"If something can't go on forever, it won't."
--Herb Stein

WITH NEW HOME SALES DOWN 10.5 percent in February, and with home prices declining for the fourth month in a row, it's high time for a sober look at the consequences of a major housing correction. The Federal Reserve, Wall Street economists, and other observers of the U.S. economy are closely watching the housing market because it has been a key driver of economic growth over the past several years.

Roughly a quarter of the jobs created since the 2001 recession have been in construction, real estate, and mortgage finance. Even more important, consumers have withdrawn $2.5 trillion in equity from their homes during this time, spending as much as half of it and thus making a huge contribution to the growth the U.S. economy has enjoyed in recent years (consumer spending accounts for two-thirds of GDP).

But consumers cannot keep spending more than they make. Eventually, home prices will flatten, the flood of "cash out" refinancings will become a trickle, and consumer spending will slow, as will job creation in housing-related industries. The big question is this: Will the housing sector experience a soft landing and slow the economy or a hard landing that pushes us into recession?

Countless articles in the financial and popular press have now been devoted to the question of whether we are in a housing "bubble." It is a favorite topic of many liberal economists, columnists, and bloggers, who argue that President Bush's tax cuts and other policies have created a hollow and unsustainable economy. They are laying the groundwork to hang a housing bust around the necks of President Bush and congressional Republicans.

Economic observers on the right have been strangely silent on this debate. A few conservatives have argued that the record appreciation of home prices is justified by economic fundamentals. Others, who apparently slept through the 80 percent decline in the NASDAQ, don't believe bubbles are possible in a free market economy. Certainly most conservatives have an innate optimism about America and the resilience of its free market economy, and a strong and well-justified aversion to doomsayers. And naturally, the White House and congressional Republicans have no interest in highlighting the vulnerabilities of the economy.

Yet the concerns about unsustainable growth in consumer debt and home prices are not easily dismissed. A weakening housing market could transform what has been a virtuous cycle into a vicious one, substantially reducing economic growth during the next couple of years (and going into the 2008 election). If economic analysts on the right ignore this risk, they may be blindsided by a weaker economy. They will also be unprepared to answer those on the left who will blame tax cuts for what could be a painful unwinding of a credit bubble that, in fact, was fueled by a loose monetary policy from 2002 to 2004.

THE CRUX OF THE DEBATE IS HOUSE PRICES. If the inflated prices are justified by economic fundamentals and sustainable, then the 82 percent increase in mortgage debt since 2000 will probably turn out to be innocuous and the risks to the economy minimal. If, on the other hand, prices are out of whack, painful adjustments lie ahead.