Popular as Keynesian fiscal policy may be, many economists are skeptical that it works. They argue that fine-tuning the economy is a virtually impossible task, and that fiscal-stimulus programs are usually too small, and arrive too late, to make a difference.

The financial crisis of 2008 was not caused by investment banks betting against the housing market in 2007. It was caused by the fact that too few investors - including all of the big investment banks - bet too heavily on the housing market in the years before 2007.

A general principle of good taxation is that similar jobs, and similar kinds of compensation, should be taxed the same way: otherwise, the government is effectively subsidizing some jobs over others.

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.

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.

Critics of consumer capitalism like to think that consumers are manipulated and controlled by those who seek to sell them things, but for the most part it's the other way around: companies must make what consumers want and deliver it at the lowest possible price.

If someone really wants my company's business, why shouldn't he be able to do everything he can - including paying me off - to get that business? Because bribery encourages people to make decisions based on the wrong criteria, which means in the business world that it distorts the efficient allocation of resources.