Sometimes even a smart crowd will make a mistake.

Bubbles and crashes are textbook examples of collective decision making gone wrong. In a bubble, all of the conditions that make groups intelligent - independence, diversity, private judgement-disappear.

Businesses that have gone through an episode of hyperinflation become understandably alert to the threat of it: at the first hint of inflation, they're likely to increase prices, since they've learned that if they don't, and inflation hits, their businesses will be wrecked.

If you work for Google or Apple, stock options give you a chance to share in the increasing value of the company. In the N.F.L., nothing like this happens; the players, though rich, are just working stiffs like the rest of us.

Defense contractors are able to reap tremendous profits while rarely confronting the risks for which those profits are supposed to be the reward.

In effect, dividing your attention means that neither (or none) of the things you're working on is really getting the full effect of your intelligence, and that it in the end takes you longer than it would if you did one thing at a time.

When Americans think of college these days, the first word that often comes to mind is 'debt.' And from 'debt' it's just a short hop to other unpleasant words, like 'payola,' 'kickback,' and 'bribery.'