Microeconomics

Consumer Theory

This guide helps you get your bearings in Consumer Theory before you start exploring the interactive timeline, framework graph, and concept maps.

Before You Dive In

Consumer theory is the mathematical framework for how individuals make choices — it's the microeconomic foundation that everything else builds on.
The core model (utility maximization subject to a budget constraint) is elegant but relies on strong assumptions that behavioral economics challenges.
Start with indifference curves and budget constraints — they visualize the trade-offs consumers face.
The progression from cardinal utility (Jevons) → ordinal utility (Pareto, Hicks) → revealed preference (Samuelson) shows how the theory became more rigorous by assuming less.

Utility functionMathematical representation of a consumer's preferences over bundles of goods.

Indifference curveAll combinations of goods that give a consumer equal satisfaction.

Budget constraintThe set of affordable bundles given prices and income.

Marginal rate of substitutionThe rate at which a consumer trades one good for another while staying equally satisfied.

Revealed preferenceInferring preferences from observed choices rather than assumed utility functions.

Thinking utility is measurable in real units — modern theory only requires ordinal rankings (A is preferred to B), not cardinal amounts.

Assuming consumer theory claims people are perfectly rational — it's a model, and economists actively study when and how it breaks down.

Confusing consumer theory with demand theory — consumer theory generates demand curves, but demand analysis also works with empirical data directly.

Open the interactive view and scan the framework timeline. Which frameworks came first? Which ones overlap? Where are the big transitions?

Click into individual frameworks to read what each one claims, where it came from, and how it relates to its neighbors.

See how the key ideas within a framework connect. This is useful for figuring out what to learn first and what depends on what.

Take the quiz for any framework you've read about. It's a quick way to find out whether you actually understood the core ideas or just skimmed them.