A living compendium of economic thought — annotated, illustrated, and occasionally interrupted by fish.
The fundamental model of price determination in a market. The price of a good is set at the point where the quantity demanded by consumers equals the quantity supplied by producers. When these curves shift, everything we thought we knew about equilibrium gets beautifully, terrifyingly disrupted.
See also: why your coffee costs $7 now"The difficulty lies not so much in developing new ideas as in escaping from old ones." — J.M. Keynes
The total monetary value of all finished goods and services produced within a country's borders in a specific time period. GDP serves as a comprehensive scorecard of a nation's economic health, though its limitations as a measure of actual well-being have been debated since its inception.
GDP can be calculated three ways: the production approach, the income approach, or the expenditure approach. The expenditure formula is the most familiar:
GDP = C + I + G + (X − M)
Where C = consumption, I = investment, G = government spending, X = exports, M = imports. Simple, right? Devastatingly so.Fig. 1 — Supply & Demand Equilibrium
Adam Smith's metaphor for the unseen market force that guides individuals pursuing self-interest to promote society's well-being. A concept so elegant it has survived 250 years of economists trying to complicate it.
Smith used this phrase exactly three times. We've used it three million.The revolutionary framework developed by John Maynard Keynes during the Great Depression, arguing that aggregate demand — the total spending in an economy — is the primary driving force. When private sector demand falls short, government should step in with fiscal policy to fill the gap.
Keynes demolished the classical assumption that markets naturally return to full employment. His General Theory (1936) argued that economies can settle into equilibrium at any level of employment — including catastrophically low ones.
The paradox of thrift: when everyone saves, everyone loses. Keynes understood this before behavioral economics was born."Inflation is always and everywhere a monetary phenomenon." — Milton Friedman
The school of thought that emphasizes the role of governments in controlling the amount of money in circulation. Milton Friedman's counter-revolution against Keynesianism argued that steady, predictable growth in the money supply is the key to economic stability.
Control the money, control the world. Or at least the interest rates.Fig. 2 — The Phillips Curve Trade-off
The proposition that the economic value of a good is determined by the total amount of socially necessary labor required to produce it. Developed by Adam Smith and David Ricardo, then radically extended by Karl Marx into a critique of capitalist exploitation.
Marx argued that the difference between the value workers create and the wages they receive constitutes "surplus value" — the source of profit systematically extracted from labor by capital.
The factory doesn't just produce commodities. It produces the social relations that make commodities possible."The curious task of economics is to demonstrate to men how little they really know about what they imagine they can design." — F.A. Hayek
The additional satisfaction that a consumer derives from consuming one more unit of a good or service. The law of diminishing marginal utility explains why the first slice of pizza is ecstasy and the seventh is regret.
Diminishing returns: applicable to pizza, money, and economic theories themselvesFounded by Carl Menger in the 1870s, the Austrian School emphasizes individual choice, spontaneous order, and the limits of central planning. Its practitioners — including Ludwig von Mises and Friedrich Hayek — developed the theory of the business cycle driven by credit expansion.
The Austrian approach relies on deductive reasoning from axioms about human action (praxeology) rather than empirical statistical modeling. This makes it either profoundly philosophical or hopelessly unscientific, depending on whom you ask.
Hayek won the Nobel Prize in 1974. His co-laureate was Gunnar Myrdal, a socialist. The committee had a sense of humor.A sustained increase in the general price level of goods and services over time. When inflation rises, each unit of currency buys fewer goods — purchasing power erodes, debts become easier to repay, and savers watch their patience punished.
2% is the target. 10% is the nightmare. 0% is the trap."The philosophers have only interpreted the world, in various ways. The point, however, is to change it." — Karl Marx
Fig. 3 — Prisoner's Dilemma Payoff Matrix
David Ricardo's elegant proof that trade benefits all parties, even when one party is absolutely better at producing everything. What matters is not absolute efficiency but relative opportunity cost — each nation should specialize where their opportunity cost is lowest.
This principle demolished mercantilist protectionism and remains the intellectual foundation of free trade. It is also routinely ignored by politicians who find tariffs more emotionally satisfying than economic logic.
Ricardo figured this out in 1817. We're still arguing about it in every election cycle.The tendency of a party insulated from risk to behave differently than if fully exposed. When banks know they'll be bailed out, they take bigger gambles. When insurance covers everything, people get reckless. Protection creates its own dangers.
Too big to fail = too dangerous to exist?The value of the next-best alternative foregone when making a choice. Every decision is simultaneously a rejection of every other possibility. The true cost of anything is what you gave up to get it.
Reading this entry cost you approximately 30 seconds of your life. Worth it?Fig. 4 — Production Possibilities Frontier
The study of strategic interaction between rational decision-makers. Developed by John von Neumann and Oskar Morgenstern, later revolutionized by John Nash, game theory provides the mathematical framework for understanding how decisions depend on others' choices.
The Prisoner's Dilemma reveals the core tension: individual rationality can lead to collectively irrational outcomes. Nash equilibrium shows the stable state where no player can improve by unilaterally changing strategy — even when everyone would prefer a different outcome.
Nash saw mathematics in everything. Beautiful mind, terrible games."The ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood." — Keynes
Costs or benefits that affect parties not directly involved in a transaction. Pollution is a negative externality — the factory profits, the river suffers. Education is a positive externality — the student learns, society benefits.
The price tag never tells the whole story.A measure of how much one economic variable responds to a change in another. Price elasticity of demand reveals consumer sensitivity: necessities are inelastic, luxuries are elastic. The slope of human desire, quantified.
Insulin: perfectly inelastic. Designer handbags: embarrassingly elastic.Joseph Schumpeter's concept that capitalism's engine is the perpetual cycle of innovation destroying and replacing established industries. The horse-drawn carriage gives way to the automobile; the telegraph yields to the telephone; the bookstore falls to the algorithm.
Schumpeter saw this process as essential — the "essential fact about capitalism." Progress requires destruction. The entrepreneur is both creator and destroyer, birthing new worlds from the ruins of old ones.
Every tech startup is a Schumpeterian gale. Every bankruptcy is its aftermath."In the long run we are all dead." — J.M. Keynes