Local Evidence and Diversity in Minipublics

We study optimal minipublic design with endogenous evidence. A policymaker selects a group of citizens—a minipublic—for advice on the desirability of a policy. Citizens can discover local evidence but might be deterred by uncertainty about the policymaker’s adoption standard. We show that such uncertainty can be detrimental to evidence discovery even with costless evidence, civic-minded citizens, and ex ante aligned players. Evidence discovery is hardest to sustain under moderate uncertainty. The optimal minipublic has low diversity: it overrepresents citizens around the median citizen and underrepresents those at the margins. Our findings bear implications for the French Citizens’ Convention on Climate.