PEOPLE often remember the past with exaggerated fondness. Sometimes, however, important aspects of life really were better in the old days.

During the three decades after World War II, for example, incomes in the United States rose rapidly and at about the same rate  almost 3 percent a year  for people at all income levels. America had an economically vibrant middle class. Roads and bridges were well maintained, and impressive new infrastructure was being built. People were optimistic.

By contrast, during the last three decades the economy has grown much more slowly, and our infrastructure has fallen into grave disrepair. Most troubling, all significant income growth has been concentrated at the top of the scale. The share of total income going to the top 1 percent of earners, which stood at 8.9 percent in 1976, rose to 23.5 percent by 2007, but during the same period, the average inflation-adjusted hourly wage declined by more than 7 percent.

Yet many economists are reluctant to confront rising income inequality directly, saying that whether this trend is good or bad requires a value judgment that is best left to philosophers. But that disclaimer rings hollow. Economics, after all, was founded by moral philosophers, and links between the disciplines remain strong. So economists are well positioned to address this question, and the answer is very clear.