Theories of modernisation, like theories of political development, are based on the assumption that societal change is a linear process involving the transformation of traditional, agrarian societies into modern, industrial societies. The nation-building school represents a significant attempt to bring values into the developmental process, particularly as applied to the Third World. Huntington and Organski shifted the focus of development and modernisation theory from a progression towards democracy to a concern with political stability and the role of government in the modernisation process. David Apter in 'The Politics of Modernisation' adopted a structural-functional approach and sought to incorporate communist systems in one of two models of modernisation. It is this degree of interdependence that has produced the most effective criticism of development and modernisation theory the related schools of underdevelopment and dependency. The historical relationship between capitalist societies and the Third World is more complex than underdevelopment and dependency theories imply.