Knopf, 570 pp, $50, hardcover

Perhaps thinking of money as the root of all evil is just one more luxury of living in a rich part of the world. It's comforting, certainly, because it implies that our common principles of tolerance and equality stem from some highly evolved moral nature that we possess. Yet Harvard political economist Benjamin M. Friedman's hefty new book, The Moral Consequences of Economic Growth, argues that socially progressive attitudes and institutions are, more often than not, founded on rising incomes.

Friedman finds some of his best evidence between the late 19th century and the Depression, when social reform in the U.S. ebbed and flowed with the state of economic expansion. The swamp into which America's economy fell in the 1880s, for instance, soon bred formalized racial segregation and Darwinist views about the expendability of the poor. In sharp contrast, the boom years between 1896 and 1913 saw the rise of antitrust campaigns and the NAACP, as well as laws allowing universal access to high-school education.

"Modernization creates problems; rising incomes offer the wherewithal to solve them, while fostering the spirit for doing so," Friedman sums up. At the same time, he says, with economic stagnation "the desire to turn back the clock and the tendency to seek out scapegoats are all too familiar."

The last point will indeed come as no surprise to readers of all political stripes. (How many historians would dispute the idea that Germany's poverty in the early 1930s helped open the door for the Nazis?) It's the previous assertion-of constant economic growth as a kind of precondition of social enlightenment-that will raise eyebrows in some quarters, especially when the author seems enthusiastic about the prospect of having the "developing" world's five billion people adopt our own consumerist ways. Even if you share Friedman's opinions in general, you must wonder how long the planet's air and water would bear the strain of such a huge proliferation of factories, highways, and landfills.

That said, Moral Consequences conveys the unquestionable sense that poverty breeds chaos, and that the best kind of society is open, egalitarian, and free. You may disagree on how the first should be cured and the second embraced, but reading this thoughtful, carefully shaded work will almost certainly force you to reexamine your own beliefs about the ways in which the material and the moral are bound together.