When the rich build bigger, they shift the frame of reference that shapes the demands of the near rich, who travel in the same social circles. Perhaps it's now the custom in those circles to host your daughter's wedding reception at home rather than in a hotel or country club. So the near rich feel they too need a house with a ballroom. And when they build bigger, they shift the frame of reference for the group just below them, and so on, all the way down.

No society has ever succeeded without a decent government.

No one could argue with a straight face that the couples getting married today are much happier just because their wedding celebrations cost three times as much as those in 1980. Bigger mansions and costlier parties are wasteful in the same sense that larger antlers on all bull elk are wasteful. The good news is that simple changes in the tax system can eliminate much of this waste without having to deny people the right to decide for themselves how best to spend their money.

Adam Smith's uncritically enthusiastic modern disciples portray his invisible hand theory as saying that market forces reliably harness selfish individuals to serve the common good. That's often true, but as Darwin recognized clearly, many traits that serve the interests of individual animals make life more difficult for larger groups.

We've long known that firms can pay higher wages if they spend less on workplace safety enhancement. Libertarians ask, "If a worker is willing to accept higher wages in return for his agreement to exercise greater caution while performing his job, why should the government prevent him from making that choice?" It's a rhetorically powerful question, yet it overlooks the fact that the agreement in question will have adverse effects on others.

If top marginal income tax rates are set too high, they discourage productive economic activity. In the limit, a top marginal income tax rate of 100 percent would mean that taxpayers would gain nothing from working harder or investing more. In contrast, a higher top marginal rate on consumption would actually encourage savings and investment. A top marginal consumption tax rate of 100 percent would simply mean that if a wealthy family spent an extra dollar, it would also owe an additional dollar of tax.

Many decry rising inequality because it makes those who've fallen behind feel impoverished. But it's done much more than cause hurt feelings. It has also raised the real cost to middle-income families of achieving many basic goals. The process begins with the completely unremarkable fact that top earners have been spending at a substantially higher rate than before. They've been building bigger mansions, staging more elaborate weddings and coming-of-age parties for their kids, buying more and better of everything.