The third world, with three-quarters of the world's population but only a small share of world trade and an Everest of debts, has decided on a new tack to lessen its plight:
It has opted to knock rather than pound on the doors of the rich nations.
The new rationale is that perhaps conciliation rather than confrontation would persuade the wealthier nations to open up those doors and share more of their goods.
Gone for the moment at least are absolute demands for ''a new international economic order'' with radical changes in the institutions of the existing world financial and trade system.
Yet the overriding question in Belgrade, where representatives of practically every country in the world are currently attending the sixth United Nations Conference on Trade and Development (UNCTAD VI), is this:
Will the more moderate tone of the third world and its stress on shorter-term , more pragmatic economic proposals prompt the ''have'' countries to be more responsive to the needs of the ''have-nots''?
The answer, gleaned from experts who follow the situation closely, is ''unlikely.''
The danger, development specialists say, is that the third world, if rebuffed after moderating its stance, may revert to its earlier militancy.
A rather different view is that, since the third world does not have the political leverage to change the world economic situation, it will simply have to live with its disappointments.
One reason the ''have'' countries may not be so forthcoming at UNCTAD VI as the ''have-not'' nations would like is that the major industrialized powers are not in good enough economic shape to help out. The Western industrialized nations have more than 32 million workers unemployed, and the feeling is that in the middle of worldwide economic recession, charity begins at home.
As a result, a third world proposal at UNCTAD VI to raise minimally $80 billion more in aid to help rescue hard-pressed developing nations is expected to go nowhere.
Another and perhaps more potent reason most third world demands are likely to go unmet is the stance of the most influential rich nation: the United States. The US is not only keeping a very low profile at the UNCTAD conference, feeling such a forum is not the place to make substantive global economic changes; but also it seriously considered not sending any delegation at all to Belgrade.
The US position, according to these specialists, can be summed up this way: The US is already doing what it can to help the poor countries, and the rest of the world must now await the economic recovery that the US has started.
According to John W. Sewell, president of the Overseas Development Council in Washington, UNCTAD VI will achieve very little, if anything. ''There will be no quick fixes and no new institutions,'' he says. No substantive changes are expected on the issues that most third world countries are exercised about.
Lawrence B. Krause, an international economist at the Brookings Institution in Washington, also doubts whether UNCTAD will produce results. He sees it as the wrong mechanism to handle significant issues, since economic strategies are subordinated there to political statements.
If third world delegates are to go home empty-handed June 30 - after arriving with proposals to put the world economy on a firmer, and for them fairer, footing - then UNCTAD VI's track record would be no better than that of UNCTAD V , which was held in Manila four years ago.
Those unresolved concerns then are precisely the problems facing UNCTAD delegates today. These were and still are:
* Stabilizing sagging prices of most raw commodities through a buffer system of stockpiles and a common fund to help prop up world prices of commodities. Countries like Tanzania find that because of sagging commodity prices they must sell far more exports to buy the same amount of imported manufactured goods they bought a few years ago. But there are signs now of a resurgence in commodity prices.
* Restructuring third world debts of around $700 billion - or 10 times the level of a decade ago - through some form of debt relief such as stretching out the payment of some loans and writing off others. At present, the external debt service payments of Mexico, Argentina, Brazil, and Chile exceed their total earnings from exported goods and services.
* Further opening of industrialized nations' markets to third world products by lowering protectionist trade barriers.
* Guaranteeing developing nations a greater voice in economic policy decisions.
Some economists suggest that it is unrealistic to expect any changes until the world economy recovers. The logic is that a stronger world economy will increase the West's industrial production. This, in turn, would increase demand for the exports of raw materials from developing countries that would have the effect of boosting their commodity prices. The surge in export earnings would then assist the third world in reducing the debt burdens that eat up such a vast proportion of their foreign exchange earnings.
At the same time, as the Williamsburg summit of the seven major industrialized nations underscored, there is a recognition that if the burgeoning world economic recovery is to take hold, the richer nations will have to help cut the mounting debts of the poorer nations and roll back protectionist barriers.
In recent months, the US reversed its earlier opposition and joined forces with its Western allies in agreeing with individual donor countries to increase substantially their quota contributions to the International Monetary Fund.
What Williamsburg failed to do was to provide any commitment to replenish the International Development Agency, an arm of the World Bank, which provides easy terms for loans to the world's very poor countries. These are the countries least likely to benefit from a pickup in world trade. And it is these countries that UNCTAD VI insists are in most need of help.