Group Communication and the Transformation of Judgments: An Impossibility Result

While a large social-choice-theoretic literature discusses the aggregation of individual judgments into collective ones, there is much less formal work on the transformation of judgments in group communication. I develop a model of judgment transformation and prove a baseline impossibility theorem: Any judgment transformation function satisfying some initially plausible conditions is the identity function, under which no opinion change occurs. I identify escape routes from this impossibility and argue that the kind of group communication envisaged by deliberative democats must be "holistic": It must focus on webs of connected propositions, not on one proposition at a time, which echoes the Duhem-Quine "holism thesis" on scientific theory testing. My approach provides a map of the logical space in which different possible group communication processes are located.

[1]  D. Black.  On the Rationale of Group Decision-making , 1948, Journal of Political Economy.

[2]  W. Quine.  Main trends in recent philosophy: two dogmas of empiricism. , 1951 .

[3]  L. A. Goodman,et al.  Social Choice and Individual Values , 1951 .

[4]  W. Quine.  The two dogmas of empiricism , 1951 .

[5]  Amartya Sen,et al.  A Possibility Theorem on Majority Decisions , 1966 .

[6]  M. Degroot.  Reaching a Consensus , 1974 .

[7]  Robert B. Wilson.  On the theory of aggregation , 1975 .

[8]  Peter Gärdenfors,et al.  On the logic of theory change: Partial meet contraction and revision functions , 1985, Journal of Symbolic Logic.

[9]  W. Riker.  The art of political manipulation , 1987 .

[10]  Lawrence G. Sager,et al.  Unpacking the Court , 1986 .

[11]  Jon Elster,et al.  The market and the forum , 1986 .

[12]  P. Fishburn,et al.  Algebraic aggregation theory , 1986 .

[13]  Philip Pettit,et al.  The good polity : normative analysis of the state , 1991 .

[14]  John S. Dryzek,et al.  Discursive Democracy: Politics, Policy, and Political Science , 1992 .

[15]  David Miller,et al.  Deliberative Democracy and Social Choice , 1992 .

[16]  Lawrence G. Sager,et al.  The One and the Many: Adjudication in Collegial Courts , 1993 .

[17]  Cass R. Sunstein,et al.  Political Conflict and Legal Agreement , 1994 .

[18]  J. Knight,et al.  Aggregation and Deliberation: On the Possibility of Democratic Legitimacy , 1994 .

[19]  Alain Boyer.  Democracy and Disagreement , 1995 .

[20]  Dennis F. Thompson,et al.  Democracy and Disagreement , 1996 .

[21]  J. Bohman,et al.  Deliberative Democracy: Essays on Reason and Politics , 1997 .

[22]  Ariel Rubinstein,et al.  On the Question "Who is a J?": A Social Choice Approach , 1998 .

[23]  Dennis Davis,et al.  Democracy and deliberation , 1999 .

[24]  C. Sunstein.  The Law of Group Polarization , 1999, How Change Happens.

[25]  J. Dryzek.  Deliberative Democracy And Beyond , 2000 .

[26]  P. Pettit.  Deliberative Democracy and the Discursive Dilemma , 2001 .

[27]  C. List,et al.  Aggregating Sets of Judgments: An Impossibility Result , 2002, Economics and Philosophy.

[28]  B. Chapman,et al.  Rational Aggregation , 2002 .

[29]  Jürgen Habermas,et al.  Social Choice Theory and Deliberative Democracy : A Reconciliation , 2002 .

[30]  Christian List,et al.  Two Concepts of Agreement , 2002 .

[31]  James S. Fishkin,et al.  Considered Opinions: Deliberative Polling in Britain , 2002 .

[32]  Sébastien Konieczny,et al.  Merging Information Under Constraints: A Logical Framework , 2002, J. Log. Comput..

[33]  Oliver Schulte,et al.  Minimal belief change, Pareto-optimality and logical consequence , 2002 .

[34]  Klaus Nehring,et al.  Arrow’s theorem as a corollary , 2003 .

