THE RISE AND FALL OF THE GREAT POWERS. Economic Change and Military Conflict from 1500 to 2000. By Paul Kennedy. Illustrated with maps, tables and charts. 677 pages. Random House. $24.95.
AS the Yale historian Paul Kennedy explains at the outset of his new study, ''The Rise and Fall of the Great Powers: Economic Change and Military Conflict from 1500 to 2000'': From the Renaissance to the present, nations have prospered depending on the strategic use of their wealth in time of war as well as on their strength relative to other nations in the decades preceding a particular conflict.
In the lengthy history that follows, Professor Kennedy demonstrates, among many other things, that nations rising to supremacy by winning wars tend to get overextended in a way that undermines the source of their wealth. The 17th-century collapse of the Hapsburg Empire is one obvious example he cites. The decline of Victorian Great Britain is another.
This will seem self-evident to anyone who has given the least thought to European history. The author himself admits as much when he writes in conclusion that it is ''unsurprising'' and ''has been said many times before'' that the ''uneven pace of economic growth has had crucial long-term impacts upon the relative military power and strategical position of the members of the states system.'' So why is it necessary for him to write over 500 pages on the subject, not counting his extensive notes and bibliography?
Although it took this reader a while to get a handle on what Professor Kennedy is up to here, there do turn out to be a number of compelling reasons for the project. First, he informs us, the field has simply not been adequately explored. As he discovered when he began giving trial-run talks about some of the book's themes: ''Precisely because neither economic historians nor military historians had entered this field, the story itself had simply suffered from neglect.''
Second, his strategic-economic approach provides him with the context for a shapely narrative. This is no insignificant thing, considering the way so many histories meander aimlessly. Professor Kennedy not only exploits his framework eloquently, he also makes use of it to dig deeper and explore the historical contexts in which some ''power centers'' prospered - for instance, why in the 16th century the cluster of states in west-central Europe rose to economic and strategic pre-eminence while such imposing Oriental empires as Ming China or Tokugawa Japan did not.
But the most commanding purpose of his project - the figurative other shoe that we wait for to drop throughout the detailed narrative - is the lesson he draws from 15 centuries of statecraft to apply to the present scene. For given the United States' extensive global commitments and its declining rate of growth relative to other powers in the world, one is bound to think if not of the Roman Empire then perhaps of imperial Spain in the 17th century and most decidedly of Victorian Great Britain.
Professor Kennedy, too, thinks of these fallen empires in his final chapter, ''To the Twenty-First Century,'' wherein he accepts the division of the world into five economic clusters that Richard Nixon once proposed -Western Europe, Japan and China as well as the U.S.S.R. and the United States. But surprisingly he isn't so pessimistic.
Western Europe must surmount its many divisions to realize its enormous potential, to reduce to a single sentence one phase of Professor Kennedy's lengthy concluding analysis. Japan, while rich and getting richer, faces the dilemma of whether it will someday have to build a military machine to defend its wealth.
China, while ''simultaneously the poorest of the major Powers and probably the least well placed strategically,'' seems to be ''evolving a grand strategy altogether more coherent and forward-looking than that which prevails in Moscow, Washington, or Tokyo, not to mention Western Europe.'' The Soviet Union faces cruel non-Marxist contradictions that are undermining its already weakening role in the world.
As for the United States, to which Professor Kennedy devotes the longest and most ambiguous analysis (partly because he is closer to this country; partly because its problems are more difficult to read): it is now on the horns of the dilemma that this book was written to investigate.
''Simply because it is the global superpower, with far more extensive military commitments than a regional Power like Japan or West Germany, it requires much larger defense forces - in just the same way as imperial Spain felt it needed a far larger army than its contemporaries and Victorian Britain insisted upon a much bigger navy than any other country.'' Yet ''a very heavy investment in armaments, while bringing greater security in the short term, may so erode the commercial competitiveness of the American economy that the nation will be less secure in the long term.''
In the long run, then, the United States must decline, Professor Kennedy concludes. But this decline need not be as steep as past empires faced; ''it may be argued that the geographical extent, population and natural resources of the United States suggest that it ought to possess perhaps 16 or 18 percent of the world's wealth and power'' instead of the 40 percent or more it controlled in 1945.
He concludes: ''The task facing American statesmen over the next decades, therefore, is to recognize that broad trends are under way, and that there is a need to 'manage' affairs so that the relative erosion of the United States' position takes place slowly and smoothly, and is not accelerated by policies which bring merely short-term advantage but longer-term disadvantage.''
Some will call this conclusion defeatism and others will call it whistling happily in the dark. Whatever it may be, it demonstrates that while the body of this text may be for the occasional browser of good historical writing, its final section is for everyone concerned with the contemporary political scene.
Photo of Paul Kennedy (T. Charles Erickson)