2 November 2009
Social Choice Colloquim at Tilburg University
Posted by Rasmus Rendsvig under: Activities; Courses, seminars and special lectures; Decision Theory; Dynamic Epistemic Logic; Game Theory; Social Choice Theory .
| Friday, December 4, 2009 |
Michel Regenwetter and Olivier Roy will be giving talks at the Social Choice Colloquim at Tilburg University on the 4th of December, 2009. Titles and abstracts of the talks can be found below.
10:45-11:45 Michel Regenwetter (University of Illinois at Champaign), Behavioral Social Choice I: The Condorcet paradox.
This talk introduces behavioral social choice as a social choice parallel to important developments in other decision sciences, such as behavioral decision theory, behavioral economics, behavioral finance and behavioral game theory. Behavioral paradigms compare how rational actors should make certain types of decisions with how real decision makers behave empirically. Important theoretical predictions in social choice theory change dramatically under even minute violations of standard assumptions. Empirical data violate some of those critical assumptions. The nature of preference distributions in electorates is ultimately an empirical question, which social choice theory has often neglected. This talk will place a strong emphasis on discussing the lack of empirical evidence for the famous Condorcet paradox of majority cycles.
12:00-13:00, Olivier Roy (University of Groningen), Higher-order information and belief dynamics: the perspective of dynamic-epistemic logic on agreement results.
In this talk I will revisit R. Aumann’s “Agreement Theorem” (1976) and two of its subsequent generalizations, by J. Geanakoplos and H.M. Polemarchakis (1982) and M. Bacharach (1985), from the perspective of dynamic-epistemic logic. These results are usually taken to undermine the importance of private information in interactive situations, as well as to highlight the (too) strong implications of notions such as common knowledge and common prior belief. I will argue that dynamic-epistemic logic allows for a more positive reading of Agreement Theorems, namely that they show the importance of higher-order information (information about information) in interactive situations and that they stress the difference between conditioning and “genuine” belief dynamics.
13:00-13:30 Lunch: tea, coffee and sandwiches will be served.
13:30-14:30, Michel Regenwetter (University of Illinois at Champaign), Behavioral Social Choice II: Consensus among consensus methods.
For centuries, the mathematical aggregation of preferences by groups, organizations, or society itself has received keen interdisciplinary attention. Extensive theoretical work in economics and political science throughout the second half of the 20th century has highlighted the idea that competing notions of rational social choice intrinsically contradict each other. This has led some researchers to consider coherent democratic decision making to be a mathematical impossibility. This presentation reviews recent empirical work in psychology that qualifies this view, and poses a series of open questions. Some classical work sometimes makes assumptions about voter preferences that are descriptively invalid. Do such technical assumptions lead the theory astray? How can empirical work inform the formulation of meaningful theoretical primitives? Classical ‘‘impossibility results’’ leverage the fact that certain desirable mathematical properties logically cannot hold in all conceivable electorates. Do these properties nonetheless hold true in empirical distributions of preferences?
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