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The Wisdom of Crowds

“Under the right circumstances, groups are remarkably intelligent, and are often smarter than the smartest people in them.”

“Men, it has been well said, think in herds, wrote Scottish journalist Charles Mackay in Extraordinary Popular Delusions and the Madness of Crowds, his satirical 1841 history of mass manias and popular folly. “It will be seen that they go mad in herds, while they only recover their senses slowly, and one by one.”

In this episode from PBS’s NOVA ScienceNOW video podcast series, Neil deGrasse Tyson tells the story of British polymath Francis Galton, who in 1906 set out to confirm Mackay’s contention but found, instead, the opposite: That crowds can have astonishing collective intelligence that far supersedes the cognitive capacity of individuals.

In The Wisdom of Crowds (public library), whose title plays on Mackay’s book, James Surowiecki examines Galton’s insight more closely to demonstrate how, under the right circumstances, groups — from game-show audiences to multibillion-dollar corporations — “are remarkably intelligent, and are often smarter than the smartest people in them.” He recounts Galton’s experiment and its connotation for democracy. (Ironically, Surowiecki wrote this years before the Arab Spring, Occupy Wall Street, and Anonymous.)

One day in the fall of 1906, the British scientist Francis Galton headed for the country fair.


As he walked through the exhibition that day, Galton came across a weight-judging competition. A fat ox had been selected and members of a gathering crowd were lining up to place wagers on the (slaughtered and dressed) weight of the ox.


Eight hundred people tried their luck. They were a diverse lot. Many of them were butchers and farmers, but there were also quite a few who had no insider knowledge of cattle. ‘Many non-experts competed,’ Galton wrote later in the scientific journal Nature, ‘like those clerks and others who have no expert knowledge of horse, but who bet on races, guided by newspapers, friends, and their own fancies.’ The analogy to a democracy, in which people of radically different abilities and interests each get one vote, had suggested itself to Galton immediately. ‘The average competitor was probably as well fitted for making a just estimate of the dressed weight of the ox, as an average voter is of judging the merits of most political issues on which he votes,’ he wrote.

Galton was interested in figuring out what the ‘average voter’ was capable of because he wanted to prove that the average voter was capable of very little. So he turned the competition into an impromptu experiment. When the contest was over and the prizes had been awarded, Galton borrowed the tickets from the organizers and ran a series of statistical tests on them, including the mean of the group’s guesses.


Galton undoubtedly thought that the average guess of the group would be way off the mark. After all, mix a few very smart people with some mediocre people and a lot of dumb people, and it seems like you’d end up with a dumb answer. But Galton was wrong — the crowd guessed 1,197 pounds; after it had been slaughtered and dressed the ox weighed 1,198 pounds. In other words, the crowd’s judgment was essentially perfect…. Galton wrote later: ‘The result seems more creditable to the trustworthiness of a democratic judgment than might have been expected.’ That was, to say the least, an understatement.

Published August 6, 2012




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