It's a Group-Eat-Group World: Social Dominance Theory in a Nutshell (aka a blog)

Countless theories focus on ways to reduce group inequalities (usually racism), but few try to explain why these inequalities, or hierarchies, exist.

Social Dominance Theory (Sidanius and Pratto, 1999) takes a dynamic stab at the difficult question: Why are hierarchies present in all societies at all points in human history?

Sidanius and his colleagues first distinguish between the three basic types of hierarchies: age-based (where the very young and very old have disproportionately less power than people in mid-adulthood), gender-based (in all species where there is sexual dimorphism with males being physically larger than females, males hold more power than females), and arbitrary set-based hierarchies (basically all other types of hierarchies where the different groups are not dependent on each other for continued survival).

Part of what makes Social Dominance Theory so dynamic is that it views hierarchy as emerging from an interaction between people in social contexts (otherwise described as a socioecological approach), rather than assuming relative independence of the individual from the situation.

At the individual level, the theory proposes there are predispositions toward viewing the world in dog-eat-dog, zero sum terms, where some people succeed and many fail; some groups dominate other groups. People who hold these beliefs tend to be more likely to tolerate and potentially promote group-based competition and inequality. This predisposition is often measured with the Social Dominance Orientation scale.

At the societal level, the theory proposes that there are two types of social agents.

1. Hierarchy-enhancing agents. Institutional agents include internal security forces including police, FBI, KGB, and similar entities, and profit-driven corporations. Individual agents are often the people who hold these occupations (see research showing a tendency for hierarchy-enhancers to choose jobs that promote hierarchy).
2. Hierarchy-attenuating agents. Institutional agents include charities, civil rights organizations, and public defenders' offices. Again, individual agents are often the people who hold these occupations (see occupational studies).

Hierarchy emerges as a function of these two countervailing forces, which provides one explanation for why some cultures are more hierarchical than others (the hierarchy-attenuating people and institutions are out-performing the hierarchy-enhancing people and institutions).

These components comprise the legitimizing myths that sustain a group hierarchies. Intervening between these myths and the actual construction of hierarchies are three mechanisms:

1. Aggregated individual discrimination. Individual discrimination appears in sometimes subtle ways like racial micro-aggression and other less subtle ways like choosing to hire someone of the dominant group for a position instead of someone from the subordinate group. When many individuals discriminate in this way, this creates group-based hierarchies. 
2. Aggregated institutional discrimination. Institutional discrimination appears in ways ranging from the subtle where minorities in the United States attending schools in poorer neighborhoods with less financial support to more extreme where minorities are given the death penalty in the legal system at higher rates than non-minorities even when looking at crimes of identical natures.
3. Behavioral asymmetry. Subordinate group members limit their behaviors in ways that do not benefit them. For example, minority group members are less likely to follow their doctors' advice and complete their medical treatment in accordance with the doctors' prescription. Subordinate group members also tend to engage in behaviors that make it more likely for them to be incarcerated or wounded (e.g., consuming and selling drugs, participating in gang violence). 

As you can tell, this complicated question has a complicated answer. But, at its most basic level, Social Dominance Theory argues that group-based hierarchies emerge in all cultures from the conflict between individuals and institutions that promote or attenuate hierarchy.