I Don’t Know

Political decision makers make choices in a complex and uncertain world, where even the most qualified experts may not know what policies will succeed. Worse, if these experts care about their reputation for competence, they may be averse to admitting what they don’t know. We model the strategic communication of uncertainty, allowing for the salient reality that sometimes the effects of proposed policies are impossible to know. Our model highlights the challenge of getting experts to admit uncertainty, even when it is possible to check predictive success. Moreover, we identify a novel solution: checking features of the question that only good experts will infer—in particular, whether the effect of policies is knowable—can induce uninformed experts do say “I Don’t Know.”