Rating rules in the helping game: An axiomatic approach

We examine a stylised helping game in which players recurrently decide whether to help others at personal cost and are assigned binary ratings of “helpfulness” based on previous choices. We propose axioms requiring that ratings are responsive to players’ decisions and change monotonically with respect to helping given or withheld. Only four rules satisfy these axioms: two standing rules and two versions of a form of binary image scoring. These results show how a single rating can encode both the “desert” perspective, linking worthiness to kindness and deservingness, and the “club” perspective, relating worthiness to a cooperative club’s membership. • We examine the principles underlying binary rating rules in a stylised helping game. • The implications of six natural axioms on rating rules are identified. • Only four out of 256 potential binary rating rules satisfy the axioms. • These include two standing rules, binary image scoring, and a modified version of it. • Binary ratings can thus encode both the “desert” and “club” normative perspectives.