Qualification: Spillover Effects of Institutions on Cooperative Behavior, Preferences, and Beliefs
Engl, Riedl, and Weber provide direct evidence for the identification logic and an important boundary on it. Their laboratory study keeps the public-goods game structure constant across treatments, varies whether and how an enforcement institution applies, and measures effects relative to a no-institution baseline. This design permits causal statements about the institutional treatment. It supports Kaal's premise that a fixed task environment can isolate an institutional contribution. The qualification is material. Engl, Riedl, and Weber use controlled treatment contrasts. Kaal's claim describes a sequential stage arc. Keeping the population, task distribution, and harness fixed does not by itself remove period, learning, order, or carryover effects. The external evidence therefore supports the controlled-comparison principle, but it does not validate the exact stage sequence or the later inferences attributed to it.
research-methodsinstitutional-designscholarly-growth-coveragescholarly-literaturecausal-inferenceexperimental-economicsinstitutional-treatment