When John Harsanyi came to Stanford University as a candidate for the Ph.D., I asked him why he was bothering, since it was most un likely that he had anything to learn from us. He was already a known scho lar; in addition to some papers in economics, the first two papers in this vol ume had already been published and had dazzled me by their originality and their combination of philosophical insight and technical competence. However, I am very glad I did not discourage him; whether he learned any thing worthwhile I don't know, but we all learned much from him on the foundations of the theory of games and specifically on the outcome of bar gaining. The central focus of Harsanyi's work has continued to be in the theory of games, but especially on the foundations and conceptual problems. The theory of games, properly understood, is a very broad approach to social interaction based on individually rational behavior, and it connects closely with fundamental methodological and substantive issues in social science and in ethics. An indication of the range of Harsanyi's interest in game the ory can be found in the first paper of Part B -though in fact his owncontri butions are much broader-and in the second paper the applications to the methodology of social science. The remaining papers in that section show more specifically the richness of game theory in specific applications.

Inhalt
A / Ethics and Welfare Economics.- I. Cardinal Utility in Welfare Economics and in the Theory of Risk-Taking.- II. Cardinal Welfare, Individualistic Ethics, and Interpersonal Comparisons of Utility.- III. Ethics in Terms of Hypothetical Imperatives.- IV. Can the Maximin Principle Serve as a Basis for Morality? A Critique of John Rawls's Theory.- V. Nonlinear Social Welfare Functions: Do Welfare Economists Have a Special Exemption from Bayesian Rationality?.- B / Rational-Choice and Game Theoretical Models of Social Behavior.- VI. Advances in Understanding Rational Behavior.- VII. Rational-Choice Models of Political Behavior vs. Functionalist and Conformist Theories.- VIII. Game Theory and the Analysis of International Conflicts.- IX. Measurement of Social Power, Opportunity Costs, and the Theory of Two-Person Bargaining Games.- X. Measurement of Social Power in n-Person Reciprocal Power Situations.- XI. A Bargaining Model for Social Status in Informal Groups and Formal Organizations.- C / Scientific Explanation.- XII. Explanation and Comparative Dynamics in Social Science.- XIII. Popper's Improbability Criterion for the Choice of Scientific Hypotheses.