Theory and Decision

, Volume 36, Issue 2, pp 131–162 | Cite as

Opinion leaders, independence, and Condorcet's Jury Theorem

  • David M. Estlund


Condorcet's Jury Theorem shows that on a dichotomous choice, individuals who all have the same competence above 0.5, can make collective decisions under majority rule with a competence that approaches 1 as either the size of the group or the individual competence goes up. The theorem assumes that the probability of each voter's being correct is independent of the probability of any other voter being correct. Contrary to several authors, the presence of mutual or common influences such as opinion leaders does not easily rule independence either in or out. Indeed, and this ought to be surprising,under certain conditions deference to opinion leaders can improve individual competence without violating independence, and so can raise group competence as well.


Condorcet Jury Theorem voting democracy independence judgments 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Black, Duncan: 1958,The Theory of Committees and Elections, Cambridge University Press.Google Scholar
  2. Condorcet, Marquis de: 1785,Essai sur l'application de l'analyse à la probabilité des decisions rendues à la pluralité des voix, Paris, 1785.Google Scholar
  3. Estlund, D., Waldron, J., Grofman, B., and Feld, S.: 1989, ‘Democratic theory and the public interest: Condorcet and Rousseau revisited’ (Controversy including a piece by D. Estlund, one by J. Waldron, and a reply by B. Grofman and S. Feld),American Political Science Review 83(4).Google Scholar
  4. Estlund, D.: 1993, ‘Making truth safe for democracy’, in: D. Copp, J. Hampton, and J. Roemer (Eds.),The Idea of Democracy, Cambridge University Press.Google Scholar
  5. Grofman, B. and Feld, S.: 1988, ‘Rousseau's general will: a Condorcetian perspective’,American Political Science Review 82(2).Google Scholar
  6. Grofman, B., Owen, G., and Feld, S.: 1983, ‘Thirteen theorems in search of the truth’,Theory and Decision 15.Google Scholar
  7. Lipshutz, Seymour: 1965,Theory and Problems of Probability, Schaum's Outline Series, McGraw-Hill.Google Scholar
  8. Owen, G., Grofman, B., and Feld, S.: 1989, ‘Proving a distribution-free generalization of the Condorcet jury theorem’,Mathematical Social Sciences 17, 1–16.Google Scholar
  9. Rawls, J.: 1971,A Theory of Justice, Harvard University Press, Cambridge, MA.Google Scholar
  10. Shapley, L. and Grofman, B.: 1984, ‘Optimal group judgmental accuracy in the presence of interdependencies’,Public Choice 43.Google Scholar

Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • David M. Estlund
    • 1
  1. 1.Dept. of PhilosophyBrown UniversityProvidenceUSA

Personalised recommendations