For most policymakers, deflation is the stuff of nightmares — scarier even than bank failures and stock market collapses. As the economy stumbled, deflation became Lords Voldemort and Sauron rolled into one.

In recent months, however, this economic supervillain seems to have lost its power to intimidate.

With growth reviving, many economists now believe that deflation is highly unlikely to materialize.

Another group suggests that deflation is not nearly as nefarious as often portrayed. Since falling prices are not generally associated with depression, we were wrong to be frightened in the first place.

Sadly, both of these reassuring premises are wrong. We should still be afraid of deflation.

First, the notion that deflation is a misunderstood and potentially benevolent economic force is only partially true. Supporters of this theory often cite research from the Federal Reserve Bank of Minneapolis, which showed that falling prices seldom coincide with depression.

Looking at data for 17 countries over more than a century, the Minneapolis Fed concluded that “nearly 90 percent of the episodes with deflation did not have depression.”

A swelling dollar can clearly be good news for shoppers as well as for those who are sitting on cash. Deflation is often a result of economic progress — productivity improvements that increase spending power. This was the friendly species of deflation caused by surging Chinese output from the 1990s onwards.

The current variety of deflationary pressure is far less benign. It stems not from efficiency savings but rather from weak demand. Worse still, it is accompanied by record levels of debt.

Despite frantic efforts to pay off loans, household debt is still around 130 percent of disposable income. This was precisely the combination that Irving Fisher warned about in his celebrated 1933 article on debt deflation.

Under these conditions, the rising real value of debts encourages households and businesses to sell their assets to pay down loans. As fire sales reduce asset prices — stocks and property — real net worth declines further. Output and employment decline, accelerating the slide in prices.

To add to the pain, real interest rates increase whether central bankers like it or not, discouraging borrowing and promoting even more savings.

“The more debtors pay, the more they owe,” Fisher wrote, since “the liquidation of debts cannot keep up with the fall of prices which it causes.”

But with the U.S. economy clawing its way out of recession, surely the danger has passed? Not quite. Prices are the ultimate economic straggler.

In Japan, for example, the country only started to experience falling prices roughly three years after the start of the recession in 1991. Wages didn’t start to fall until 1997. The United States could still follow Japan’s lead.

Downward pressures on prices in the United States continue to intensify, according to the latest research by Capital Economics. Core inflation may have held at a respectable 1.5 percent, but this is deceptive. U.S. goods inflation has defied gravity in part because of hefty increases in tobacco taxes over the past six months. A 28 percent increase in tobacco prices from a year ago is adding one percent to core goods inflation, according to Paul Ashworth of Capital Economics.

“Without this, core inflation would already be matching the lows reached at the end of 2003,” he says. The tobacco effect will soon fade.

Services inflation, meanwhile, has been very weak. Here the key factor has been weak rental prices, which account for about 40 percent of the total core index. Unemployment and foreclosure will continue to put relentless downward pressure on rents. Already the rental vacancy rate is at a record 10.6 percent.

So we are right to be afraid of deflation — very afraid. It still has the potential to sap energy from the American economy for years to come.

The Federal Reserve is preparing to lay down its unorthodox monetary policy instruments. But it may have to dig deep into its tool box before too long if deflation takes hold.