Chapter 3 introduces several models of politics and public policy. One model, pluralism, deals with the role of interest groups and asserts that many (plural) sources of political power exist in society and that no one source of power or single interest group is dominant across the range of public decisions. The reason is that interest groups specialize in certain policy areas, so groups having influence in one area, such as health care, are not necessarily involved in or influence another policy arena, such as national security. This view of politics contrasts with elite theory, which states that certain powerful organizations (elites) have power and authority over all policy arenas.