Social dominance theory (SDT) is a social psychological theory of intergroup relations that examines the caste-like features[1] of group-based social hierarchies, and how these hierarchies remain stable and perpetuate themselves.[2] According to the theory, group-based inequalities are maintained through three primary mechanisms: institutional discrimination, aggregated individual discrimination, and behavioral asymmetry. The theory proposes that widely shared cultural ideologies (“legitimizing myths”) provide the moral and intellectual justification for these intergroup behaviors[3] by serving to make privilege normal.[4] For data collection and validation of predictions, the social dominance orientation (SDO) scale was composed to measure acceptance of and desire for group-based social hierarchy,[5] which was assessed through two factors: support for group-based dominance and generalized opposition to equality, regardless of the ingroup's position in the power structure.[6]
The theory was initially proposed in 1992 by social psychology researchers Jim Sidanius, Erik Devereux, and Felicia Pratto.[7] It observes that human social groups consist of distinctly different group-based social hierarchies in societies that are capable of producing economic surpluses. These hierarchies have a trimorphic (three-form) structure, a description which was simplified from the four-part biosocial structure identified by van den Berghe (1978).[8] The hierarchies are based on: age (i.e., adults have more power and higher status than children), gender (i.e., men have more power and higher status than women), and arbitrary-set, which are group-based hierarchies that are culturally defined and do not necessarily exist in all societies. Such arbitrariness can select on ethnicity (e.g., in the US, Bosnia, Asia, Rwanda), class, cast, religion (Sunni versus Shia Islam), nationality, species or any other socially constructed category.[9][10] [11] Social hierarchy is not only seen as a universal human feature – SDT argues there is substantial evidence it is shared, including the theorized trimorphic structure – among apes and other primates.[12][13]