The strategic logic of costly punishment necessitates natural field experiments, and at least one such experiment exists

Costly punishment's scarcity "in the wild" does not belie strong reciprocity theory as Guala claims. In the presence of strong reciprocators, strategic defectors will cooperate and sanctioning will not occur. Accordingly, natural field experiments are necessary to assess a "wide" reading of costly punishment experiments. One such field experiment exists, and it supports the hypothesis that costly punishment promotes cooperation.