Ingroup vs Outgroup Dynamics
Definition
Terje Bongard:
"Ingroups and outgroups are not easy to define properly, but an ingroup is functional if all members know each other and can freely look into each member’s actions. Beyond a certain size (maybe 20-50) the control exercised by the individuals fail, and outgroup strategies begin to dominate, like Tragedies of the Unmanaged Commons etc ...". (cfr. The Biological Human)