Arbitrary-set hierarchies emerge only once economic surplus is sustainable.

Evidence

1. While age and gender based hierarchies will tend to exist within all social systems, arbitrary-set systems of social hierarchy will invariably emerge within social systems producing sustainable economic surplus. — John T. Jost and Jim Sidanius, Political Psychology, 3183

Categorization

• DEFINE: Establishes the key scope condition distinguishing arbitrary-set from age/gender hierarchy.