The 39th session of the United Nations General Assembly formally opened yesterday against the backdrop of a world that increasingly seeks international solutions - to such pressing global challenges as a spiraling arms race, hunger, illiteracy, and, in many third-world nations, rapid population growth.
In that regard, it can only be regretted that the United Nations itself has too often been relegated to the sidelines in the resolution of these same challenges, even while other multilateral organizations - such as the World Bank and the International Monetary Fund, the European Common Market, and the General Agreement on Tariffs and Trade, for all their own organizational problems - have moved to center stage on the world scene.
Indeed, as the world's problems have become more economic in orientation - stemming in part from the oil price hike shocks of the 1970s, the severity of the recent recession, and the global debt problem - bilateral and multilateral responses by trade and economics ministers and economic organizations have tended to gain primacy over traditional diplomacy.
That is not to disparage the severity of political and military conflicts, such as those in Afghanistan, Central America, or the Middle East. Nor is it to play down the efforts of economic ministers or economic-oriented organizations. But it is to take note of the extent to which the sense of optimism and accomplishment about dealing with major conflicts that characterized the early years of the United Nations have been replaced by much public indifference and, worse, cynicism. As observed by UN Secretary-General Javier Perez de Cuellar in his new annual report, largely because the members of the UN are divided, ''the public generally concludes that there is something wrong with the United Nations and with the concept of internationalism.''
''Without the safety net'' which the international concept of the UN provides , his report concludes, ''the world would certainly be a much more dangerous and disorderly place.''
In fairness, many of the problems of the UN today must be put at the organization's own doorstep. In some instances, majorities of third-world nations have tended to ''gang up'' on the industrial nations in debate, if not through actual committee or General Assembly resolutions. Or so the perception has grown in the West. It takes little imagination to recognize that such a heavy dosage of rhetorical indignation directed against the West - justified or not - can very quickly produce a backlash, as has happened in the United States, where there has been some falloff in support for the UN.
The task for the world community could not be more clear: It is to make the United Nations work even better in a world of increasing economic and political interdependence. The UN still has an important role to play: in its ongoing effort to overcome world hunger and poverty, in encouraging contacts among nations. It should not be overlooked, for example, that Soviet Foreign Minister Gromyko will be meeting President Reagan in the course of the Soviet official's trip to the UN next week.
What is called for is leadership and, more specifically, support for the efforts of Mr. Perez de Cuellar and other UN officials as they grapple with such issues as the Mideast. Far too often in this century the world community has tended to create international organizations and then let them fade into a vestige of bureaucracy. That happened after World War I. And that is happening now. What is needed is a renewal of the sense of practical accomplishment and, yes, mission, that marked the early years of the United Nations.