scholarly journals Information Aggregation, Rationality, and the Condorcet Jury Theorem

1996 ◽  
Vol 90 (1) ◽  
pp. 34-45 ◽  
Author(s):  
David Austen-Smith ◽  
Jeffrey S. Banks
Keyword(s):  
Decision Making ◽  
Nash Equilibrium ◽  
Information Aggregation ◽  
Collective Decision Making ◽  
Single Individual ◽  
Condorcet Jury Theorem ◽  
Jury Theorem ◽  
Sincere Voting ◽  
Two Alternatives ◽  
Better Than

The Condorcet Jury Theorem states that majorities are more likely than any single individual to select the “better” of two alternatives when there exists uncertainty about which of the two alternatives is in fact preferred. Most extant proofs of this theorem implicitly make the behavioral assumption that individuals vote “sincerely” in the collective decision making, a seemingly innocuous assumption, given that individuals are taken to possess a common preference for selecting the better alternative. However, in the model analyzed here we find that sincere behavior by all individuals is not rational even when individuals have such a common preference. In particular, sincere voting does not constitute a Nash equilibrium. A satisfactory rational choice foundation for the claim that majorities invariably “do better” than individuals, therefore, has yet to be derived.

scholarly journals REPRESENTATION IN MODELS OF EPISTEMIC DEMOCRACY

Episteme ◽  
2018 ◽  
Vol 17 (4) ◽  
pp. 498-518
Author(s):  
Patrick Grim ◽  
Aaron Bramson ◽  
Daniel J. Singer ◽  
William J. Berger ◽  
Jiin Jung ◽  
...  
Keyword(s):  
Decision Making ◽  
Information Aggregation ◽  
Epistemic Democracy ◽  
Condorcet Jury Theorem ◽  
Analytic Work ◽  
Direct Participation ◽  
Epistemic Virtues ◽  
Collaborative Search ◽  
Jury Theorem ◽  
Group Search

ABSTRACTEpistemic justifications for democracy have been offered in terms of two different forms of information aggregation and decision-making. The Condorcet Jury Theorem is appealed to as a justification in terms of votes, and the Hong–Page ‘diversity trumps ability’ result is appealed to as a justification in terms of deliberation in the form of collaborative search. Both results, however, are models of full and direct participation across a population. In this paper, we contrast how these results hold up within the familiar structure of a representative hierarchy. We first consider extant analytic work that shows that representation inevitably weakens the voting results of the Condorcet Jury Theorem. We then go on to show that collaborative search, as modeled by Hong and Page, holds its own within hierarchical representation. In a variation on the dynamics of group search, representation even shows a slight edge over direct participation. This contrast illustrates how models of information aggregation vary when put into a representative structure. While some of the epistemic merits of democracy are lost when voting is done hierarchically, modeling results show that representation can preserve and even slightly amplify the epistemic virtues of collaborative search.

scholarly journals Consequences of the Condorcet Jury Theorem for Beneficial Information Aggregation by Rational Agents

1998 ◽  
Vol 92 (2) ◽  
pp. 413-418 ◽  
Author(s):  
Andrew McLennan
Keyword(s):  
Nash Equilibria ◽  
Information Aggregation ◽  
Common Interest ◽  
Condorcet Jury Theorem ◽  
Rational Agents ◽  
Incorrect Decision ◽  
Jury Theorem ◽  
The One ◽  
Sincere Voting

“Naïve” Condorcet Jury Theorems automatically have “sophisticated” versions as corollaries. A Condorcet Jury Theorem is a result, pertaining to an election in which the agents have common preferences but diverse information, asserting that the outcome is better, on average, than the one that would be chosen by any particular individual. Sometimes there is the additional assertion that, as the population grows, the probability of an incorrect decision goes to zero. As a consequence of simple properties of common interest games, whenever “sincere” voting leads to the conclusions of the theorem, there are Nash equilibria with these properties. In symmetric environments the equilibria may be taken to be symmetric.

