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.

No society has ever succeeded without a decent government.

The most common mistake we make as teachers is attempting to tell our students too much.

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.

It is no exaggeration to say that rising inequality has driven many of the 99 percent into a financial ditch. It also helped spawn the housing bubble that gave us the financial crisis of 2008, the lingering effects of which have forced many OWS protesters to try to launch their careers in by far the most inhospitable labor market we've seen since the Great Depression. Even those recent graduates who manage to find jobs will suffer a lifelong penalty in reduced wages.

Unless we can act collectively, there would be no way to defend ourselves, no way to define or enforce property rights. We couldn't curb congestion or pollution or build and maintain public infrastructure.

For the three decades after WWII, incomes grew at about 3 percent a year for people up and down the income ladder, but since then most income growth has occurred among the top quintile. And among that group, most of the income growth has occurred among the top 5 percent. The pattern repeats itself all the way up. Most of the growth among the top 5 percent has been among the top 1 percent, and most of the growth among that group has been among the top one-tenth of one percent.