, a firm shuts down if price < AVC; in the long run, exits if price < ATC.
Lemons problem — George Akerlof’s 1970 model: in a used-car market, sellers know quality but buyers don’t; adverse selection can collapse markets entirely when only “lemons” (low-quality goods) remain; foundational to information economics.
Signaling (Spence) — Michael Spence: high-type workers obtain costly credentials (education) to credibly signal unobservable quality to employers, even if the credential adds no productive skill.
Principal-agent problem — the agent (employee, manager) has different interests and private information compared to the principal (employer, shareholder); mitigated by incentive contracts, monitoring, and bonding.
Price discrimination — first degree: charge each consumer their exact willingness to pay. Second degree: quantity discounts, versioning. Third degree: different prices to different market segments (e.g., student discounts).

Market Structures

Structure	Sellers	Price control	Profit (long run)	Example
Perfect competition	Many	Price taker	Zero (entry/exit)	Wheat farming
Monopolistic competition	Many	Some	Zero (entry/exit)	Restaurants
Oligopoly	Few	Interdependent	Positive (barriers)	Airlines, mobile carriers
Monopoly	One	Price maker	Positive (barriers)	Utility with exclusive franchise

Perfect competition — homogeneous product, free entry/exit, perfect information. Equilibrium: P = MC = ATC (long run).
Duopoly — a market structure in which exactly two sellers (or buyers, in a duopsony) dominate the market; a special case of oligopoly; analyzed using Cournot, Bertrand, and Stackelberg models; real-world examples include commercial aircraft (Airbus/Boeing) and some regional telecommunications markets.
Monopoly — sets MR = MC, then charges the demand curve price; produces less at higher price than competitive market. Deadweight loss quantifies inefficiency.
Natural monopoly — ATC declines over the entire relevant output range; a single firm serves the market more cheaply than multiple firms. Regulated via average-cost pricing or marginal-cost pricing.
Oligopoly — strategic interdependence; analyzed with game theory. Models include Cournot (quantity competition), Bertrand (price competition), and Stackelberg (sequential leadership).
Monopolistic competition — many firms sell differentiated products; entry drives economic profit to zero; firms operate on the downward-sloping part of ATC (excess capacity).

Game Theory

Prisoner’s dilemma — two players each have a dominant strategy that leads to a mutually worse outcome than cooperation. The Nash equilibrium is (defect, defect).
Nash equilibrium — a strategy profile in which no player can improve their payoff by unilaterally changing strategy. Named for John Nash; formalized 1950.
Dominant strategy — a strategy that is best regardless of the other player’s action.
Repeated games — repeated interaction can sustain cooperation that a one-shot game cannot; tit-for-tat is a notable cooperative strategy in iterated prisoner’s dilemmas (Axelrod tournaments).
Coordination game — players prefer to choose the same strategy; multiple Nash equilibria possible. Example: driving on the left vs right.
Moral hazard — a party takes greater risks because someone else bears the cost (e.g., insured driver; bailed-out bank).
Adverse selection — before a transaction, one party has private information leading to a skewed pool (e.g., “lemons” in used-car markets; Akerlof 1970).
Arrow impossibility theorem — Kenneth Arrow (1951): no ranked voting system can simultaneously satisfy unanimity, independence of irrelevant alternatives, and non-dictatorship when there are three or more options; foundational result in social choice theory.
Minimax theorem — John von Neumann (1928): in zero-sum two-player games, the strategy that minimizes the maximum loss (minimax) equals the strategy that maximizes the minimum gain (maximin); foundational result of game theory.
Backward induction — in extensive-form games, solving from the last move backward to determine the subgame perfect Nash equilibrium; central to sequential game analysis.
Auction theory — studies optimal bidding and auction design; key results include the revenue equivalence theorem (standard auctions yield equal expected revenue under symmetric conditions); associated with William Vickrey and Roger Myerson.
Vickrey auction (second-price sealed-bid) — bidders submit sealed bids; the highest bidder wins but pays the second-highest bid; the dominant strategy is to bid one’s true valuation (strategy-proof).