Making the most of individual differences in joint decisions

2018 ◽  
Author(s):  
Bahador Bahrami
Keyword(s):  
Decision Making ◽  
Direct Evidence ◽  
Cross Cultural ◽  
Collective Decision Making ◽  
Wisdom Of Crowds ◽  
Trade Off ◽  
Adaptive Value ◽  
Joint Decisions ◽  
Cultural Data ◽  
Better Than

Evidence for and against the idea that “two heads are better than one” is abundant. This chapter considers the contextual conditions and social norms that predict madness or wisdom of crowds to identify the adaptive value of collective decision-making beyond increased accuracy. Similarity of competence among members of a collective impacts collective accuracy, but interacting individuals often seem to operate under the assumption that they are equally competent even when direct evidence suggest the opposite and dyadic performance suffers. Cross-cultural data from Iran, China, and Denmark support this assumption of similarity (i.e., equality bias) as a sensible heuristic that works most of the time and simplifies social interaction. Crowds often trade off accuracy for other collective benefits such as diffusion of responsibility and reduction of regret. Consequently, two heads are sometimes better than one, but no-one holds the collective accountable, not even for the most disastrous of outcomes.

scholarly journals Liquid Democracy: An Algorithmic Perspective

2021 ◽  
Vol 70 ◽  
pp. 1223-1252
Author(s):  
Anson Kahng ◽  
Simon Mackenzie ◽  
Ariel Procaccia
Keyword(s):  
Decision Making ◽  
Collective Decision ◽  
Collective Decision Making ◽  
Main Question ◽  
Correct Decision ◽  
Majority Opinion ◽  
Local Neighborhood ◽  
Liquid Democracy ◽  
Non Local ◽  
Two Alternatives

We study liquid democracy, a collective decision making paradigm that allows voters to transitively delegate their votes, through an algorithmic lens. In our model, there are two alternatives, one correct and one incorrect, and we are interested in the probability that the majority opinion is correct. Our main question is whether there exist delegation mechanisms that are guaranteed to outperform direct voting, in the sense of being always at least as likely, and sometimes more likely, to make a correct decision. Even though we assume that voters can only delegate their votes to better-informed voters, we show that local delegation mechanisms, which only take the local neighborhood of each voter as input (and, arguably, capture the spirit of liquid democracy), cannot provide the foregoing guarantee. By contrast, we design a non-local delegation mechanism that does provably outperform direct voting under mild assumptions about voters.

Truth-tracing versus truth-tracking: Lafont, Landemore and epistemic democracy

2020 ◽  
pp. 019145372097471
Author(s):  
Peter Niesen
Keyword(s):  
Decision Making ◽  
Public Reason ◽  
Epistemic Democracy ◽  
Condorcet Jury Theorem ◽  
The Public ◽  
Plausible Account ◽  
Jury Theorem ◽  
Theory Of Democracy

Cognitivist theories of democratic decision-making come in two flavours, which I label transparently and intransparently epistemic. Lafont’s deliberative theory of democracy has strengths in accounting for the transparently truth-tracing power of justification but lacks a plausible account of the intransparently truth-tracking power of aggregative approaches highlighted by, among others, Hélène Landemore, such as the Condorcet Jury Theorem or the Diversity Trumps Ability Theorem. I suggest opting for an approach that includes semi-transparently epistemic mechanisms, that is, truth-tracking mechanisms, the workings of which can be explained, passing the public reason test, to all citizens.

scholarly journals A Condorcet Jury Theorem for Large Poisson Elections with Multiple Alternatives

Games ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 2
Author(s):  
Johanna M. M. Goertz
Keyword(s):  
The State ◽  
Previous Literature ◽  
Plurality Rule ◽  
Condorcet Jury Theorem ◽  
Correct Alternative ◽  
State Of Nature ◽  
Voting Game ◽  
Common Interests ◽  
Jury Theorem ◽  
Two Alternatives

