THEORY: Efficient Equality

The gap that separates the poor from the affluent has been a prime source of tension, division and violence in American life. A critical challenge for politicians and economists alike has long been to try to find a way to soften the harsher injustices of U.S. capitalism without crippling it. That is the central dilemma that Economist Arthur Okun faces in an eminently readable, slim new book, Equality and Efficiency: The Big Tradeoff, published by the Brookings Institution in Washington.

Okun, a senior fellow at Brookings, an influential liberal Democrat and a member of TIME's Board of Economists, questions the...