Externalities and Market Failures

Negative externality — cost imposed on third parties (e.g., pollution); market overproduces; corrected by a Pigouvian tax (Pigou, 1920).
Positive externality — benefit to third parties (e.g., vaccination, education); market underproduces; corrected by subsidies.
Coase theorem — if property rights are well-defined and transaction costs are negligible, private bargaining leads to the efficient outcome regardless of initial assignment (Coase, 1960).
Public goods — non-excludable and non-rival; susceptible to the free-rider problem; government typically provides them. Examples: national defense, lighthouses.
Common-pool resources — rival but non-excludable; susceptible to tragedy of the commons (overuse, Hardin 1968). Elinor Ostrom showed communities can self-govern commons (Nobel 2009).
Asymmetric information — Akerlof (lemons), Spence (signaling), Stiglitz (screening) shared the 2001 Nobel for foundational work.
Tragedy of the commons — Garrett Hardin (1968 Science article): unregulated shared resources are overexploited because each individual gains all the benefit of use but shares the cost with everyone; countered by Elinor Ostrom’s empirical work on successful community governance.
Externality — a cost or benefit falling on parties not involved in a transaction; negative (pollution) leads to overproduction; positive (vaccination) to underproduction relative to the social optimum.
Macroeconomics

National Accounts

GDP (Gross Domestic Product) — the market value of all final goods and services produced within a country in a period. Expenditure approach: GDP = C + I + G + (X - M).
Nominal vs real GDP — nominal uses current prices; real adjusts for inflation using a base-year price level. GDP deflator = (nominal/real) × 100.
GNP / GNI — Gross National Product / Income counts production by residents regardless of location; differs from GDP by net factor income from abroad.
GDP per capita — common (imperfect) measure of living standards; does not capture inequality or non-market activity.

Inflation and Unemployment

Inflation — sustained rise in the general price level. Measured by the CPI (consumer price index) or PCE (personal consumption expenditures, the Fed’s preferred measure).
CPI vs GDP deflator — CPI uses a fixed basket (Laspeyres); GDP deflator covers all domestically produced goods with a changing basket.
Types of inflation — demand-pull: excess aggregate demand; cost-push: supply-side cost increases; built-in (wage-price spiral).
Hyperinflation — extremely rapid inflation; classic cases: Germany 1921–23, Zimbabwe 2007–09.
Deflation — falling price levels; dangerous when it induces delayed spending and debt deflation spirals.
Unemployment types — frictional (job search between positions), structural (skill mismatch), cyclical (recession-driven). NAIRU: the non-accelerating inflation rate of unemployment.
Natural rate of unemployment — frictional + structural; the level consistent with stable inflation.
Okun’s law — empirical relationship: each 1-percentage-point rise in unemployment is associated with roughly a 2-percentage-point fall in GDP relative to potential.
Phillips curve — Phillips’s 1958 paper studied unemployment and the rate of change of money wages in the United Kingdom. Later versions relate unemployment or economic slack to price inflation. Expectations and supply shocks affect the relationship; it is not a fixed policy menu valid across all periods.³

