theory for international law, international lawyers seek both theory and methodology. 2 As a sult, international legal scholarship too often combines careful doctrinal description--here is what the law is--with unfounded prescription: here is what the law should be. This scholarship often lacks any persuasively articulated connection between description and prescription, undermining the prescription. International legal scholarship lacks a progressive research program. 3 In response, several international law scholars have turned to other disciplines. Some such as Kenneth Abbott and Anne-Marie Slaughter have led the way into international political theory, including international political economy, and have begun a thoughtful arbitrage. 4 At the same time, the international political scientists were engaged in their own rationalist arbitrage, borrowing from various components of economic theory and game theory. While there are valuable tools to be borrowed from political scientists, our focus here is on the rationalist tools that are in turn largely borrowed from economics, and in several cases from law and economics Economics is the study of rational choice. As such, it plays a leading role in evaluating the effects of rational maximizing behavior under conditions of scarcity. Economics enjoys a comparative advantage over other disciplines in rationality-based analysis, simply because this nalysis is central to economics, and economics has developed this analysis extensively. The development has largely been in the mathematical realm, the so-called"blackboard economics. 5 However, at this point in the development of economics--and of international law--the more mathematical models do not seem to engage the core issues of international law. Economics as practiced by lawyer-economists often involves complex cost-benefit analysis. This approach is often useful, but has important limitations due to problems of administrability, commensurability and interpersonal comparison of utility lowever, the more promising economic methodologies, in terms of their capacity to generate a progressive research program that might usefully address persistent international law problems, are not those that teach us to balance the costs and benefits of any particular policy, but For one account of this search, see Anne-Marie Slaughter Burley, International Law and International Relations Theory: A Dual Agenda, 87 AM. J. INT'L L. 205(1993) 3 See Imre Lakatos, Falsification and the Methodology of scientific Research Programmes, in CRITICISM AND THE GROWTH OF KNOWLEDGE 91(Imre Lakatos Alan Musgrave eds, 1970); Jason S Johnston, Law, Economics and Post-Realist Explanation, 24 L. Soc Y REV. 1217(1990) 4 See, e. g Kenneth w. Abbott, Modern international Relations Theory: A Prospectus for International Lawyers, 14 YALE J. INTL L 335(1989); Slaughter, supra note 2 5 See, e.g., Ronald Coase, The Institutional Structure of Production, 82 AM. ECoN. REV 3,719(1992) My remarks have sometimes been interpreted as implying that I am hostile to the mathematization of economic theory. This is untrue. Indeed, once we begin to uncover the real factors affecting the performance of the economic system, the complicated inter relations between them will clearly necessitate a mathematical treatment, as in the natural sciences, and economists like myself, who write in prose, will take their bow. May thistheory for international law, international lawyers seek both theory and methodology.2 As a result, international legal scholarship too often combines careful doctrinal description--here is what the law is--with unfounded prescription: here is what the law should be. This scholarship often lacks any persuasively articulated connection between description and prescription, undermining the prescription. International legal scholarship lacks a progressive research program.3 In response, several international law scholars have turned to other disciplines. Some, such as Kenneth Abbott and Anne-Marie Slaughter have led the way into international political theory, including international political economy, and have begun a thoughtful arbitrage.4 At the same time, the international political scientists were engaged in their own rationalist arbitrage, borrowing from various components of economic theory and game theory. While there are valuable tools to be borrowed from political scientists, our focus here is on the rationalist tools that are in turn largely borrowed from economics, and in several cases from law and economics. Economics is the study of rational choice. As such, it plays a leading role in evaluating the effects of rational maximizing behavior under conditions of scarcity. Economics enjoys a comparative advantage over other disciplines in rationality-based analysis, simply because this analysis is central to economics, and economics has developed this analysis extensively. The development has largely been in the mathematical realm, the so-called “blackboard economics.”5 However, at this point in the development of economics--and of international law--the more mathematical models do not seem to engage the core issues of international law. Economics as practiced by lawyer-economists often involves complex cost-benefit analysis. This approach is often useful, but has important limitations due to problems of administrability, commensurability and interpersonal comparison of utility. However, the more promising economic methodologies, in terms of their capacity to generate a progressive research program that might usefully address persistent international law problems, are not those that teach us to balance the costs and benefits of any particular policy, but 2 For one account of this search, see Anne-Marie Slaughter Burley, International Law and International Relations Theory: A Dual Agenda, 87 AM. J. INT’L L. 205 (1993). 3 See Imre Lakatos, Falsification and the Methodology of Scientific Research Programmes, in CRITICISM AND THE GROWTH OF KNOWLEDGE 91 (Imre Lakatos & Alan Musgrave eds., 1970); Jason S. Johnston, Law, Economics and Post-Realist Explanation, 24 L. & SOC' Y REV. 1217 (1990). 4 See, e.g., Kenneth W. Abbott, Modern International Relations Theory: A Prospectus for International Lawyers, 14 YALE J. INT’L L. 335 (1989); Slaughter, supra note 2. 5 See, e.g., Ronald Coase, The Institutional Structure of Production, 82 AM. ECON. REV. 713, 719 (1992): My remarks have sometimes been interpreted as implying that I am hostile to the mathematization of economic theory. This is untrue. Indeed, once we begin to uncover the real factors affecting the performance of the economic system, the complicated inter￾relations between them will clearly necessitate a mathematical treatment, as in the natural sciences, and economists like myself, who write in prose, will take their bow. May this period soon come. 2