A model of expertise

We study a model in which perfectly informed experts offer advice to a deci sion maker whose actions affect the welfare of all. Experts are biased and thus may wish to pull the decision maker in different directions and to dif ferent degrees. When the decision maker consults only a single expert, the expert withholds substantial information from the decision maker. We ask wh ether this situation is improved by having the decision maker sequentially consult two experts. We first show that there is no perfect Bayesian equili brium in which full revelation occurs. When both experts are biased in the same direction, it is never beneficial to consult both. In contrast, when e xperts are biased in opposite directions, it is always beneficial to consul t both. Indeed, in this case full revelation may be induced in an extended debate by introducing the possibility of rebuttal.