Business Cycles and Policy

Business cycle phases — expansion, peak, contraction (recession), trough. A recession is conventionally two consecutive quarters of negative real GDP growth.
Aggregate demand / aggregate supply (AD-AS) model — AD slopes down; short-run AS (SRAS) slopes up; long-run AS (LRAS) is vertical at potential output.
Fiscal policy — government spending and taxation. Expansionary: increase G or cut T; contractionary: cut G or raise T. Subject to lags (recognition, legislative, implementation).
Fiscal multiplier — the change in output associated with a change in government spending or taxation; a government-purchases multiplier of 1 means one additional dollar of output per dollar of purchases. It need not exceed 1: its size depends on economic slack, monetary policy, financing, timing, and household or business responses.⁴
Automatic stabilizers — fiscal mechanisms that automatically dampen business cycles without new legislation: unemployment insurance, progressive income taxes.
Monetary policy — central bank actions to influence money supply and interest rates.
Quantity theory of money — MV = PQ (Fisher equation of exchange): money supply (M) times velocity (V) equals price level (P) times real output (Q); if V and Q are stable, money growth drives inflation.
IS-LM model — John Hicks’s formalization of Keynes: the IS curve (investment-saving equilibrium in goods market) and LM curve (liquidity preference-money supply equilibrium) jointly determine interest rates and output in the short run.
Keynesian cross — a simple model where output is determined by planned expenditure; equilibrium where the 45° line (output = income) intersects the aggregate expenditure function; illustrates the multiplier.
Multiplier effect — an initial change in spending is magnified through successive rounds of consumption; the multiplier = 1 / (1 − MPC), where MPC is the marginal propensity to consume.
Marginal propensity to consume (MPC) — the fraction of an additional dollar of income that is spent on consumption (the remainder is the marginal propensity to save, MPS); central to Keynesian multiplier analysis.
Solow growth model — Robert Solow (1956): long-run growth depends on capital accumulation, labor force growth, and exogenous technological progress; the Solow residual (total factor productivity) accounts for growth not explained by factor inputs; Nobel 1987.
Steady state (Solow) — the capital-per-worker level at which investment exactly offsets depreciation and labor force growth; without technological progress, the economy converges to zero per-capita growth.
Lucas critique — Robert Lucas (1976): econometric models that ignore how agents adjust their behavior when policy changes are structurally invalid for policy evaluation; foundational to rational expectations macroeconomics.
Rational expectations — John Muth (1961), extended by Lucas and Sargent: agents form expectations using all available information and the correct model of the economy; on average, they are not systematically wrong.
Real business cycle (RBC) theory — Kydland and Prescott (Nobel 2004): business cycles are efficient responses to real technology shocks; monetary policy is largely irrelevant; agents optimize intertemporally.
Efficient markets hypothesis (EMH) — Eugene Fama: asset prices fully reflect all available information; three forms: weak (past prices), semi-strong (public information), strong (all information including insider); Nobel 2013.
Natural rate of interest — the real interest rate consistent with potential output and stable inflation; a key concept in central bank policy (the “r-star”).
Permanent income hypothesis — Milton Friedman: consumption is determined by permanent (long-run average) income, not current income; transitory income shocks are largely saved.

Money and Central Banking

Money supply measures (United States) — under the Federal Reserve definition used from May 2020, M1 includes currency held outside banks, demand deposits, and other liquid deposits, including savings deposits. M2 adds small-denomination time deposits and retail money-market fund balances, with specified retirement-account exclusions. Historical series must be read with their definitions: savings deposits were formerly outside M1.⁵
Federal Reserve (Fed) — U.S. central bank; primary tools: federal funds rate target, open market operations (buying/selling Treasuries), reserve requirements, discount rate, and (since 2008) interest on reserves.
Fractional reserve banking — banks hold only a fraction of deposits as reserves; the rest is lent out, creating money. Money multiplier = 1 / reserve ratio (theoretical maximum).
Quantitative easing (QE) — large-scale asset purchases by central banks to expand reserves and lower long-term yields; used extensively after 2008 and in 2020.
Zero lower bound — the constraint that nominal interest rates cannot fall much below zero; requires unconventional tools like QE or forward guidance.
Lender of last resort — the central bank’s function of providing emergency liquidity to prevent bank runs; theorized by Bagehot.

International Economics

Absolute vs comparative advantage — absolute: can produce more with the same inputs. Comparative: can produce at lower opportunity cost. Countries gain from trade based on comparative advantage even if one has absolute advantage in all goods (Ricardo).
Heckscher-Ohlin model — countries export goods intensive in their abundant factors. Stolper-Samuelson theorem: trade benefits the abundant factor, harms the scarce factor.
Terms of trade — the ratio at which a country’s exports exchange for imports; a deterioration means more exports needed per unit of imports.
Balance of payments — records all international transactions: current account (trade in goods/services, income transfers) + capital account + financial account = 0.
Current account deficit — imports exceed exports + net income; must be financed by capital inflows. The U.S. has run a persistent deficit since the 1980s.
Exchange rates — fixed (pegged): government holds rate via intervention. Floating: determined by market. Purchasing power parity (PPP): exchange rates equalize price levels; used for cross-country GDP comparisons.
Stolper-Samuelson theorem — in the Heckscher-Ohlin framework, trade raises the real return to the abundant factor and lowers the real return to the scarce factor; explains why trade creates distributional winners and losers within countries.
Factor price equalization theorem — corollary of Heckscher-Ohlin: under idealized conditions, free trade equalizes factor prices (wages, capital returns) across countries.
Marshall-Lerner condition — a devaluation improves the current account only if the sum of import and export price elasticities exceeds 1.
J-curve — after devaluation, the trade balance initially worsens (existing contracts) before improving; traces a J shape.
WTO — World Trade Organization; oversees multilateral trade rules, dispute resolution; succeeded GATT (1947) in 1995.
IMF / World Bank — IMF: balance-of-payments support and macroeconomic stability. World Bank: development lending.

