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Basic Concepts on Fertility Theories

basic-concepts-of-fertility

DENSITY PRINCIPLE OF (MICHAEL THOMAS, 1830)

 Michael Thomas Sadler propounded the ‘density principle’ in his two-volume work entitled The Laws of Population, published in 1830. Though much of his work was aimed at refuting the arguments of Malthusians, he did make an attempt to outline a theory of population which he called the true law of population. According to Sadler, fertility varies inversely with the density of the population. In other words, “the prolificacy of a given number of marriages will, all other circumstances being the same, vary in proportion to the condensation of the population”. 

SOCIAL CAPILLARITY THEORY (ARSENE DUMONT, 1890)

 According to Dumont: one has an urge (force) to rise and improve his social status. He compared the urge to rise in the social scale to the inevitable (incapable) physical law of nature – the force of a capillarity. As a column of liquid has to be thin in order to rise under the force of capillarity, so a family must be small in order to rise in the social scale. 

THEORY OF INCREASING PROSPERITY (L. BRENTANO, 1910)

 In 1910, L. Brentano presented another explanation of fertility differentials in his theory of increasing prosperity. According to Brentano, the key to fertility differences is rooted in the differences in material prosperity of different peoples. He argues that man is essentially a creature of pleasure, the sources of which vary from group to group. The poor with an extremely restricted number of alternative pleasures tend to find compensation for this deprivation in sexual indulgence. 

THE DIET PRINCIPLE (THOMAS.A.DOUBLEDAY, 1941)

 In 1941, Thomas A. Doubleday propounded the ‘diet principle’ in his book The True Law of Population. While experimenting with plants, Doubleday found that an excessive application of manure “invariably induces sterility in the plant, and if the doses were increased, disease and death” 

UTILITY THEORY OF FERTILITY (LEIBENSTEIN, 1957) 

In his famous book, Economic Backwardness and Economics Growth, formulated the utility theory of fertility. According to this theory, people make rough calculations about the number of children they desire, based on the utilities and dis-utilities of children. These calculations take into account the balance between the satisfactions or utilities obtained from an additional child and the “cost”, both monetary and psychological, of having an additional child. 

THE QUANTITY-QUALITY TRADE-OFF (GARY BECKER, 1960)

 He extended the economic analysis to the new area of reproductive behaviour. Applying the neo-classical micro-economic model of consumer choice, Becker postulated that parents choose the optimum number of children, which balances the utility, which they derive from the children against budget constraints. The budget constraint reflects the wage rate of labour and the prices of different goods and services. Thus the problem of deciding family size is purely economic. The effect of an income change on the demand for children: Assuming children and the standard of `child quality’ to be `normal’ goods, an increase in income will cause families to demand not only more children but also better quality children. In a nutshell, an increasing marginal cost of quality (child outcome) with respect to quantity (number of children) leads to a trade-off between quantity and quality 

THEORY OF CHANGE AND RESPONSE (KINGSLEY DAVIS , 1963)

 This theory was propounded to explain the decline in birth rates in developed countries. The process of demographic change and response is not only continuous but also reflexive in the sense that a change in one component is eventually altered by the change in other components. 

UNITED NATIONS THRESHOLD HYPOTHESIS (1963)

 In 1950’s and 1960’s less developed countries did not exhibit declining fertility levels despite improvements in socioeconomic conditions. The U.N. threshold hypothesis was presented to explain this anomaly.

According to this hypothesis, in the early stages of development, small changes in socioeconomic levels would have no bearing upon fertility levels. It is only when the socio-economic indicators reach a minimal level that further improvement in them will bring about changes in fertility levels. In other words, there are threshold values of development indicators, which will indicate the onset of fertility decline. 

THEORY OF DIFFUSION OR CULTURAL LAG (GOSTA CARLSSON, 1966)

 This theory explains how the innovation of birth control and the concept of birth control speedily spread over the world. According to the cultural lag theory of fertility differential, in countries where fertility has been declining, attitudes and practices to diminishing fertility have been adopted first by the better-educated, wealthier, and socially more advanced groups of the city population and transmitted in the course of time to intermediate and lower status groups and to the rural areas. 

EASTERLIN’S FRAMEWORK (1975),

 Easterlin’s synthetic framework of fertility determinants is an integration of economic and sociological approaches. His theory acknowledges that the couple’s reproductive capacity is a condition beyond the control of the family as it is constrained by the familial environment, which is not within the decision-making purview of the family. 

WEALTH FLOWS THEORY (CALDWELL, 1976)

 This theory was propounded to explain the fertility behaviour of the population in developing countries. The wealth flow is in terms of the flow of money, goods and services from children to parents and vice versa. According to him, lifetime net inter-generational wealth flow would determine the levels of fertility of the population. From the demographic point of view, fertility is high when the net economic advantage from children is high and low when the net flow of wealth is high from parents to children. Fertility starts declining when there is a reversal of the net flow of wealth. 

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