Herein, we prove a Condorcet jury theorem (CJT) for large elections with multiple alternatives. Voters have common interests that depend on an unknown state of nature. Each voter receives an imprecise private signal about the state of nature and then submits one vote (simple plurality rule). We also assume that this is a Poisson voting game with population uncertainty. The question is whether the simple plurality rule aggregates information efficiently so that the correct alternative is elected with probability tending to one when the number of voters tends to infinity. The previous literature shows that the CJT holds for large elections with two alternatives, but there is also an example of a large election with three alternatives that has an inefficient equilibrium. We show that there always exists an efficient equilibrium, independent of the number of alternatives. Under certain circumstances (informative types), it is unique in elections with two alternatives. The existence of inefficient equilibria in elections with more than two alternatives is generic.

scholarly journals EPISTEMIC DEMOCRACY WITH DEFENSIBLE PREMISES

2013 ◽  
Vol 29 (1) ◽  
pp. 87-120 ◽  
Author(s):  
Franz Dietrich ◽  
Kai Spiekermann
Keyword(s):  
Small Groups ◽  
Wisdom Of Crowds ◽  
Contemporary Theory ◽  
Epistemic Democracy ◽  
Current Form ◽  
Condorcet Jury Theorem ◽  
Jury Theorem ◽  
Misleading Conclusion ◽  
Better Than ◽  
The Wisdom Of Crowds

The contemporary theory of epistemic democracy often draws on the Condorcet Jury Theorem to formally justify the ‘wisdom of crowds’. But this theorem is inapplicable in its current form, since one of its premises – voter independence – is notoriously violated. This premise carries responsibility for the theorem's misleading conclusion that ‘large crowds are infallible’. We prove a more useful jury theorem: under defensible premises, ‘large crowds are fallible but better than small groups’. This theorem rehabilitates the importance of deliberation and education, which appear inessential in the classical jury framework. Our theorem is related to Ladha's (1993) seminal jury theorem for interchangeable (‘indistinguishable’) voters based on de Finetti's Theorem. We also prove a more general and simpler such jury theorem.

scholarly journals Epistemic aspects of representative government

2011 ◽  
Vol 4 (3) ◽  
pp. 303-325 ◽  
Author(s):  
Robert E. Goodin ◽  
Kai Spiekermann
Keyword(s):  
Small Group ◽  
Representative Democracy ◽  
Electoral College ◽  
Representative Government ◽  
Condorcet Jury Theorem ◽  
The Federalist ◽  
General Mass ◽  
Jury Theorem ◽  
Better Than

The Federalist, justifying the Electoral College to elect the president, claimed that a small group of more informed individuals would make a better decision than the general mass. But the Condorcet Jury Theorem tells us that the more independent, better-than-random voters there are, the more likely it will be that the majority among them will be correct. The question thus arises as to how much better, on average, members of the smaller group would have to be to compensate for the epistemic costs of making decisions on the basis of that many fewer votes. This question is explored in the contexts of referendum democracy, delegate-style representative democracy, and trustee-style representative democracy.

scholarly journals EPISTEMIC SOLIDARITY AS A POLITICAL STRATEGY

Episteme ◽  
2015 ◽  
Vol 12 (4) ◽  
pp. 439-457 ◽  
Author(s):  
Robert E. Goodin ◽  
Kai Spiekermann
Keyword(s):  
Collective Action ◽  
False Consciousness ◽  
Political Strategy ◽  
Condorcet Jury Theorem ◽  
Jury Theorem ◽  
The Masses ◽  
Better Than

ABSTRACTSolidarity is supposed to facilitate collective action. We argue that it can also help overcome false consciousness. Groups practice ‘epistemic solidarity’ if they pool information about what is in their true interest and how to vote accordingly. The more numerous ‘Masses’ can in this way overcome the ‘Elites,’ but only if they are minimally confident with whom they share the same interests and only if they are (perhaps only just) better-than-random in voting for the alternative that promotes their interests. Being more cohesive and more competent than the Masses, the Elites can employ the same strategy perhaps all the more effectively. But so long as the Masses practice epistemic solidarity they will almost always win, whether or not the Elites do. By enriching the traditional framework of the Condorcet Jury Theorem with group-specific standards of correctness, we investigate how groups can organize to support the alternatives truly in their interests.

Sign in / Sign up

Export Citation Format

Share Document