Empirical Methods and Causal Inference

Economic theory proposes mechanisms; empirical economics asks what the data identify about them. A correlation, a forecast, and a causal effect answer different questions.

Identification — the assumptions and research design that connect an observed comparison to a quantity of interest, such as the effect of a policy. More observations can improve precision without removing confounding or selection bias.
Randomized experiments — random assignment creates comparable treatment groups in expectation. The intention-to-treat effect concerns assignment; estimating the effect of treatment actually received requires addressing noncompliance. Random assignment does not itself guarantee generalization to other populations.
Natural experiments — use circumstances that generate plausibly exogenous variation. Credibility depends on how exposure was assigned and which alternative explanations the design excludes. Card, Angrist, and Imbens were recognized by the 2021 economics prize for empirical and methodological work in this tradition.
Difference-in-differences — compares changes over time between exposed and comparison groups. A central identifying assumption is that their untreated outcomes would have followed parallel trends; similar pre-intervention trends are useful evidence but cannot prove that counterfactual assumption.
Instrumental variables — uses a variable that changes exposure while satisfying independence and exclusion assumptions. Under additional conditions, including monotonicity in the standard binary-instrument setting, the estimate can identify an effect for people whose exposure changes with the instrument; it need not equal the population-average effect.
Prediction and policy — a model that forecasts well within one setting may not identify the effects of an intervention. Report effect sizes and uncertainty, justify the comparison group, and distinguish local evidence from claims about different institutions or populations.⁶

Schools of Thought

Classical economics — Adam Smith, Ricardo, Mill; markets self-correct via price flexibility; laissez-faire; supply creates its own demand (Say’s law).
Say’s law — “supply creates its own demand”: production generates sufficient income to purchase all output; implies no sustained general gluts; contested by Keynes, who argued demand deficiencies are possible.
Gresham’s law — “bad money drives out good”: when two forms of currency are in circulation and one is undervalued, people hoard the better currency and spend the worse; attributed to Tudor financier Thomas Gresham.
Marxian economics — Marx; labor theory of value; surplus value extracted by capitalists; capitalism contains internal contradictions leading to crisis and eventual collapse. Key works: Das Kapital (vol. 1, 1867).
Labor theory of value — the view (classical and Marxian) that the value of a commodity is determined by the socially necessary labor time required to produce it; Marx used it to analyze exploitation and surplus value.
Keynesian economics — Keynes; aggregate demand drives output; markets can get stuck at below-full-employment equilibria; government spending can stimulate recovery. Key work: The General Theory (1936).
Neoclassical synthesis — post-WWII merging of Keynesian macro with neoclassical micro (Samuelson, Hicks, Modigliani).
Monetarism — Milton Friedman; money supply growth is the primary determinant of nominal GDP and inflation; stable money-growth rules preferred over discretionary policy. Key work: A Monetary History of the United States (1963, with Anna Schwartz).
Rational expectations / New Classical — Lucas, Sargent; agents use all available information to form expectations; anticipated policy is ineffective (policy ineffectiveness proposition).
New Keynesian — Mankiw, Romer; incorporates rational expectations but retains price stickiness and market failures; provides microfoundations for Keynesian results.
Austrian school — Mises, Hayek; emphasis on subjective value, entrepreneurship, and the knowledge problem (price signals aggregate dispersed information that no central planner can replicate). Hayek’s The Road to Serfdom (1944).
Behavioral economics — Thaler, Kahneman, Tversky; systematic cognitive biases (loss aversion, anchoring, hyperbolic discounting) cause deviations from rational choice. Nudge theory (Thaler/Sunstein).
Institutional economics — Veblen, Commons; institutions and power structures shape economic behavior. New institutional economics: Coase, North, Williamson; transaction costs and property rights.

