But these concepts are difficult for many to swallow. Specialists like urologists, radiologists and oncologists, who see patients who are sick and dying from cancer, often resist the idea of doing less screening. General practitioners, who may agree with the new guidelines, worry about getting involved in long conversations with patients trying to explain why they might reconsider having a mammogram every year or a P.S.A. test at all. Some doctors fear lawsuits if they do not screen and a patient develops a fatal cancer. Patients often say they will take their chances with screening’s harms if a test can save their lives.

And comments like Dr. Brawley’s give rise to other questions as well. Is all this happening now because of worries over costs? And in any case, is all this simply an academic argument, since most doctors, faced with real patients, still suggest frequent screening and their patients agree?

President George W. Bush’s tax cuts had similar effects between 2001 and 2007: real growth in the absence of new investment.

over the course of the last century, net business investment atrophied while G.D.P. per capita increased spectacularly. And the source of that growth? Increased consumer spending, coupled with and amplified by government outlays.

Between 1900 and 2000, real gross domestic product per capita (the output of goods and services per person) grew more than 600 percent. Meanwhile, net business investment declined 70 percent as a share of G.D.P. What’s more, in 1900 almost all investment came from the private sector — from companies, not from government — whereas in 2000, most investment was either from government spending (out of tax revenues) or “residential investment,” which means consumer spending on housing, rather than business expenditure on plants, equipment and labor.

According to the Organization for Economic Cooperation and Development, retained corporate earnings that remain uninvested are now close to 8 percent of G.D.P., a staggering sum in view of the unemployment crisis we face.

So corporate profits do not drive economic growth — they’re just restless sums of surplus capital, ready to flood speculative markets at home and abroad. In the 1920s, they inflated the stock market bubble, and then caused the Great Crash. Since the Reagan revolution, these superfluous profits have fed corporate mergers and takeovers, driven the dot-com craze, financed the “shadow banking” system of hedge funds and securitized investment vehicles, fueled monetary meltdowns in every hemisphere and inflated the housing bubble.

we doubt the moral worth of consumer culture. Like the abstemious ant who scolds the feckless grasshopper as winter approaches, we think that saving is the right thing to do. Even as we shop with abandon, we feel that if only we could contain our unruly desires, we’d be committing ourselves to a better future. But we’re wrong.

Consumer spending is not only the key to economic recovery in the short term; it’s also necessary for balanced growth in the long term. If our goal is to repair our damaged economy, we should bank on consumer culture — and that entails a redistribution of income away from profits toward wages, enabled by tax policy and enforced by government spending.