Harry C. Triandis

“Number of Ingroups If only one ingroup is present, it dominates social life. It provides the only source of norms, identity, and social support. Collectivists may have relatively few ingroups, but they identify very strongly with them. The ingroups of collectivists provide social insurance, protection, and a relaxing atmosphere. The presence of many ingroups encourages individualism. For example, the separation of church and state in the United States automatically creates more than one ingroup and is a premise upon which multiculturalism and democracy are based. It is also the foundation for social movements because each ingroup can potentially become a social movement. Multiple ingroups are especially important in large urban centers, where the social controls of small ingroups are often weak. The social structures of these communities are loose, and several of the factors we have discussed converge to put more emphasis on personal responsibility and less on norms. With more ingroups and looseness there is an increase in social diversity, tolerance for deviance, and multiculturalism. Thus the factors that make cultures loose and allow many choices favor individualism. Conversely, collectivism is maximal in tight cultures, where there are few choices.”
― Harry C. Triandis, Individualism And Collectivism