Key Economists and Works

Adam Smith (1723–1790) — The Wealth of Nations (1776): division of labor, price mechanism, the invisible hand; The Theory of Moral Sentiments (1759).
David Ricardo (1772–1823) — comparative advantage; theory of rent; labor theory of value; Principles of Political Economy and Taxation (1817).
Thomas Malthus (1766–1834) — population grows geometrically while food supply grows arithmetically, predicting subsistence misery; Essay on the Principle of Population (1798).
John Stuart Mill (1806–1873) — refined classical economics; utilitarianism; Principles of Political Economy (1848).
Karl Marx (1818–1883) — surplus value, modes of production, historical materialism; Das Kapital vol. 1 (1867); The Communist Manifesto (1848, with Engels).
Alfred Marshall (1842–1924) — supply and demand curves; consumer/producer surplus; partial equilibrium analysis; Principles of Economics (1890).
Vilfredo Pareto (1848–1923) — Pareto efficiency (no one can be made better off without making someone worse off); Pareto distribution; 80/20 rule.
John Maynard Keynes (1883–1946) — aggregate demand, multiplier, liquidity trap, fiscal stimulus; The General Theory of Employment, Interest and Money (1936).
Joseph Schumpeter (1883–1950) — creative destruction: innovation destroys old industries while creating new ones; entrepreneurship as engine of capitalism; Capitalism, Socialism and Democracy (1942).
Friedrich Hayek (1899–1992) — knowledge problem, business cycle theory, critique of central planning; Nobel 1974; The Road to Serfdom (1944).
Paul Samuelson (1915–2009) — neoclassical synthesis; mathematical formalization of economics; first American Nobel laureate (1970). Foundations of Economic Analysis (1947).
Milton Friedman (1912–2006) — monetarism, natural rate of unemployment, permanent income hypothesis; Nobel 1976; A Monetary History of the United States (1963).
Kenneth Arrow (1921–2017) — Arrow’s impossibility theorem; general equilibrium theory; Nobel 1972.
Robert Solow (1924–2023) — Solow growth model; technological progress as the residual driver of long-run growth; Nobel 1987.
Paul Krugman (b. 1953) — new trade theory (economies of scale + imperfect competition explain trade patterns); Nobel 2008; also known for The Return of Depression Economics and prolific public commentary.
Daniel Kahneman (b. 1934) — behavioral economics; prospect theory (with Amos Tversky): people value gains and losses asymmetrically (loss aversion) and weight probabilities nonlinearly; Nobel 2002; Thinking, Fast and Slow (2011).
Amos Tversky (1937–1996) — co-developed prospect theory and cognitive heuristics (availability, representativeness, anchoring) with Kahneman; died before the 2002 Nobel could be shared.
Richard Thaler (b. 1945) — behavioral economics; nudge theory (with Cass Sunstein): choice architecture can steer decisions without restricting options; mental accounting, endowment effect; Nobel 2017.
Joseph Stiglitz (b. 1943) — asymmetric information (screening); critiques of IMF austerity; Globalization and Its Discontents (2002); Nobel 2001.
Thomas Piketty (b. 1971) — Capital in the Twenty-First Century (2013): r > g thesis (return on capital exceeds economic growth) drives rising inequality; proposes global wealth tax; sparked major debate on long-run inequality trends.
Elinor Ostrom (1933–2012) — governance of the commons; Nobel 2009 (first woman to win).
John Nash (1928–2015) — formalized Nash equilibrium in non-cooperative games (PhD thesis, 1950); Nobel 1994; subject of A Beautiful Mind; died in a taxi accident with wife Alicia.
Léon Walras (1834–1910) — general equilibrium theory: prices in all markets adjust simultaneously until all markets clear; Éléments d’économie politique pure (1874); founder of the Lausanne school.
