Theory c. 1776
The Invisible Hand
Adam Smith's metaphor describing how individuals pursuing their own self-interest are led, as if by an invisible hand, to promote the economic well-being of society as a whole.
Economic Theories
The frameworks, models, and ideas that define how we understand markets, money, labor, and growth.
Theory c. 1776
The Labor Theory of Value
The idea that the economic value of a good is determined by the total amount of labor required to produce it, a cornerstone of classical economics that shaped debates from Smith through Marx.
Theory c. 1817
Comparative Advantage
The principle that nations benefit from trade by specializing in goods they produce at the lowest opportunity cost, even if one nation is more efficient at producing everything.
Theory c. 1871
Marginal Utility
The principle that the value of a good is determined by the satisfaction gained from one additional unit, resolving the classical water-diamond paradox and revolutionizing price theory.
Theory c. 1874
General Equilibrium Theory
The mathematical framework showing how prices in all markets can simultaneously adjust to clear supply and demand, forming the theoretical backbone of modern microeconomics.
Theory c. 1911
The Quantity Theory of Money
The proposition that the general price level is determined by the money supply, crystallized in Fisher's equation of exchange and revived by Friedman's monetarism.
Theory c. 1933
Debt-Deflation Theory
Irving Fisher's theory of how over-indebtedness and falling prices create a self-reinforcing spiral of economic collapse, later extended by Hyman Minsky into a broader theory of financial instability.
Theory c. 1936
Effective Demand
Keynes's argument that the overall level of economic activity is determined by aggregate demand, not supply, and that economies can settle into prolonged underemployment equilibrium.
Theory c. 1936
The Keynesian Multiplier
The principle that an initial injection of government spending generates a larger total increase in national income as the spending circulates through the economy via successive rounds of consumption.
Theory c. 1936
Liquidity Preference Theory
Keynes's explanation of interest rate determination through the supply and demand for money, emphasizing why people choose to hold wealth in liquid form rather than earning a return.
Theory c. 1937
Transaction Cost Economics
The theory that explains why firms exist and how the costs of using markets shape the boundaries between organizations and market exchange.
Theory c. 1942
Creative Destruction
Joseph Schumpeter's theory that capitalism evolves through a perpetual cycle in which innovative entrepreneurs destroy established industries, driving economic progress through disruption rather than equilibrium.
Theory c. 1945
Spontaneous Order
Hayek's insight that complex social orders like markets, language, and law emerge from decentralized human action without central planning or design.
Theory c. 1958
The Phillips Curve
The empirical relationship between unemployment and inflation that became the central battleground of macroeconomic policy debate for half a century.
Theory c. 1959
Endogenous Money Theory
The post-Keynesian argument that money is created endogenously by commercial banks making loans, rather than exogenously by central banks controlling the money supply.
Theory c. 1961
Rational Expectations
The hypothesis that economic agents form expectations about the future using all available information efficiently, implying that systematic policy cannot fool the public.
Theory c. 1963
Moral Hazard
The tendency for people to take greater risks when they are insulated from the consequences, a concept that leapt from insurance theory to the center of financial crisis debates.
Theory c. 1968
The Natural Rate of Unemployment
Milton Friedman's concept of an equilibrium unemployment rate determined by structural and institutional factors, not monetary policy, which transformed the debate over government's ability to manage the labor market.
Theory c. 1968
Tragedy of the Commons
The theory that shared resources are inevitably depleted when individuals, acting in rational self-interest, overconsume a common-pool resource -- and Elinor Ostrom's empirical demonstration that communities can and do solve this problem without privatization or state control.
Theory c. 1979
Prospect Theory
Kahneman and Tversky's groundbreaking model of how people actually make decisions under risk, revealing systematic departures from the rational actor assumed by classical economics.