Third-party punishment as a costly signal of trustworthiness

Published online:


Third-party punishment (TPP)1,2,3,4,5,6,7, in which unaffected observers punish selfishness, promotes cooperation by deterring defection. But why should individuals choose to bear the costs of punishing? We present a game theoretic model of TPP as a costly signal8,9,10 of trustworthiness. Our model is based on individual differences in the costs and/or benefits of being trustworthy. We argue that individuals for whom trustworthiness is payoff-maximizing will find TPP to be less net costly (for example, because mechanisms11 that incentivize some individuals to be trustworthy also create benefits for deterring selfishness via TPP). We show that because of this relationship, it can be advantageous for individuals to punish selfishness in order to signal that they are not selfish themselves. We then empirically validate our model using economic game experiments. We show that TPP is indeed a signal of trustworthiness: third-party punishers are trusted more, and actually behave in a more trustworthy way, than non-punishers. Furthermore, as predicted by our model, introducing a more informative signal—the opportunity to help directly—attenuates these signalling effects. When potential punishers have the chance to help, they are less likely to punish, and punishment is perceived as, and actually is, a weaker signal of trustworthiness. Costly helping, in contrast, is a strong and highly used signal even when TPP is also possible. Together, our model and experiments provide a formal reputational account of TPP, and demonstrate how the costs of punishing may be recouped by the long-run benefits of signalling one’s trustworthiness.

  • Subscribe to Nature for full access:



Additional access options:

Already a subscriber?  Log in  now or  Register  for online access.


  1. 1.

    & Third-party punishment and social norms. Evol. Hum. Behav. 25, 63–87 (2004)

  2. 2.

    , & The impact of group membership on cooperation and norm enforcement: evidence using random assignment to real social groups. Am. Econ. Rev. 96, 212–216 (2006)

  3. 3.

    , & The effects of endowment size and strategy method on third party punishment. Exp. Econ. (2015)

  4. 4.

    , & Audience effects on moralistic punishment. Evol. Hum. Behav. 28, 75–84 (2007)

  5. 5.

    & Norm enforcement in the city: a natural field experiment. Eur. Econ. Rev. 56, 1773–1785 (2012)

  6. 6.

    & Punishment sustains large-scale cooperation in prestate warfare. Proc. Natl Acad. Sci. USA 108, 11375–11380 (2011)

  7. 7.

    , , & Fairness violations elicit greater punishment on behalf of another than for oneself. Nature Commun. 5, 5306 (2014)

  8. 8.

    Mate selection—a selection for a handicap. J. Theor. Biol. 53, 205–214 (1975)

  9. 9.

    , & Costly signaling and cooperation. J. Theor. Biol. 213, 103–119 (2001)

  10. 10.

    Competitive altruism: from reciprocity to the handicap principle. Proc. Biol. Sci. 265, 427–431 (1998)

  11. 11.

    & Human cooperation. Trends Cogn. Sci. 17, 413–425 (2013)

  12. 12.

    Reciprocity: weak or strong? What punishment experiments do (and do not) demonstrate. Behav. Brain Sci. 35, 1–15 (2012)

  13. 13.

    et al. Costly punishment across human societies. Science 312, 1767–1770 (2006)

  14. 14.

    & Evolution of indirect reciprocity. Nature 437, 1291–1298 (2005)

  15. 15.

    & The reputation of punishers. Trends Ecol. Evol. 30, 98–103 (2015)

  16. 16.

    Reputational benefits for altruistic punishment. Evol. Hum. Behav. 27, 325–344 (2006)

  17. 17.

    & in The Genetic and Cultural Evolution of Cooperation (ed. ) (MIT Press, 2003)

  18. 18.

    & Indirect reciprocity can stabilize cooperation without the second-order free rider problem. Nature 108, 432–502 (2014)

  19. 19.

    , & A mutualistic approach to morality: the evolution of fairness by partner choice. Behav. Brain Sci. 36, 59–78 (2013)

  20. 20.

    , & Coordinated punishment of defectors sustains cooperation and can proliferate when rare. Science 328, 617–620 (2010)

  21. 21.

    Robustness against indirect invasions. Games Econ. Behav. 74, 382–393 (2012)

  22. 22.

    The price you pay: cost-dependent reputation effects of altruistic punishment. Evol. Hum. Behav. 29, 242–248 (2008)

  23. 23.

    , & Humans display a ‘cooperative phenotype’ that is domain general and temporally stable. Nature Commun. 5, 4939 (2014)

  24. 24.

    Punishers may be chosen as providers but not as recipients. Lett. Evol. Behav. Sci. 1, 6–9 (2010)

  25. 25.

    & Intuition, deliberation, and the evolution of cooperation. Proc. Natl Acad. Sci. USA 113, 936–941 (2016)

  26. 26.

    & Habits of virtue: creating norms of cooperation and defection in the laboratory. Management Science (2015)

  27. 27.

    & Third-party punishers are rewarded, but third-party helpers even more so. Evolution 69, 993–1003 (2015)

Download references


We gratefully acknowledge the John Templeton Foundation for financial support; A. Bear, R. Boyd, M. Crockett, J. Cone, F. Cushman, E. Fehr, M. Krasnow, R. Kurzban, J. Martin, M. Nowak, N. Raihani, L. Santos, and A. Shaw for helpful feedback; and A. Arechar, Z. Epstein, and G. Kraft-Todd for technical assistance.

Author information


  1. Department of Psychology, Yale University, New Haven, Connecticut 06511, USA

    • Jillian J. Jordan
    • , Paul Bloom
    •  & David G. Rand
  2. Program for Evolutionary Dynamics, Harvard University, Cambridge, Massachusetts 02138, USA

    • Moshe Hoffman
  3. Department of Economics, Yale University, New Haven, Connecticut 06511, USA

    • David G. Rand
  4. School of Management, Yale University, New Haven, Connecticut 06511, USA

    • David G. Rand


  1. Search for Jillian J. Jordan in:

  2. Search for Moshe Hoffman in:

  3. Search for Paul Bloom in:

  4. Search for David G. Rand in:


J.J.J., M.H. and D.G.R. designed and analysed the model. J.J.J., P.B. and D.G.R. designed the experiments. J.J.J. conducted the experiments and analysed the results. J.J.J., M.H., P.B. and D.G.R. wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Jillian J. Jordan or David G. Rand.

Extended data

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file contains Supplementary Text and Data – see contents page for details.


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.