Ronald Coase (1910–2013) — Coase theorem on property rights and externalities; also “The Nature of the Firm” (1937): firms exist because markets have transaction costs; Nobel 1991.
George Akerlof (b. 1940) — “The Market for Lemons” (1970); Nobel 2001; married to Janet Yellen.
Finn Kydland (b. 1943) and Edward Prescott (1940–2022) — real business cycle theory; also time inconsistency: optimal policy announced today may not be optimal to implement later, arguing for rules over discretion in monetary policy; Nobel 2004.
Robert Lucas (1937–2023) — Lucas critique; rational expectations; Lucas supply curve; Nobel 1995.
Eugene Fama (b. 1939) — efficient markets hypothesis; empirical work on asset pricing and the three-factor model (with French); Nobel 2013.
Robert Shiller (b. 1946) — irrational exuberance and asset price bubbles; CAPE (Cyclically Adjusted P/E) ratio; Irrational Exuberance (2000) and Animal Spirits (with Akerlof); Nobel 2013.
Gary Becker (1930–2014) — human capital theory (investment in education and health as capital); economics of crime; discrimination; Human Capital (1964); Nobel 1992.
Herbert Simon (1916–2001) — bounded rationality: real decision-makers face cognitive and informational limits; satisficing (choosing a “good enough” option rather than optimizing); Nobel 1978.
David Card (b. 1956) — natural experiments in labor economics; minimum wage studies (with Alan Krueger) challenging the prediction that minimum wages always reduce employment; Nobel 2021.
Gunnar Myrdal (1898–1987) — cumulative causation: poverty begets poverty through self-reinforcing cycles; An American Dilemma (1944) on race in the U.S.; Nobel 1974.
Thorstein Veblen (1857–1929) — institutional economics; conspicuous consumption and pecuniary emulation; The Theory of the Leisure Class (1899); coined “Veblen good.”
John von Neumann (1903–1957) — co-founder of game theory with Oskar Morgenstern; minimax theorem; Theory of Games and Economic Behavior (1944).
Oskar Morgenstern (1902–1977) — co-authored Theory of Games and Economic Behavior (1944) with von Neumann; formalized utility theory for game theory.
Douglass North (1920–2015) — new institutional economics; institutions (rules, norms, enforcement mechanisms) shape economic performance and path dependence; Nobel 1993.
Oliver Williamson (1932–2020) — transaction cost economics; explains why firms (hierarchies) sometimes replace markets; Nobel 2009.
Fischer Black (1938–1995) — Black-Scholes options pricing formula; Black-Litterman portfolio model; died before 1997 Nobel (prizes not awarded posthumously).
Jan Tinbergen (1903–1994) — Tinbergen rule: to achieve n independent policy targets, a government needs at least n independent policy instruments; econometric modeling; first Nobel laureate in economics (1969, shared with Frisch).
Ragnar Frisch (1895–1973) — coined “econometrics” and “macroeconomics”; co-founder of the Econometric Society; first Nobel laureate in economics (1969).
Arthur Okun (1928–1980) — Okun’s law (see Macroeconomics section); also developed the misery index (inflation rate + unemployment rate) as a simple welfare measure.
A.W. (Alban William) Phillips (1914–1975) — empirical inverse relationship between wage inflation and unemployment, observed in UK data 1861–1957; Economica (1958); the “Phillips curve” bears his name.
Edmund Phelps (b. 1933) — independently derived the long-run vertical Phillips curve and the natural rate of unemployment alongside Friedman (1968); Nobel 2006.
Paul Romer (b. 1955) — endogenous growth theory: technological change is the result of intentional investment in R&D, not exogenous; Nobel 2018 (shared with Nordhaus).
William Nordhaus (b. 1941) — integrated assessment models linking climate and economics; Nobel 2018 (shared with Romer).
