WHEN LUCK RUNS OUT

The US economy has been helped by falling oil prices. But now they are rising, inflation could become a problem once again. The Federal Reserve's job of containing increases in inflation and nominal demand will be tricky. It may prove very difficult, for example, to curb demand without causing a stock market collapse and an unmanageable decline in demand, as household savings rise and corporate investment is cut. With continued weakness of economies elsewhere, the Fed may be able to risk delaying the tightening for a while. But that time is likely to come. It is one thing to enjoy the blessings of luck; another to rely on its lasting forever.