THE EXTENSIVE preparations for OPEC's 20th anniversary celebrations included the designing of a handsome monograph decorated with olive branches and the legend "Progress Through Solidarity." The anniversary bash itself, scheduled for Baghdad in November 1980, unfortunately had to be postponed when the host country, Iraq, chose to launch a war against Iran in September 1980. And "peace through solidarity" was not exactly in evidence at such regular OPEC meetings as did occur. "New, non-alphabetical seating arrangements had to be advised to prevent a physical clash between the delegates from Iran and Iraq," Dunkwart Rustow writes in his new book, Oil and Turmoil. "On one occasion, the Iranian representative bitterly complained that his country's oil minister, who would normally have attended, was instead a prisoner of the Iraqi forces."

Yet OPEC, at least so far, has survived all this, and so have OPEC prices. It is this kind of confusion about what OPEC is and isn't that has added extra fuel to what has turned into a running debate in the West: is the energy problem over, or is it only taking a rest?

Some argue that the problem is behind us, and advise us to watch for oil prices to tumble from $34 to $29 to $25 or even $20. Others in this camp say that energy no longer belongs on the national agenda, that the election of Ronald Reagan ended the problem.

The other side argues that the problem is cyclical, its intrusions depending upon the interaction of international affairs, the condition of the economy, and patterns of investment.

Who's up and who's down in the debate tends to correlate with the direction of prices on the Rotterdam spot market. Late last winter, as OPEC's internal strains became more obvious, the first party substantially increased its intellectual market share. In March, however, OPEC surprised many by holding its price, and market shares began to shift.

Which side is going to prove more correct? (Notice, I don't say "win," because some in the second camp don't want to see abrupt price hikes; rather, it's what they fear will happen). Events will deliver a verdict over the rest of this decade and into the next. To try to develop a reasonable picture requires the sorting through and arranging of a very large, diverse, and ill-fitting inventory. There is quite a lot to consider. Rustow takes on a big part of the puzzle in his new book: "the economic and the political, as well as . . . the historical and psychological dimensions."

The result is an intelligent, balanced, and quite well-written account. The earlier actions survey the Western impact on the Middle East, and, in particular, the evolution of American's relations with the Middle East and its oil. Rustow develops a thoughtful, sophisticated analysis of how oil prices have moved--a political crisis ignites panic buying on the world market, followed by an OPEC price consolidation. "OPEC's twentieth anniversary was indeed a joke, but the joke, for the time being, was on OPEC's customers," he writes. "There were no olive branches and no solidarity, but there was progress toward higher and higher prices --and the customers kept paying."

Rustow certainly belongs to the second party in the aforementioned debate, for he warns: "The myth dearest to optimistic Western observers is that any slowdown or temporary reversal of OPEC's fast-rising price curve might herald the beginning of the end."

Still, he argues that there is now enough diversity in the world oil market that more minor interruptions need not have the impact that they would have had a few years earlier. He focuses on what he sees as the three largest dangers: "a prolonged disruption of traffic through the Strait of Hormuz, a Soviet takeover in Iran, or a political upheaval in Saudi Arabia itself." The consequences could well be, he says, $100-a-barrel oil.

In the latter part of the book, Rustow turns his attention to the politics of the region and American policy therein. The jump is a little abrupt and the individual sections are not as well integrated with each other as they could have been. He offers the cautiously optimistic vision of a more stable region, and one that tolerates considerable diversity. Present events hardly make even that modest hope look practical. But then who could in 1973 have anticipated Sadat's initiative in 1977?

Considering America's energy future, in the meantime, however, it would be as unwise to count on regional stability as to count upon the permanent glut.