Robert M. Solow (1924–2023) — born 23 August 1924; awarded the 1987 economics prize for contributions to the theory of economic growth. His 1956 growth paper distinguished capital accumulation from sustained growth driven by technical change.⁷
Heckscher–Ohlin trade theory — Eli Heckscher developed the factor-endowment approach, which Bertil Ohlin extended in Interregional and International Trade (1933). In the standard model, countries export goods intensive in their relatively abundant factors. Ohlin shared the 1977 economics prize with James Meade.⁸
Piketty’s r > g — r denotes the rate of return on capital and g economic growth. A larger gap can amplify wealth concentration in models with unequal saving, inheritance, and returns; it is not a sufficient condition that mechanically makes inequality rise in every economy. Piketty treats institutions, shocks, and policy as essential parts of the explanation.⁹
Irving Fisher (1867–1947) — quantity theory of money; Fisher equation (nominal interest rate = real rate + expected inflation); debt-deflation theory of depressions.
John Kenneth Galbraith (1908–2006) — institutionalist critic of mainstream economics; The Affluent Society (1958) argued that private wealth coexists with public squalor; concept of countervailing power.
Simon Kuznets (1901–1985) — developed national income accounting and GDP measurement; Kuznets curve hypothesis (inequality first rises then falls with development); Nobel 1971.
Wassily Leontief (1906–1999) — input-output analysis: models interdependencies between industrial sectors using input-output tables; Nobel 1973.
James Tobin (1918–2002) — Tobin’s q (ratio of market value to replacement cost of capital as an investment guide); Tobin tax proposal on financial transactions; portfolio selection theory; Nobel 1981.
Franco Modigliani (1918–2003) — life-cycle hypothesis (individuals smooth consumption over their lifetimes); Modigliani-Miller theorem (capital structure irrelevance under idealized conditions); Nobel 1985.
James Buchanan (1919–2013) — public choice theory: applies economic (self-interest) reasoning to political actors and institutions; analysis of government failure; Nobel 1986.
Harry Markowitz (1927–2023) — modern portfolio theory: diversification formally reduces risk; efficient frontier of optimal portfolios; Nobel 1990 (shared with Miller and Sharpe).
William Sharpe (b. 1934) — Capital Asset Pricing Model (CAPM): asset returns depend on systematic (market) risk (beta) alone in equilibrium; Nobel 1990.
Robert Merton (b. 1944) — continuous-time finance; extended Black-Scholes options pricing model; Nobel 1997.
Myron Scholes (b. 1941) — Black-Scholes options pricing formula (with Fischer Black): first closed-form model for pricing European options; Nobel 1997.
Amartya Sen (b. 1933) — welfare economics and social choice theory; capabilities approach (well-being measured by what people can do and be, not just income); work on famine as a failure of entitlements; Nobel 1998.
Robert Mundell (1932–2021) — optimal currency area theory (conditions under which countries benefit from a common currency); Mundell-Fleming model of open-economy macroeconomics; Nobel 1999.
Thomas Schelling (1921–2016) — focal points (Schelling points) in coordination games; segregation models; The Strategy of Conflict (1960); Nobel 2005.
Jean Tirole (b. 1953) — industrial organization and regulation theory; analysis of market power and optimal regulation of firms with private information; Nobel 2014.
Angus Deaton (b. 1945) — measurement of consumption, poverty, and welfare; Almost Ideal Demand System; work on global poverty and inequality; The Great Escape (2013); Nobel 2015.

