Speculators get a bad rap. In the popular imagination they're greedy, heedless, and amoral, adept at price manipulations and dirty tricks. In reality, they often play a key role in making markets run smoothly.

Companies have long gathered data to break down their customer base into specific segments. Now political parties have become adept at micro-targeting, too, using data on shopping habits, leisure activities, voting histories, charity donations, and so on, in order to pinpoint likely supporters and the type of appeal most likely to win them over.

In industries where a lot of competitors are selling the same product - mangoes, gasoline, DVD players - price is the easiest way to distinguish yourself. The hope is that if you cut prices enough you can increase your market share, and even your profits. But this works only if your competitors won't, or can't, follow suit.

In terms of productivity - that is, how much a worker produces in an hour - there's little difference between the U.S., France, and Germany. But since more people work in America, and since they work so many more hours, Americans create more wealth.

As technology improves, on-screen avatars look more and more like real people. When they start looking too real, though, we pull away. These almost-humans aren't quite right; they look creepy, like zombies.

In order to work well, markets need a basic level of trust.

The problem is that groups are only smart when the people in them are as independent as possible. This is the paradox of the wisdom of crowds.