If Bob and Alice prefer vanilla to chocolate ice cream then when given the choice we wouldn’t be surprised to see each of them choosing vanilla. Now suppose that Bob and Alice are given the following choice, if either chooses vanilla they both get vanilla only if both choose chocolate do they receive chocolate. If Bob and Alice prefer vanilla to chocolate it seems plausible that they will continue to choose vanilla. But suppose that we observe Bob and Alice choosing chocolate in the second experiment. How might we explain this?
Imagine that chocolate is considered sinful and vanilla is thought to be nice. Bob and Alice might want to be sinful but they choose nice in the first experiment to avoid social condemnation. In the second experiment, however, Bob and Alice are sinful only when both sin. True preferences are revealed only when no individual can be singled out for condemnation.
That’s the setup of one of the clever experiments in an excellent new paper, Exploiting Moral Wiggle Room, except the experiment isn’t about chocolate and vanilla ice cream it’s about fairness in a division game. In the first experiment Alice and Bob must each decide whether to choose $6 for themselves and $1 for a third party (Cindy) or $5 for themselves and $5 for Cindy. In this experiment most Alice and Bobs choose to be nice, they divide "fairly" with Cindy. Many researchers have concluded that Alice and Bob must have a preference for niceness.
But put Alice and Bob together in the second experiment and Alice and Bob are each much more likely to choose the sinful division, $6 and $1. Alice and Bob may prefer chocolate after all.
Read the paper for several other experiments along these lines. The implications for societal organization are profound.
Hat tip to Robin Hanson.