Maurice Salles

The utilitarian economist and Nobel Laureate John Harsanyi and the liberal egalitarian philosopher John Rawls were two of the most eminent scholars writing on problems of social justice in the last century. This volume pays tribute to Harsanyi and Rawls by investigating themes that figure prominently in their work. In some cases, the contributors explore issues considered by Harsanyi and Rawls in more depth and from novel perspectives. In others, the contributors use the work of Harsanyi and Rawls as points of departure for pursuing the construction of theories for the evaluation of social justice. The introductory essay by the editors provides background information on the relevant economics, game theory, philosophy, and social choice theory, as well as readers' guides to the individual contributions, to make this volume widely accessible to scholars in a wide range of disciplines.

This paper describes an unknown episode in the development of the theory of social choice. In the Summer 1949, while at RAND, Quine worked on Arrow’s (im)possibility theorem. This work was eventually published as a paper on (applied) set theory totally disconnected from social choice. The working paper directly linked to Arrow’s work was never published. I alluded to this (then unwritten) paper in a number of presentations I made on ‘Logic and Social Choice’ in Turku, Bucharest, Boston, Strasbourg and Munich, between October 2013 and January 2015. It was eventually first presented during a conference at Queen Mary, University of London, 19–20 June 2015, on ‘Social Welfare, Justice and Distribution: Celebrating John Roemer’s Contributions to Economics, Political Philosophy and Political Science’, organized by Roberto Veneziani and Juan Moreno-Ternero. I am grateful to the participants for interesting reactions and comments, in particular Richard Arneson, Jon Elster, Marc Fleurbaey, Klaus Nehring and Gil Skillman. Jon Elster contacted Dagfinn Føllesdal, a well-known philosopher and a pre-eminent Quine scholar, who kindly responded to some queries. A more developed version was presented in Aix-en-Provence during the International Conference on Economic Philosophy and in Lund during the meeting of the Society for Social Choice and Welfare in June 2016. Comments of participants to these two events revealed to be very helpful, among which comments by Gilles Campagnolo, Christian List and John Weymark. While in Lund, I also greatly benefitted from conversations with Adrian Miroiu. Finally, I am very grateful to an Associate Editor of this journal for excellent suggestions and for detecting some very annoying slips.

Social choice and welfare economics are subjects at the frontier of many disciplines. Even if economics played the major role in their development, sociology, psychology and, principally, political science, mathematics and philosophy have been central for the manifold inventiveness of the employed methods and for the diversity of the studied topics. This phenomenon can be compared with game theory, a subject which has, of course, many connections with social choice and welfare. This fact is reflected by the disciplinary origins of the contributors to the subject and, as an anecdote, by the disciplinary origins of the board of editors of this journal. Philosophers are expected to contribute mainly to the study of social justice and related ethical questions. But there is a tradition among logicians for studying voting theory. A famous example is C. L. Dodgson (Lewis Carroll), even though the complete works of Dodgson on voting occupy only a few pages. A major recent example is Michael Dummett. Michael Dummett is famous among social choice theorists for his joint paper with Robin Farquharson published in Econometrica in 1961. Later he wrote two important books on voting (Dummett (1984, 1997); for an overview see Salles (2006)). But it must be outlined that Michael Dummett is also, and above all, one of the greatest contemporary philosophers whose work on the German logician Frege, on intuitionism, realism, anti-realism, justificationism has been central for the development of analytical philosophy in the second part of the last century and in this century (an example is the Symposium in a recent issue of Mind (see Peacocke (2005) and Dummett (2005)). Sir Michael Dummett is Wykeham Professor of Logic emeritus at Oxford University. His interview was conducted at New College, Oxford in September 2004.

This paper is a survey of how economists and philosophers approach the issue of comparisons. More precisely, it is about what formal representation is appropriate whenever our ability to compare things breaks down. We restrict our attention to failures that arise with ordinal comparisons. We consider a number of formal approaches to this problem including one based on the idea of parity. We also consider the claim that the failure to compare things is a consequence of vagueness. We contrast two theories of vagueness; fuzzy set theory and supervaluation theory. Some applications of these theories are described.