SOME observers believe the 1990s will see "three-blocism." The United States will concentrate on North America and the Western Hemisphere; Japan will form the heart of a yen bloc in East Asia; and the European Community will be the center of a larger self-sustained European region. The conditions of the 1990s, it is argued, will make it impossible for broad multilateral cooperation - a public good of which the three main democratic industrialized areas of the world have been the primary trustees - to continue. With the end of the cold war, centrifugal forces among the democracies of Europe, North America, and Japan are likely to increase. The decline of Soviet power and the diminished appeal of communist ideology have removed the overarching common threat that was clear to public opinion in these democracies. During the cold war, the need to present a common front in the face of the common external threat helped to dampen economic conflicts. Now, interdependence continues to grow but the unifying security concern has been removed. With the absence of an external threat, the 1990s will see increased internal preoccupation within the regions that came together to form the Trilateral Commission in the early '70s. Europe will be preoccupied with its own integration as well as its relations with its neighbors. The US may turn inward to a domestic agenda of reform. Canada is grappling with fundamental issues of national unity. Japan, if rebuffed by Europe and the US, may halt its steps toward a greater global role in favor of a regional orientation. The separate-blocs vision of the world has a number of problems, however. For one thing, the trends in technology and economics run against a bloc view. Some political and economic forces will resist fragmentation of the international economy. Second, the idea of separate blocs runs counter to the nationalism in many nontrilateral countries concerned about maintaining an open international economy that provides access outside the region. These countries may develop an interest in trilateral cooperation r ather than separate blocs. Finally, the three-bloc view runs counter to the fact that, even after the cold war, America remains important to the security of both Europe and East Asia. So long as residual concerns remain about the outcome of the second Russian Revolution and the potential threat that the Soviet Union can pose to Western Europe, an American security guarantee remains valuable. Similarly, as long as Japan retains its peace Constitution yet lives in a region where other states, particularly China and the Soviet Union, retain nuclear weapons, a US security guarantee remains an important part of the geopolitical stability of that region as well. Another argument used in support of the view that trilateral cooperation, and thus broad global cooperation, will not continue relates to the turmoil associated with the rise or fall of great powers - in particular the presumed decline of the US. But this decline is greatly exaggerated. The American share of world product has held steady at roughly the same level of 23 percent from 1974 to 1990, after the wearing off of the "World War II effect" that meant an abnormally high US share in earlier postwar y ears. When the Trilateral Commission was formed 20 years ago, North America, the European Community, and Japan represented about 60 percent of the world economy. They still do today. The problems of the 1990s are to be understood less in terms of the rise or fall of great powers than in terms of the "diffusion of power." With the growth of economic interdependence, the proliferation of transnational actors, nationalism in weak states, the spread of technology, and the increasing number of issues that are both domestic and international, all great powers will be less able to use their traditional power resources to achieve their purposes. Since most of the resulting issues cannot be managed unilaterally, states will have a strong incentive to develop international cooperation. In sum, the need for trilateral cooperation in a wider global context is as great as, perhaps greater than ever. One of the problems of cooperation in the post-cold-war period will be finding ways to dramatize the benefits of cooperation, to represent the long-run self-interest of countries, and to escape the veto power of particular groups. Can leaders who understand the challenges make the arguments for international cooperation persuasive to public opinion in the trilateral democracies? An agenda for broad multilateral cooperation is critical for dramatizing the benefits of cooperation. This agenda ranges from substantive global problems - sustainable global economic growth and development, peaceful change in the declining Soviet empire, nonproliferation of advanced weapons technology, means to address environmental and other transnational global issues - to strengthening the global roles of Japan and a more integrated European Community, to key aspects of process, such as more attentio n to international institutions, and greater decision-sharing and burden-sharing. In the setting of the 1990s, groups favoring cooperation will need to reinforce each other by forming coalitions across national borders. The Trilateral Commission will need to think of itself as helping to formulate transnational coalitions that advance the common good.