Kenneth J. Arrow's pathbreaking "impossibility theorem" was a watershed innovation in the history of welfare economics, voting theory, and collective choice, demonstrating that there is no voting rule that satisfies the four desirable axioms of decisiveness, consensus, nondictatorship, and independence. In this book Eric Maskin and Amartya Sen explore the implications of Arrow's theorem. Sen considers its ongoing utility, exploring the theorem's value and limitations in relation to recent research on social reasoning, and Maskin discusses how to design a voting rule that gets us closer to the ideal―given the impossibility of achieving the ideal. The volume also contains a contextual introduction by social choice scholar Prasanta K. Pattanaik and commentaries from Joseph E. Stiglitz and Kenneth J. Arrow himself, as well as essays by Maskin, Dasgupta, and Sen outlining the mathematical proof and framework behind their assertions. Without hyperbole, no postwar intellectual of the first rank has done more good for more people―above all, many of the world's poorest―than Amartya Sen. -- Boyd Tonkin ― The Independent What is Arrow's impossibility theorem? Why is it true? What are its implications for democratic decision making? Is its nihilism justified? These are the kinds of questions addressed in Maskin and Sen's masterful Arrow lectures. These lectures and the accompanying essays provide an accessible introduction to Kenneth J. Arrow's theorem for the neophyte and much food for thought for the cognoscente. -- John A. Weymark, Vanderbilt University How vital it is to understand the ideas behind Kenneth J. Arrow's impossibility theorem if we want to design reasonably fair ways of coming to consensus decisions that take equitable account of individual preferences. This book is a marvelous introduction to the theorem, a keystone in the theory of social choice. We are treated to a discussion of that theory―its origin, background, and the challenges it points to―by some of its great architects. -- Barry Mazur, Harvard University, author of Imagining Numbers The pioneers of social choice theory give us lively, enjoyable, and stimulating lectures and exchanges of ideas. Their views, more than sixty years after the publication of Kenneth J. Arrow's theorem, are of paramount interest to anyone aware of the difficulties of collective decisions. -- Marc Fleurbaey, Princeton University Professor Dasgupta is the Frank Ramsey Professor of Economics at the University of Cambridge. He is also the Andrew D. White Professor-at-Large at Cornell University and is currently President of the European Association of Environmental and Resource Economists. His books include Economics: A Very Short Introduction (OUP, 2017), Human Well-Being and the Natural Environment (OUP, 2004) and An Inquiry into Well-Being and Destitution (OUP, 1993).