The doctoral dissertations written by Hou Yuon and Khieu Samphan express basic themes that were later to become the cornerstones of the policy adopted by Democratic Kampuchea. The central role of the peasants in national development was espoused by Hou Yuon in his 1955 thesis, "The Cambodian Peasants and Their Prospects for Modernization", which challenged the conventional view that urbanization and industrialization are necessary precursors of development. The major argument in Khieu Samphan's 1959 thesis, "Cambodia's Economy and Industrial Development", was that the country had to become self-reliant and had to end its economic dependency on the developed world. In its general contours, Khieu's work reflected the influence of a branch of the "dependency theory" school, which blamed lack of development in the Third World on the economic domination of the industrialized nations.