Vernon L. Smith

Vernon L. Smith’s significance in The Wisdom of Crowds lies in a simple but consequential test: could an actual market of imperfectly informed people reach an efficient result? In January 1956, he made his classroom a laboratory. The experiment showed that students trading with only fragments of private information could converge on a near-ideal outcome, turning an abstract economic proposition into an observable result.

From Economic Theory to a Classroom Laboratory

When Smith began his experiment, classroom tests were an unusual way to investigate economics. The field was generally concerned with mathematical proofs or the analysis of real-world markets; the prevailing assumption was that laboratory exercises could reveal little about economic life. The best-known precedent was a simulated market set up each year by Harvard professor Edward Chamberlin. Smith had been one of Chamberlin’s students, and he took the experimental approach further.

Smith’s January 1956 market involved 22 students, divided evenly into buyers and sellers. Each seller received a card stating the lowest acceptable price, while each buyer received one stating the highest price they were willing to pay. Those private values allowed Smith to construct the class’s supply and demand schedules and calculate where they should meet. Students then traded in a double auction: buyers called out bids, sellers called out asking prices, and anyone could accept an offer. Successful trades were recorded on a blackboard at the front of the room.

Convergence Without Complete Knowledge

Smith wanted to test a prediction of economic theory: that exchange between buyers and sellers would quickly converge on the market-clearing price, where supply and demand meet. It did. Offers moved toward a single price even though buyers preferred lower prices, sellers preferred higher ones, and the students knew nothing about one another beyond the prices on their cards. The market also maximized the group’s total gain from trading; even someone with perfect knowledge could not have directed the students to do better.

That finding mattered because the ideal market described by the general-equilibrium theorem of Kenneth J. Arrow and Gerard Debreu depended on conditions no actual market could fully meet. In the theorem’s world, buyers and sellers have complete information, perfect rationality, and contracts covering every conceivable state. Real people have partial information, may be uncertain about how best to pursue their interests, and cannot rely on complete contracts. Smith’s experiment addressed the gap between that idealized model and ordinary economic behavior: it showed that a market populated by imperfect people could nevertheless produce a near-ideal result.

Why the Result Was Not Obvious

The result initially seemed so familiar to some economists that the Journal of Political Economy rejected Smith’s paper on its first submission. The journal eventually published it despite four negative referee judgments. The experiment’s importance was not simply that it supported a longstanding claim about markets. It demonstrated that market efficiency could emerge among real traders, rather than only under the assumptions of a mathematical proof.

The students themselves did not experience the process as a clear, deliberate search for the best outcome. Some found trading chaotic and confusing, and they described their choices as the best decisions they could make at the time. Yet, using only their private information, they found their way to the market’s efficient result. The contrast between their uncertainty and the group’s performance is central to the book’s account of collective intelligence: an orderly outcome need not depend on any participant possessing a complete picture.

Influence and Limits

In the four decades after Smith’s first experiment and publication of its results, researchers replicated the tests hundreds or perhaps thousands of times, using increasingly complex variations. The central conclusion—that imperfect people can achieve near-perfect results under suitable conditions—remained intact. Smith’s work thus helped make classroom experiments a tool for studying how markets function, rather than treating actual human behavior as an obstacle that theory could simply set aside.

The experiments do not establish that markets always produce ideal outcomes. A classroom lacks many of the imperfections found in real markets, and the results differ by market type: students buying and selling consumer goods such as televisions tend to reach the right outcome quickly, while markets in assets such as stocks are more volatile and erratic. Smith’s experiment therefore supports a conditional claim, not an unrestricted defense of every market. Its enduring contribution is more precise: even when individuals possess only limited, private information, the structure of exchange can sometimes aggregate their judgments into an outcome that no individual could have supplied alone.