Consumers skimped on spending; companies limited hiring and investment.
Debts that seemed bearable quickly became burdensome. Firms and families "deleveraged."
Technological advance, an engine of growth in the 1990s, also seems to have faltered. Economist Robert Gordon of Northwestern University argues that the information technology boom is weakening.
A new study from the Federal Reserve provides some corroborating evidence. It finds that from 1995 to 2004, labor productivity - a measure of efficiency - in the nonfarm business sector increased 3.1 percent a year, with about half the gain coming from IT.
From 2004 to 2012, average annual gains dropped to 1.6 percent, with IT providing slightly more than a third.
Finally, demographics may hurt. As Americans age, they may restrain their spending.
In 2000, the 65-and-over population was 12 percent of the total. By 2025, it's projected to be nearly 19 percent.)
Their wants may not have decreased, but they don't know whether they will outlive their savings.
The decline in IRA and 401(k) retirement accounts - in many cases now reversed - could be repeated. Social Security and Medicare benefits could be cut.
These uncertainties breed caution.
Cheap credit addresses none of these problems directly and, indirectly, does so only weakly.
It can't erase the memories of the financial crisis. It can't create new technologies. It can't make older people younger.
At best, cheap money aided the housing recovery; at worst, it became a stock-market narcotic that can't be withdrawn painlessly.
Many countries face obstacles to growth that cheap money won't magically remove.
This raises a larger issue. Economists have been taught in graduate school that advances in their discipline make it possible to stabilize and, within broad boundaries, control economic activity.
But what if that's not so? The ferocious debates among economists indicate that the consensus has broken down.
Inevitably, there are better and worse policies, but in real time, it's not always clear which is which.
Business cycles endure. Market forces still dominate; the ability to subdue and reshape them remains limited.
Time, as much as policy, may promote recovery.