Introduction / Klaus Knorr and Sidney Verba -- Problems of theory building and theory confirmation in international politics / Morton A. Kaplan -- Prospects for a general theory of international relations / Arthur Lee Burns -- Experimental games and bargaining theory / Thomas C. Schelling -- On the use of game models in theories of international relations / Richard E. Quandt -- The level-of-analysis problem in international relations / J. David Singer -- Assumptions of rationality and non-rationality in models of the international system / Sidney Verba -- Agraria and industria, two models of the international system / George Modelski -- International relations as a prismatic system / Fred W. Riggs -- The acute international crisis / Charles A. McClellenad -- International systems and international law / Stanley Hoffmann.