Third parties incur costs to punish norm violations they do not directly suffer. [causal]

    Third parties incur costs to punish norm violations they do not directly suffer. [causal]
  

We hypothesize that egalitarian distribution norms and cooperation norms apply in our experiments, and that third parties, whose economic payoff is unaffected by the norm violation, may be willing to enforce these norms although the enforcement is costly for them.

DEFINE: Defines 'altruistic third-party punishment' — where an unaffected bystander pays to enforce norms.
Ernst Fehr, Third-Party Punishment and …, loc. 2