At Georgetown University here the other day, a highly respected international economist took a deep breath and made a prediction: The world will have to face -- and suffer through -- a major international economic crisis before President Reagan and his fellow heads of government take the steps they should have taken in advance to avoid a breakdown.

Gary C. Hufbauer, the first occupant of a new chair of international financial diplomacy named for the late Marcus Wallenberg, said that a crisis could be touched off by any one of three events: a collapse of the dollar, the final explosion of the Third World debt crisis in a way that "shakes the banking system" or the "insidious growth of trade barriers" that protect the dying industries.

"None of these outcomes is necessary, but on present evidence, each seems likely," Hufbauer said. He is a lawyer as well as economist, a graduate of Harvard University, a Ph.D. from Cambridge, and a veteran of the Treasury Department during the Carter years.

"I conclude that the world economy will need to suffer at least one dramatic shock before the major powers concentrate their attention on overhauling the international machinery," he said.

"Bert Lance taught Washington an unfortunate but enduring lesson: 'If it ain't broke, don't fix it.' Apparently, the international machinery needs to be visibly broke before it will be fixed."

Last month at the IMF/World Bank meeting in Seoul, Sir Jeremy Morse of Lloyds Bank made a similar point. In his Per Jacobsson lecture entitled "Do We Know Where We're Going?" Morse said that international cooperation is still strong whenever the major players are faced with a crisis.

"But away from the pressure of crisis, the story has been much less encouraging," said Morse in the understated British way.

It would be easy to dismiss Hufbauer's gloomy assessment as a bit of academic trivia, as likely to be wrong as right. But as I make the rounds here and abroad, in government and nongovernment circles, I hear echoes of Hufbauer's warnings, and for most of the same reasons. And most of them come back to a single issue: the distortions that have been superimposed on the world economy by the huge American budget deficit.

For example, the dangers implicit in the transition of the United States from a creditor nation to a debtor nation have been pointed out by persons of such diverse political interests and technical training as New York financier Peter Peterson, Commerce Secretary Malcolm Baldrige, Democratic Sens. Bill Bradley and Gary Hart, and Federal Reserve Board Chairman Paul A. Volcker.

At a private meeting of Japanese and American economists last weekend, one participant suggested that "the world hasn't yet caught up with the ultimate costs of four years of Reaganomics -- and won't until the crunch comes."

In announcing a new study of the Japanese-U.S. economic problems, C. Fred Bergsten of the Institute for International Economics said, "Japan and the United States, the two largest economies in the world, are moving in opposite directions at a fast rate -- we're becoming the big debtors and they're becoming the big creditors."

From a different perspective, a leading manufacturer of a small electrical appliances, venting his frustrations over competition from Europe and Japan, told an elite audience of Washington insiders, "The dollar is killing us, and if something isn't done about it, we're going to see the end of American manufacturing companies, and wind up with nothing but service businesses."

Downgrade that statement for its hyperbole, and you have a fairly accurate reflection of the dismay of the business community over the massive trade deficit. The problem is that the solution most business executives seek -- punitive legislation to tax or keep out imports -- doesn't do anything to deal with the main problem, the overvalued dollar.

The Reagan administration should get credit -- and Hufbauer gives it to them -- for taking some important first steps to deal with the three problems he outlines -- the dollar, Third World debt and protectionism. With Treasury Secretary James A. Baker III leading the way, the Group of Five major powers met at the Plaza Hotel in New York on Sept. 22, and pledged to intervene in foreign exchange markets to bring the dollar down.

A couple of weeks later in Seoul, Baker unveiled a plan to boost loans to Third World countries from multilateral development and commercial banks. Both steps were designed to help prick the bubble of support for trade protectionism. But does this mean anything, or as a responsible official of this administration whispered to me in the wake of the Seoul proposal, is it "Jim Baker's effort to buy time"? So far, banks have resisted Baker's efforts to get them to pour new money into the Third World. And the Reagan administration isn't ready yet to boost the lending power of the World Bank.

The G-5 initiative had a dramatic initial effect, especially in terms of the dollar-yen relationship. But Hufbauer said the Sept. 22 statement "was better at criticizing the foreign exchange markets than at coordinating underlying policy among the major powers. Perhaps policy coordination is not really necessary: A small dose of intervention may prick the dollar bubble, Sen. Robert J. Dole and his congressional allies may lead the United States back to the land of the balanced budget; Japan and Europe may stimulate their economies in a timely manner, and the bloated United States trade deficit may gradually diminish."

It would be grand if all of the complicated international economic troubles just took care of themselves. But they won't, and the real thrust of Hufbauer's message is that we can't rely on emergency patchwork repairs by five big central bankers and five big finance ministers.

Bradley and Hart have floated a number of proposals to improve the international financial system that go beyond the knee-jerk protectionism offered by many other Democrats during the past year. Hart, among other things, calls for a new Bretton Woods conference.

Bradley and Rep. Stan Lundine (D-N.Y.), as well as Sens. Patrick Moynihan (D-N.Y.) and Max Baucus (D-Mont.), have proposed legislation creating special intervention "reserve" pools to be used whenever net capital inflows seriously threaten to disrupt trade patterns. Among Hufbauer's proposals is one to make a world central bank out of the IMF, which is equally controversial.

Rep. Don J. Pease (D-Ohio) has introduced an omnibus bill that would give the president more than two years to alter macroeconomic policy to deal with a current account deficit amounting to 2.5 percent of gross national product -- or to justify its continuance to Congress. Failing that, he would be required to impose quotas or a surcharge to reduce the trade deficit.

These are serious ideas offered by thoughtful people, and they at least recognize one dimension of a problem -- currency fluctuations -- that, until very recently, the Reagan administration didn't even admit that the government could or should deal with.

Just as tough is the question of how to get tired industries to give way to newer ones. If AFL-CIO President Lane Kirkland's unyielding address to the AFL-CIO convention in Anaheim, Calif., last week is a guide, it won't be easy. In all the industrial nations, protection of agriculture increases rather than diminishes. Yet, as Hufbauer noted, the emerging NICs -- the newly industrializing countries -- are destined to be even stronger competitors. The World Bank estimates that, over the next 20 years, one billion new jobs must be created, more than 95 percent outside of the industrial nations.

These challenges to the existing order have to be met ahead of time, not after the fact. The thrust of Hufbauer's message is that they probably won't be. One can only hope that the breakdowns are repairable, not fatal.