Abstract

Adam Elga has argued that holders of imprecise credences fall prey to missed arbitrages, so that rational credences should be sharp. A decision rule proposed by Rohan Sud, Forward Looking, enables imprecise Bayesians to sidestep missed arbitrages and other ``bad books'' in isolated fixed-evidence binary betting sequences such as those of Elga. We show that Forward Looking imprecise Bayesians are committed to a bad book of bets when faced with a particular 3-bet variable-evidence binary betting sequence.