Lower oil prices won't, by themselves, topple the mullahs in Iran. But it's significant that, historically, when oil prices have been low, Iranian reformers have been ascendant and radicals relatively subdued, and vice versa when prices have been high.

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.

The smartest groups, then, are made up of people with diverse perspectives who are able to stay independent of each other.

The truth is that the United States doesn't need, and shouldn't have, a debt ceiling. Every other democratic country, with the exception of Denmark, does fine without one.

I think there is clearly a connection between free time and procrastination. The more you have of the former, all things being equal, the more likely you are to procrastinate.

We assume that good-looking people are smarter and more effective than they really are, and that homely people are the reverse.

I started in business journalism from the outside, so when I started writing about markets and business, I was struck by the fact that markets seemed to work well even though people are often irrational, lack good information and are not perfect in the way they think about decisions.