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Saturday, October 13, 2007

How the Majority Can Get It Wrong

Though I've written about mistakes we've made in the war in Iraq, I've been confident that I've correctly evaluated that we have been winning. The war has gone on long enough for me to be able to look back at points when we've had problems to see that I did not ignore those problems at the time. I just didn't panic over the nornal ebb and flow of warfare and ignore the fundamental trends.

Even as some war supporters flaked off, I have not been tempted to throw oup my hands and joint the retreat parade. I trust my judment to evaluate this war.

This article about how the medical community agreed that fatty foods are bad should be a cautionary tale of allowing policy to be set by majority opinion that does not reflect actual facts:

The notion that fatty foods shorten your life began as a hypothesis based on dubious assumptions and data; when scientists tried to confirm it they failed repeatedly. The evidence against Häagen-Dazs was nothing like the evidence against Marlboros.

It may seem bizarre that a surgeon general could go so wrong. After all, wasn’t it his job to express the scientific consensus? But that was the problem. Dr. Koop was expressing the consensus. He, like the architects of the federal “food pyramid” telling Americans what to eat, went wrong by listening to everyone else. He was caught in what social scientists call a cascade.

We like to think that people improve their judgment by putting their minds together, and sometimes they do. The studio audience at “Who Wants to Be a Millionaire” usually votes for the right answer. But suppose, instead of the audience members voting silently in unison, they voted out loud one after another. And suppose the first person gets it wrong.

If the second person isn’t sure of the answer, he’s liable to go along with the first person’s guess. By then, even if the third person suspects another answer is right, she’s more liable to go along just because she assumes the first two together know more than she does. Thus begins an “informational cascade” as one person after another assumes that the rest can’t all be wrong.

Because of this effect, groups are surprisingly prone to reach mistaken conclusions even when most of the people started out knowing better, according to the economists Sushil Bikhchandani, David Hirshleifer and Ivo Welch. If, say, 60 percent of a group’s members have been given information pointing them to the right answer (while the rest have information pointing to the wrong answer), there is still about a one-in-three chance that the group will cascade to a mistaken consensus.


I've been comfortable enough with my conclusions about the fighting to ignore the gradually accumulating conventional wisdom that we have been losing the war or the even more extreme position of some that we are doomed to lose in a quagmire.

Instead of a quagmire, we may be experiencing a cascade over Iraq.

And let's review all that inconvenient truth alarmist global warming crap in a decade or so.