In the three centuries or so since the modern international system began flo take on its present shape, its component members have come together in a wide variety of organizations, for a wide variety of purposes. Those who act on behalf of the nations have turned to international organizations to oversee peace settlements, to strengthen their collective defense capacity, to mediate conflicts between themselves, to discourage interference from the outside, to harmonize their trade relations, to supervise international waterways, to accelerate the production of food, to codify diplomatic practice, and to formalize legal proceedings. Some organizations are established primarily for the neutral purpose of making coexistence possible, others for the more affirmative purposes of positive cooperation. Some have been directed toward the modification of the system, others toward the preservation of its status quo.
J. David Singer is professor of political science at the University of Michigan, Ann Arbor. Michael Wallace is assistant professor of political science at the University of British Columbia, Vancouver, Canada. This article is part of a larger study of the correlates of international war, based at the University of Michigan and supported by the Carnegie endowment and the National Science Foundation. The original draft was prepared while the first author was a visiting scholar at the Carnegie Endowment for International Peace in Geneva and the coauthor was the recipient of a Canada Council graduate fellowship. To both institutions we want to express our respective thanks. Of considerable help in the acquisition and codification of our data were David Handley, Joan Jensen, and James Connolly; Urs Luterbacher and Larry Arnold conducted the data analyses. An earlier version was presented at the February 1968 meeting of the Carnegie endowment's “Groupe d'6tude sur l'organisation Internationale” in Nice, and we are extremely grateful for the frank and penetrating comments offered by our colleagues on that occasion; a particularly detailed and valuable critique was prepared by John Burton.