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Sociology of rural migration

Demographic transition (caused by the gap in time between the lowering of death rates from medical advances and the lowering of fertility rates), leads to population growth beyond the ability of housing, employment, public transit, sewer and water to provide. Combined with economic stagnation, urban agglomerations have been created in Cairo, Istanbul, Tehran, Karachi, Dhaka, and Jakarta, each with well over 12 million citizens, millions of them young and unemployed or underemployed. Such a demographic, alienated from the westernized ways of the urban elite, but uprooted from the comforts and more passive traditions of the villages they came from, is understandably favourably disposed to an Islamic system promising a better world —an ideology providing an "emotionally familiar basis for group identity, solidarity, and exclusion; an acceptable basis for legitimacy and authority; an immediately intelligible formulation of principles for both a critique of the present and a program for the future." One American anthropologist in Iran in the early 1970s (before the revolution), when comparing a "stable village with a new urban slum", discovered that where "the villagers took religion with a grain of salt and even ridiculed visiting preachers", the slum dwellers—all recently dispossessed peasants – "used religion as a substitute for their lost communities, oriented social life around the mosque, and accepted with zeal the teachings of the local mullah".

Gilles Kepel also notes that Islamist uprisings in Iran and Algeria, though a decade apart, coincided with the large numbers of youth who were "the first generation taught en masse to read and write and had been separated from their own rural, illiterate progenitors by a cultural gulf that radical Islamist ideology could exploit". Their "rural, illiterate" parents were too settled in tradition to be interested in Islamism and their children "more likely to call into question the utopian dreams of the 1970s generation", but they embraced revolutionary political Islam. Olivier Roy also asserts "it is not by chance that the Iranian Revolution took place the very year the proportion of city-dweller in Iran passed the 50% mark". and offers statistics in support for other countries (in 1990 Algeria, housing was so crowded that there was an average of eight inhabitants to a room, and 80% of youth aged 16 to 29 still lived with their parents). "The old clan or ethnic solidarities, the clout of the elders, and family control are fading little by little in the face of changes in the social structure..." This theory implies that a decline in illiteracy and rural emigration will mean a decline in Islamism.