Oligarchy ranks among the most widely used yet poorly theorized concepts in the social sciences. More than four decades ago, James Payne (1968) declared the concept a “muddle.” More recently, Leach (2005) applied the updated label “underspecified.” The International Encyclopedia of the Social Sciences defines oligarchy as “a form of government in which political power is in the hands of a small minority,” adding that it “derives from the Greek word oligarkhia (government of the few), which is composed of oligoi (few) and arkhein (to rule)” (Indridason 2008, 36). References to oligarchs and oligarchy abound, and yet the theoretical perspectives employed across cases and historical periods have very little in common. There is, for instance, minimal conceptual overlap in the application of the term to Filipino, Russian, and medieval oligarchs.

Mention of oligarchs is especially plentiful in the literature on postcolonial and postcommunist countries. However, the term occurs less frequently in advanced-industrial contexts, largely because oligarchy is generally thought to be overcome by electoral democracy. The dominant view among Americanists, for instance, is that pluralist democracies almost by definition cannot be oligarchic. The literature examining the many dimensions of minority power and influence in the United States, even when oligarchs are mentioned, centers almost entirely on elite rather than oligarchic forms of power – an important distinction further explained later in the chapter.