AGREEMENT, AND SYNERGY UPDATING ON THE CREDENCES OF OTHERS: DISAGREEMENT

2016, Easwaran, Fenton-Glynn, Hitchcock, and Velasco. We introduce a family of rules for adjusting ones credences in response to learning the credences of others. These rules have a number of desirable features. 1. They yield the posterior credences that would result from updating by standard Bayesian conditionalization on ones peers reported credences if ones likelihood function takes a particular simple form. 2. In the simplest form, they are symmetric among the agents in the group. 3. They map neatly onto the familiar Condorcet voting results. 4. They preserve shared agreement about independence in a wide range of cases. 5. They commute with conditionalization and with multiple peer updates. Importantly, these rules have a surprising property that we call synergy - peer testimony of credences can provide mutually supporting evidence raising an individuals credence higher than any peers initial prior report. At first, this may seem to be a strike against them. We argue, however, that synergy is actually a desirable feature and the failure of other updating rules to yield synergy is a strike against them.

UPDATING ON THE CREDENCES OF OTHERS: DISAGREEMENT, AGREEMENT, AND SYNERGY Academic Article