Moral judgments, ideas about good or bad, remain the building block of cooperation in a large group.

A rule of thumb for promoting cooperation is to help those who have a good reputation and not those who have a bad reputation, yet that determination requires time, effort and money. What about moral "free riders" who evade the cost associated with moral judgment (e.g. by not paying taxes for police and court) so are better off than those who shoulder the cost?

Philosophers debate voluntary reactive policing of the moral free riders, which is costly, too, and thus can be exploited by higher order moral free riders. This leads to an infinite regression of opportunities to free ride.

Can the moral free rider problem really be solved? 

In a recent paper, Tatsuya Sasaki, Isamu Okada (Soka University, Tokyo) and Yutaka Nakai (Shibaura Institute of Technology, Saitama) consider pre-assessment of the moral free riders. Sasaki and his colleagues devise an extra assessment system that offers an option to contribute to a pool account of the moral cost in advance. This is aimed not only at funding but also at detecting and labeling those who are not willing to pay for justice prior to the social exchange. In social exchanges, the labeled individuals will be refused help. Through game-theory analysis, this study finds that pre-assessment leads to stabilizing a costly moral system and thus cooperation.

This has an important implication to contemporary issues. How good and bad are determined, in fact, varies among individuals with different moral standards. Sasaki and his colleagues believe that the pre-assessment could be the common feature for sustaining the moral system, irrespective of its moral code. "Our findings suggest that different individuals may not agree on what justice is but may arrive at a consensus about how justice is maintained. The results of future work that investigates to what extent the pre-assessment affects moral diversity will be fascinating," says Sasaki.