THE LATEST COMMUNIQUE on inflation bears a particularly melancholy message: The dollar is worth just half as much today as in 1967, when the great rise in prices began. Perhaps the most useful way to mark the occasion is to try to recapitulate the circumstances that have caused this decline.

There have been similar drops in the dollar's value before, but they have always been associated directly with wars. By the end of the Korean War, the dollar was worth barely half as much as at the beginning of World War II. But from the early 1950s to the late 1960s, there was relative stability. The present troubles started, once again, with a war. The Johnson administration delayed too long in raising taxes to pay for Vietnam, and the Nixon admnistration cooperated eagerly with a Democratic Congress in repealing those taxes much too soon. But that was only the beginning.

The United States underestimated the consequences of the devaluation of the dollar in 1971. Other countries were growing rapidly richer, and their people were demanding higher standards of living. A series of bad harvests abroad in 1972 and 1973 led to unprecedented purchases of American grain for export, far beyond anything that this country had anticipated. That pushed up food prices. The great leap in oil prices began in 1973.

Simultaneously, the Nixon administration was preparing for re-election. It has been customary for an administration to try to keep up the economy for an election year, but in this respect as in others, Mr. Nixon outdid his predeccessors. Using the controls to postpone the impact on prices, he deliberately speeded up the economy - creating, you might say, the economic equivalent of wartime - to induce a temporary burst of prosperity. The following year, as many industries overshot their capacities to produce, all sorts of familiar commodities ran short here and there - gasoline, beef, toilet paper. The controls collapsed and, in 1974 alone, prices rose 12 percent. The economy tipped into a severe recession.

Since then the inflation has been mainly circular, as people try to keep their wages and profits up to prices that keep trotting ahead of them. The Carter administration has probably speeded up the race by running large deficits at a time when the economy is, once again, very close to full capacity. Now, ominously, the country is about to feel the force of another wave of inflation from the international markets. The decline of the dollar's value over the past year is going to mean that all imported goods will cost more, and OPEC is about to raise the price of oil again.

Running through these mistakes and misfortunes, you can trace several persistent errors. Americans have been slow to recognize that the structure of the labor force is changing in ways that raise the normal levels of unemployment. As succesive adminstrations struggled to reduce unemployment to the traditional rates of the past, they were rewarded mainly with more inflation. There has been a consistent tendency to overestimate the speed at which the economy can be made to expand. There has been a similarly consistent tendency to underestimate the rising financial and industrial power of Europe and Japan. If you can speak of a single cause of the long inflation, it is the reluctance of Americans to come to terms with the truth that the long boom of the 1960s is over and that the American domination of the world economy is ending.

Mr. Carter is now embarked on a strategy for slowing down the inflation and distributing its costs as widely and fairly as possible. It is a high-minded and good-hearted policy, but as a matter of politics it will be a disheartening one to maintain. There are further reverses coming. It is a strategy that can only work slowly, and never completely. But the only alternative - a prolonged and deep recession - would be much more painful and only marginally more effective in stabilizing prices. If inflation continues at the present rate, incidentally, the dollar will fall to half of its present value by 1985.