Political risk is hard to manage because so much comes down to the personal choices of policymakers, whether prime ministers or heads of central banks.

If you thought the advent of the Internet, the spread of cheap and efficient information technology, and the growing fragmentation of the consumer market were all going to help smaller companies thrive at the expense of the slow-moving giants of the Fortune 500, apparently you were wrong.

Publishers, naturally, loathe used books and have developed strategies to depress the secondhand market. They bring out new, even more expensive editions of popular textbooks every three to four years, in a classic cycle of planned obsolescence.

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

The Internet has become a remarkable fount of economic and social innovation largely because it's been an archetypal level playing field, on which even sites with little or no money behind them - blogs, say, or Wikipedia - can become influential.

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.

The fact that industries wax and wane is a reality of any economic system that wants to remain dynamic and responsive to people's changing tastes.