Social Preference behind the Veil of Ignorance, Experiments Conducted on Formosan Rock Macaques

Rawls (1971) argued that a just society could be constructed by the way that people choose their ideal wealth distribution behind the veil of ignorance which keeps agents uninformed of their social status. Past study had presented that human subjects had stronger social preference of inequity aversion when behind the veil of ignorance compared with the situation in front of the veil. However, there still lacks empirical evidence associating preference behind the veil with preference in front of it. Moreover, evidence for the evolutionary issue whether social preference is specific to humans or shared with our genetic relatives, primates, were still divergent; thus, preference behind the veil provides new evidence to probe into their true social preference. In this study, we implemented a series of modified dictator games on Formosan Rock Macaques (Macaca cyclopis) to measure their social preference in front of and behind the veil as well as their risk preference. The result showed that our subjects had social preference both in front of and behind the veil; further, preference behind the veil can be partly explained by the preference in front of the veil. Our finding supports that humans’ social preference may evolve from the common ancestor shared with other primates.