Invited Talk: Follow the money, not the majority: Incentivizing and aggregating expert opinions with Bayesian markets

For some questions, such as whether extraterrestrial life exists, it is uncertain if and when the answer will be known. Asking experts for their opinion yields two practical problems. First, how can truth-telling be incentivized if the correct answer is unknowable? Second, if experts disagree, who should be trusted? This paper solves both problems simultaneously. Experts decide whether to endorse a statement and trade an asset whose value depends on the endorsement rate. The respective payoffs of buyers and sellers indicate whom to trust. We demonstrate theoretically and illustrate empirically that ``following the money" outperforms selecting the majority opinion.