THE relative decline of American power abroad is not an obvious case. In a year in which the former communist world has fallen further apart and behind, when a force organized by the American president rolled back an aggression in the Middle East, and an epoch-making event in the form of a Middle East peace conference is apparently going to happen, there is still ample evidence of American influence in the world.Yet there is a serious concern that, these spectacular events aside, the United States is going to be a weaker force in the world if it does not get its domestic house in better order. In the lead article in the fall issue of the Wilson Quarterly, on the fading fortunes of the so-called Establishment that forged a foreign policy for the US after 1945, Max Holland concludes: "The governing elite seems to have lost sight of the sources of American power. Rather than engagement being the natural consequence of a robust polity and economy, the satisfaction of exercising power appears to be a preoccupation in and of itself.... The Establishment remnant ... has failed to face up to the fact that America's economic house is in considerable disorder. Can a sustainable foreign policy be fashioned by any elite that ignores domestic realities?" This view is not an isolated one. Last week in Boston, John Macomber, the president of the Export-Import Bank, talked about the enormous trade opportunities opening up to America as a new era unfolds - in the Asian periphery, in Latin America, and especially in Eastern Europe. But he included in his remarks a warning: America's present position in the world depends as much on its economic prowess as any other factor. Noting the growing influence of both Japan and Germany around the world, he stressed th e importance of turning out better educated citizens at the secondary school level and of gearing the economy more toward savings and investment and away from its emphasis on personal consumption and consumer debt. "A nation's reputation abroad depends in part on the reputation of its goods that are sold abroad and the pool of capital available," he noted. This implies that American manufacturers must be competitive both in productivity and in the marketing of their products abroad. The need to improve productivity, and the degree to which this factor hangs on a better educational system, is also echoed by Paul Krugman, MIT economist, in his current book, The Age of Diminished Expectations. Krugman argues that the major reason the American economy has been slowing down in its performance over the past two decades is that its productivity has not kept pace with that of its main competitors abroad. And, while low productivity gains are the results of several factors, a main one is the inferior education of American workers. He argues that, just as a chain is as strong as its weakest link, the education of an individual person is more valuable to society at large than it is to that individual. Everyone in any organized system of work is held back by the performance of the weakest individual in the group. The danger in the present situation is that, after two generations of America's being the acknowledged world leader, not enough of its people realize that power will be measured in different ways in the coming generation. German influence, either directly or as a leading country in a more important European Community, and Japanese influence through that country's productivity in manufacturing and its financial strength will create new challenges. The US needs to learn how to share the responsibility for international decisionmaking in ways the cold war did not demand. But at the same time, in an era when military brinkmanship will hopefully not be called for, its public needs to understand better than it does how vital a resurgent American economy is to the nation's influence abroad. And that, in turn, leads one back to the issue of the present inadequate state of American education. One may hope that the coming year of political campaigning will address both issues - growth in the economy and better secondary education - substantively.