Max R. P. Grossmann

When is autonomy granted to a decision-maker conditional on their knowledge, and if no autonomy is granted, what form will the intervention take? We formulate a parsimonious formal theory about paternalistic intervention based on an absence of knowledge. This theory sheds light on how policymakers exploit decision-maker mistakes when these mistakes go in policymakers' subjectively preferred direction and when mistakes are used as a justification for intervention. In two experiments, policymakers (“Choice Architects”) can intervene in a choice faced by a decision-maker. The choice is between a fixed amount of money and a simple lottery. The first experiment varies the amount of ambiguity inherent in the lottery. We find that reduced ambiguity leads to fewer interventions in the decision-maker's choice. We conduct a high-powered followup experiment. Across both experiments, full decision-maker knowledge causes more than a 60\% reduction in intervention rates. Beliefs have a small but statistically significant effect. When Choice Architects are informed about the decision-maker’s preference, this information is used to determine the option imposed on the Chooser. However, Choice Architects employ their own preference to a similar extent as the decision-maker’s. Choice Architects are causally more willing to impose a riskless option, as if it were a bliss point, correlated with but conceptually distinct from Choice Architects' own preference. This is an important qualification to what has been termed “projective paternalism.” Choice Architects disproportionately prefer to have the decision-maker make informed decisions, even when they could exploit the decision-maker's ignorance. However, interveners are less likely to provide information. As predicted by theory, the same applies to Choice Architects who believe that mistakes go in the direction of their own preference.