Agreeing to Disagree Politically

Taylor, Brad R. ORCID: and Bosworth, William (2018) Agreeing to Disagree Politically. In: Australasian Public Choice Conference (2018), 10-11 Dec 2018, Melbourne, Australia.


Robert Aumann's agreement theorem and subsequent work shows that people who are rational in a certain Bayesian sense cannot agree to disagree on matters of fact, as long as there is common knowledge of this common rationality. This result hinges on a type of epistemic impartiality: a rational person will not give extra weight to a piece of evidence simply because they themselves discovered it rather than someone else. Of course, 'Good Bayesians' who agree on matters of fact can nevertheless disagree due to differences of preference and value. We question the possibility of reasonable political disagreement by adding a 'public reason' constraint derived from the political liberalism of John Rawls and interpreted more precisely in light of work by John Harsanyi. On our reading, a 'Good Liberal' must not give extra weight in public deliberations to their own preferences or values simply because they are their own. This political impartiality mirrors the epistemic impartiality of Aumann's theorem and we argue that disagreement on policy is impossible in a world of 'Good Liberal Bayesians', assuming common knowledge of both Bayesian rationality and Liberal reasonableness.

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Item Type: Conference or Workshop Item (Commonwealth Reporting Category E) (Paper)
Refereed: Yes
Item Status: Live Archive
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Faculty/School / Institute/Centre: Historic - Faculty of Business, Education, Law and Arts - School of Commerce (1 Jul 2013 - 17 Jan 2021)
Faculty/School / Institute/Centre: Historic - Faculty of Business, Education, Law and Arts - School of Commerce (1 Jul 2013 - 17 Jan 2021)
Date Deposited: 05 Feb 2020 05:05
Last Modified: 28 Nov 2022 00:01
Uncontrolled Keywords: Agreement theorem; Bayesian rationality
Fields of Research (2008): 14 Economics > 1402 Applied Economics > 140213 Public Economics-Public Choice
22 Philosophy and Religious Studies > 2203 Philosophy > 220319 Social Philosophy
16 Studies in Human Society > 1606 Political Science > 160609 Political Theory and Political Philosophy
Fields of Research (2020): 38 ECONOMICS > 3801 Applied economics > 380113 Public economics - public choice
50 PHILOSOPHY AND RELIGIOUS STUDIES > 5003 Philosophy > 500321 Social and political philosophy
44 HUMAN SOCIETY > 4408 Political science > 440811 Political theory and political philosophy
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970122 Expanding Knowledge in Philosophy and Religious Studies
E Expanding Knowledge > 97 Expanding Knowledge > 970114 Expanding Knowledge in Economics
C Society > 94 Law, Politics and Community Services > 9402 Government and Politics > 940201 Civics and Citizenship
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