Oligarchy (from Greek ὀλιγαρχία (oligarkhía); from ὀλίγος (olígos), meaning 'few', and ἄρχω (arkho), meaning 'to rule or to command') is a form of power structure in which power rests with a small number of people. These people may be distinguished by nobility, wealth, education or corporate, religious, political, or military control. Such states are often controlled by families who typically pass their influence from one generation to the next, but inheritance is not a necessary condition for the application of this term.
Throughout history, oligarchies have often been tyrannical, relying on public obedience or oppression to exist. Aristotle pioneered the use of the term as meaning rule by the rich, for which another term commonly used today is plutocracy. In the early 20th century Robert Michels developed the theory that democracies, as all large organizations, have a tendency to turn into oligarchies. In his "Iron law of oligarchy" he suggests that the necessary division of labor in large organizations leads to the establishment of a ruling class mostly concerned with protecting their own power.
This was already recognized by the Athenians in the fourth century BCE: after the restoration of democracy from oligarchical coups, they used the drawing of lots for selecting government officers to counteract that tendency toward oligarchy in government. They drew lots from large groups of adult volunteers to pick civil servants performing judicial, executive, and administrative functions (archai, boulē, and hēliastai). They even used lots for posts, such as judges and jurors in the political courts (nomothetai), which had the power to overrule the Assembly.
The exclusive consolidation of power by a dominant religious or ethnic minority has also been described as a form of oligarchy. Examples of this system include South Africa under apartheid, Liberia under Americo-Liberians, the Sultanate of Zanzibar, and Rhodesia, where the installation of oligarchic rule by the descendants of foreign settlers was primarily regarded as a legacy of various forms of colonialism.
The modern United States has also been described as an oligarchy because economic elites and organized groups representing business interests have substantial independent impacts on U.S. government policy, while average citizens and mass-based interest groups have little or no independent influence.