Tough times have always lent themselves to nativist sentiments and closed-door policies. But in the case of highly skilled immigrants these policies are a recipe for stagnation.

From a social point of view, it's beneficial that homeownership encourages commitment to a given town or city. But, from an economic point of view, it's good for people to be able to leave places where there's less work and move to places where there's more.

If army ants are wandering around and they get lost, they start to follow a simple rule:Just do what the ant in front of you does. The ants eventually end up in a circle. There's this famous example of one that was 1,200 feet long and lasted for two days; the ants just kept marching around and around in a circle until they died.

Sometimes even a smart crowd will make a mistake.

The history of the Internet is, in part, a series of opportunities missed: the major record labels let Apple take over the digital-music business; Blockbuster refused to buy Netflix for a mere fifty million dollars; Excite turned down the chance to acquire Google for less than a million dollars.

The autocracies of the Arab world have been as economically destructive as they've been politically repressive.

Pop music thrives on repetition. You know a song's a hit when you've heard it so often that you'll be happy never to hear it again.