Another set of future gains, especially for lesser-skilled workers, may come as computers become easier to handle for people with rudimentary skill. Not everyone can work fruitfully with computers now. There is a generation gap when it comes to manipulating electronic devices, and many relevant tasks require knowledge of programming or, more ambitiously, the entrepreneurial skill of creating a start-up. That, in a nutshell, is how our dynamic sector has concentrated its gains among a relatively small number of employees, thus leading to more income inequality.

This particular type of inequality may very well change. As the previous generation retires from the work force, many more people will have grown up with intimate knowledge of computers. And over time, it may become easier to work with computers just by talking to them. As computer-human interfaces become simpler and easier to manage, that may raise the relative return to less-skilled labor.

The future may also extend a growing category of employment, namely workers who team up with smart robots that require human assistance. Perhaps a smart robot will perform some of the current functions of a factory worker, while the human companion will do what the robot cannot, such as deal with a system breakdown or call a supervisor. Such jobs would require versatility and flexible reasoning, a bit like some of the old manufacturing jobs, but not necessarily a lot of high-powered technical training, again because of the greater ease of the human-computer interface. That too could raise the returns to many relatively unskilled workers.

A more universal expertise with information technology also might reverse some of the income inequalities that stem from finance. For instance, the returns from high-frequency trading were higher a few years ago, in part because few firms used it; now many firms can trade at very high speeds. It remains to be seen whether similar developments will lower hedge fund returns, but again it is possible to imagine a future in which many of the best investment and trading techniques are very widely copied and thus cease to be especially profitable.

A final set of forces to reverse growing inequality stem from the emerging economies, most of all China. Perhaps we are living in a temporary intermediate period when America and many other developed nations bear a lot of the costs of Chinese economic development without yet getting many of the potential benefits. For instance, China and other emerging nations are already rich enough to bid up commodity prices and large enough to drive down the wages of a lot of American middle-class workers, especially in manufacturing. Yet while these emerging economies are keeping down the costs of manufactured goods for American consumers, they are not yet innovative enough to send us many fantastic new products, the way that the United States sends a stream of new products to British or French consumers, to their benefit.