Washington — ''We've nailed inflation, and it's the American consumer who is reaping the benefits.'' That was White House spokesman Larry Speakes' assessment last week of figures showing consumer prices rose at a seasonally adjusted annual rate of 4.1 percent in the first 11 months of this year and only 0.2 percent in November.
There is no question that the rate of inflation is down from the double-digit levels the United States experienced as recently as 1980, when consumer prices rose 12.4 percent or in 1979, when they climbed 13.3 percent.
A major recession, falling prices for oil and other commodities, and stiff competition from a flood of imported products all played a role in curbing upward pressure on prices, forecasters say.
But many economists say inflation is a difficult genie to keep bottled up, and that it is too early to claim a permanent victory.
Inflation ''is not the problem it was four years ago. We have made a lot of progress, but it is not dead,'' says David Wyss, a senior vice-president at Data Resources Inc., a forecasting firm.
''You can never completely nail inflation,'' adds Bernard Markstein III, a senior economist at Chase Econometrics, another forecasting firm. But progress has been made, he notes, and the outlook for consumer prices in 1985 ''is positive.''
And the chairman of the Federal Reserve Board, Paul Volcker, recently said: ''I think inflation is something you have to worry about all the time.''
While chances are small that inflation will zoom in 1985, the precise outlook for prices next year is a matter of dispute among economists. Inflation-rate forecasts range from zero to 7 percent.
Among 47 forecasters surveyed by ''Blue Chip Economic Indicators,'' a newsletter based in Sedona, Ariz., the consensus is that consumer prices will climb 4.5 percent next year, only slightly faster than the 4.3 percent pace predicted for all of 1984.
The uncertain outlook for the US dollar in world currency markets is the main reason forecasters' projections differ so widely. A rising dollar exerts downward pressure on prices in the US by lowering the cost of imported goods and putting pressure on domestic manufacturers to hold down prices. A falling dollar contributes to inflation by boosting the cost of imported goods and leaving US companies more freedom to jack up prices.
''The current lull in inflation will be short-lived if and when the dollar cracks in foreign exchange markets,'' warns Paul W. Boltz, vice-president of T. Rowe Price Associates Inc., an investment research firm.
Most forecasters expect the dollar to weaken only modestly in 1985, despite the Federal Reserve Board's announcement Friday that it was lowering its discount rate, the rate it charges member banks for borrowing, to 8 percent from 8.5 percent. Some analysts said the Fed's move would lead banks to lower the rates they charge for loans. In making the discount rate change the Fed cited the ''strength of the dollar internationally.''
Even if the inflation rate in 1985 were to remain unchanged from the 4.1 percent level posted so far this year, it would still be high by historical standards and troublesome for some consumers and for the stability of the economy as a whole.
In 1964, consumer prices rose only 1.2 percent. And as recently as 1971 President Richard Nixon imposed controls on wages and prices to deal with inflation that for the year as a whole ran at a 3.4 percent rate.
Even a low rate of inflation seriously erodes the purchasing power of individuals, like those receiving private pensions, whose incomes are not fully adjusted for inflation. For example, an inflation rate of 4 percent will halve the purchasing power of a dollar in 18 years.
Of course, inflation tends to help debtors, who often get to pay back their obligations with dollars that are worth less than those they borrowed.
Economists disagree on the amount of inflation with which a nation can safely live. ''We have found we can manage with 5 to 6 percent inflation,'' Mr. Markstein says, cautioning that ''some economists would object to that statement.'' Other economists say they believe that inflation tends to feed on itself, so even a moderate level is dangerous. A 2 to 3 percent inflation rate would ''be much better, but it is a little foolhardy to believe you can attain that in the near term without a major negative impact on the economy,'' Markstein says.
One of the most optimistic views of the inflation outlook comes from Edward Yardeni, senior vice-president of Prudential-Bache Securities Inc. He argues that the combination of downward pressure on oil prices, falling prices for other commodities, and moderate wage settlements by unionized workers all ''suggest that zero inflation is possible in 1985.''
A less cheery inflation outlook comes from David Hale, chief economist of Kemper Financial Services Inc., an investment advisory firm. He expects wages to climb in '85 as the economy continues to grow and unemployment falls. Already the prices for nonenergy services, which do not face import competition, are rising at a 6 percent annual rate, he notes.
So by late '85, prices ''should be poised to move'' to the 6 to 7 percent range, he says, if the world economy keeps improving.