Landmark Concepts

Invisible hand — Smith’s metaphor: individuals pursuing self-interest are guided, as if by an invisible hand, to promote the public good through market prices.
Creative destruction — Schumpeter: capitalism advances through the constant destruction of old economic structures and creation of new ones via innovation.
Deadweight loss — welfare lost due to market inefficiency (monopoly pricing, taxes, externalities); the area of the triangle between supply and demand curves between competitive and distorted quantities.
Moral hazard / adverse selection — post-contract and pre-contract information problems, respectively (see Market Failures above).
Ricardian equivalence — Barro: if consumers anticipate future taxes to repay deficit spending, they save the stimulus rather than spend it, neutralizing fiscal policy.
Dutch disease — a natural-resource boom appreciates the real exchange rate, crowding out manufacturing exports.
Gini coefficient — measures income inequality; 0 = perfect equality, 1 = maximum inequality. Lorenz curve plots cumulative income share against cumulative population share.
Laffer curve — at tax rates of 0% and 100%, revenue is zero; somewhere in between is the revenue-maximizing rate. Theoretical basis for supply-side tax-cut arguments.
Rent-seeking — using resources to obtain transfers (e.g., lobbying for monopoly privileges) rather than creating wealth.
Moral economy / just price — pre-modern concept that prices should reflect fairness, not just supply and demand; studied by Thompson (1971) in the context of bread riots.
Kuznets curve — Simon Kuznets’s hypothesis that income inequality first rises and then falls as a country industrializes and develops (an inverted U-shape); empirically disputed; also adapted as the environmental Kuznets curve for pollution.
Modigliani-Miller theorem — under idealized conditions (no taxes, bankruptcy costs, or asymmetric information), a firm’s value is independent of its capital structure (debt-to-equity ratio); Franco Modigliani and Merton Miller, 1958.
Capital Asset Pricing Model (CAPM) — expected return of an asset = risk-free rate + beta × (market return − risk-free rate); beta measures systematic (non-diversifiable) risk; associated with William Sharpe and John Lintner.
Efficient frontier — Harry Markowitz’s concept: the set of portfolios offering the highest expected return for a given level of risk; portfolios below the frontier are suboptimal.
Time value of money — a dollar today is worth more than a dollar in the future due to earning potential; basis for discounted cash flow analysis and net present value (NPV) calculations.
Endowment effect — Richard Thaler: people demand more to give up an object than they would pay to acquire it; a form of loss aversion that violates standard preference theory.
Loss aversion — Kahneman-Tversky finding: the pain of a loss is roughly twice the pleasure of an equivalent gain; cornerstone of prospect theory.
Hyperbolic discounting — people discount the near future more steeply than the far future, leading to time-inconsistent preferences and present bias; explains procrastination and undersaving.
Nudge — Thaler and Sunstein: a choice architecture intervention that steers behavior toward better outcomes without coercion or financial incentives (e.g., default enrollment in pension plans).
Human capital — Gary Becker: investment in education, health, and training raises worker productivity; explains wage differentials and the return to schooling.
Comparative advantage (Ricardian) — a country has a comparative advantage in goods it can produce at the lowest opportunity cost, even if it is less productive in absolute terms than trading partners; the classic example uses England (cloth) and Portugal (wine); published in Principles of Political Economy and Taxation (1817).
General equilibrium — Léon Walras: all markets in an economy reach equilibrium simultaneously; formalized rigorously by Arrow and Gérard Debreu in the 1950s (Arrow-Debreu model).
Fiscal cliff — the simultaneous expiration of tax cuts and onset of spending cuts that would sharply tighten fiscal policy; a policy concept popularized during the U.S. 2012–2013 debate.
Liquidity trap — Keynes: when interest rates are near zero, monetary policy becomes ineffective because people hoard cash rather than invest; associated with Japan’s “lost decade” and post-2008 advanced economies.
Animal spirits — Keynes’s term for the spontaneous urge to action that drives investment decisions, beyond purely rational calculation; revived by Akerlof and Shiller in Animal Spirits (2009).
Crowding out — government borrowing raises interest rates, reducing private investment; the offset reduces the net effect of fiscal stimulus.
Supply-side economics — emphasizes cutting taxes (especially on high earners and capital) to stimulate investment and growth; associated with the Laffer curve and Reaganomics in the 1980s.

Nobel Memorial Prize Highlights

Year	Laureate(s)	Contribution
1969	Frisch, Tinbergen	Founding of econometrics
1971	Kuznets	National income accounting; Kuznets curve
1973	Leontief	Input-output analysis
1974	Hayek, Myrdal	Money, business cycles (Hayek); institutional analysis (Myrdal)
1976	Friedman	Monetarism, consumption analysis
1978	Simon	Bounded rationality, decision-making in organizations
1981	Tobin	Portfolio theory; Tobin’s q
1985	Modigliani	Life-cycle hypothesis; Modigliani-Miller theorem
1986	Buchanan	Public choice theory
1990	Markowitz, Miller, Sharpe	Portfolio theory (Markowitz); CAPM (Sharpe)
1994	Nash, Harsanyi, Selten	Non-cooperative game theory
1997	Merton, Scholes	Options pricing (Black-Scholes model)
1998	Sen	Welfare economics; capabilities approach
1999	Mundell	Optimal currency areas; Mundell-Fleming model
2001	Akerlof, Spence, Stiglitz	Asymmetric information markets
2002	Kahneman, Smith	Behavioral economics; experimental economics
2005	Aumann, Schelling	Game theory and conflict analysis
2008	Krugman	New trade theory and economic geography
2009	Ostrom, Williamson	Commons governance; transaction-cost economics
2013	Fama, Hansen, Shiller	Empirical asset pricing
2014	Tirole	Industrial organization and regulation
2015	Deaton	Consumption, poverty, and welfare measurement
2017	Thaler	Behavioral economics, nudge theory
2021	Card, Angrist, Imbens	Causal inference in empirical economics (natural experiments)
2022	Bernanke, Diamond, Dybvig	Banks and financial crises; Diamond-Dybvig model of bank runs
2023	Claudia Goldin	Women’s labor market outcomes and gender pay gap
2024	Acemoglu, Johnson, Robinson	Institutions and prosperity; Why Nations Fail (Acemoglu/Robinson)