1. The basic idea At the end of the 19 th century several French scholars noted that a remarkable change was taking place in the population of their country. The number of children per family declined, clearly as the result of deliberate efforts to reduce fertility within marriage. It was soon understood that the voluntary limitation of marital fertility was a revolutionary novelty and the term 'demographic revolution' was, in fact, the original term used to describe it. Efforts to explain what was happening began almost immediately. Interestingly enough these first explanations assumed the phenomenon reflected what people wanted out of life. Dumont (1890:130) argued that the desire to be upwardly mobile was the root cause. When climbing the social ladder having a large family would be, no doubt, a hindrance. Dumont concluded that, as a result, the birth rate would decline as social mobility increased. Other French authors, such as Leroy-Beaulieu (1896) and Landry (1909) attributed it to changes in the moral order. Towards the end of the Second World War, and also after it, American scholars took de lead in the discussions about the demographic changes that were taking place. As a result the explanations preferred became more economic in nature and the term 'transition' replaced the term revolution. The changes in demographic behaviour were considered to be mainly a function of progress in society (Kirk, 1944:28). Notestein (1945), who played a crucial part in the formulation of the demographic transition theory, stressed the overriding importance of mortality decline and the impact of the modernization process in people's lives and in society as a whole. He concluded that the demographic transition was likely to be a universal phenomenon; all countries were bound to pass through it once they had achieved the level of development required. It was understood by all knowledgeable people that the decline in fertility was an adjustment made necessary by the decline in mortality. The latter had resulted in unsustainab...