[35]  Christian List,et al.  A possibility theorem on aggregation over multiple interconnected propositions , 2003, Math. Soc. Sci..

[36]  Christian List,et al.  A Model of Path-Dependence in Decisions over Multiple Propositions , 2002, American Political Science Review.

[37]  Sébastien Konieczny,et al.  Belief base merging as a game , 2004, J. Appl. Non Class. Logics.

[38]  Christian List,et al.  Aggregating Sets of Judgments: Two Impossibility Results Compared1 , 2004, Synthese.

[39]  Marion Kee,et al.  Analysis , 2004, Machine Translation.

[40]  J. Rawls,et al.  A Theory of Justice , 1971, Princeton Readings in Political Thought.

[41]  Joshua Cohen,et al.  DELIBERATION AND DEMOCRATIC LEGITIMACY , 2005, Philosophy, Politics, Democracy.

[42]  Sébastien Konieczny,et al.  Conciliation and Consensus in Iterated Belief Merging , 2005, ECSQARU.

[43]  F. Dietrich,et al.  Judgment Aggregation By Quota Rules , 2007 .

[44]  T. Feddersen,et al.  Deliberation, Preference Uncertainty, and Voting Rules , 2006, American Political Science Review.

[45]  Marc Pauly,et al.  Logical Constraints on Judgement Aggregation , 2006, J. Philos. Log..

[46]  G. Mackie.  Does democratic deliberation change minds? , 2006 .

[47]  C. List.  The Discursive Dilemma and Public Reason* , 2006, Ethics.

[48]  Luc Bovens,et al.  Democratic Answers to Complex Questions – An Epistemic Perspective , 2006, Synthese.

[49]  P. Gärdenfors.  A REPRESENTATION THEOREM FOR VOTING WITH LOGICAL CONSEQUENCES , 2006, Economics and Philosophy.

[50]  Franz Dietrich,et al.  Judgment aggregation: (im)possibility theorems , 2006, J. Econ. Theory.

[51]  R. Calvert.  Deliberation as Coordination through Cheap Talk , 2006 .

[52]  Gabriella Pigozzi,et al.  Belief merging and the discursive dilemma: an argument-based account to paradoxes of judgment aggregation , 2006, Synthese.

[53]  P. Pettit.  When to defer to majority testimony - and when not , 2006 .

[54]  Franz Dietrich,et al.  A generalised model of judgment aggregation , 2007, Soc. Choice Welf..

[55]  Klaus Nehring,et al.  The impossibility of a Paretian rational: A Bayesian perspective , 2007 .

[56]  Christian List,et al.  Arrow’s theorem in judgment aggregation , 2005, Soc. Choice Welf..

[57]  Martin van Hees,et al.  The limits of epistemic democracy , 2007, Soc. Choice Welf..

[58]  Christian List,et al.  STRATEGY-PROOF JUDGMENT AGGREGATION* , 2005, Economics and Philosophy.

[59]  Richard Bradley,et al.  Reaching a consensus , 2007, Soc. Choice Welf..

[60]  Catherine Hafer,et al.  Deliberation as Self-Discovery and Institutions for Political Speech , 2007 .

[61]  Christian List,et al.  Judgment aggregation without full rationality , 2008, Soc. Choice Welf..

[62]  Klaus Nehring,et al.  Consistent judgement aggregation: the truth-functional case , 2008, Soc. Choice Welf..

[63]  Adam Meirowitz,et al.  Game theory, information, and deliberative democracy , 2009 .

[64]  Ron Holzman,et al.  Aggregation of binary evaluations with abstentions , 2010, J. Econ. Theory.

[65]  Klaus Nehring,et al.  Abstract Arrowian aggregation , 2010, J. Econ. Theory.

[66]  Ron Holzman,et al.  Aggregation of binary evaluations , 2010, J. Econ. Theory.

[67]  Christian List,et al.  Deliberation, Single-Peakedness, and the Possibility of Meaningful Democracy: Evidence from Deliberative Polls , 2006, The Journal of Politics.

[68]  G. Boniolo.  Deliberation and democracy , 2012 .