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This article throws light upon the top eight theories of population. Some of the theories are: 1. Thomas Doubleday’s Diet Theory 2. Jouse De Castro’s Protein Consumption Theory 3. Michael Thomas Sadler’s Destiny Theory 4. Herbert Spencer’s Biological Theory 5. Corrado Ginnis’s Biological Population Theory and Others.
1. Thomas Doubleday’s Diet Theory:
Thomas Doubleday, a social philosopher and an English economist, was born in 1790. He expressed his views regarding various natural laws which govern population. According to him, the rate of population increase will be less when the quantity of food supply is greater.
It means that the increase in population and food supply are inversely related. Doubleday mentions two states of food supply, i.e., (i) The Plethoric state having good food supply where the fertility is low, and (ii) the Deplethoric state in which due to food shortage we find diminution of proper nourishment where the fertility is high.
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According to Doubleday, fertility is affected by leanness in all plants and animals. An overfed plant can be revived only when the plants are depleted either by ringing the bark or by extreme lopping or the trenching of the roots.
Besides, the sterility in plant life is possible when the application of fertilizers is excessive. He also believes that thin birds or animals give birth to more offspring, while bulky or fat birds or animals give birth to less. Similarly, this becomes true about trees and plants. It means that fertility depends on the fatness of living beings, according to Doubleday.
Moreover, Doubleday also observes that high fertility has been found in those persons who are vegetarians, or who eat more rice or whose staple diet is rich, whereas fertility will be low in non-vegetarian persons.
Doubleday divides society into three groups:
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(1) The first group includes those who are in a state of affluence and are well supplied with luxuries. Their number is on constant decrease. While the number of those who are engaged in mental or physical activities and are living busy life, is on the increase.
(2) The second group consists of the poor people who have less supply of food. Their number is increasing rapidly. In other words, the constant increase in population is found in the group where people are worst supplied with food. This happens in all societies.
(3) The third group has those people who form the mean and median between two opposite states and who fall under the average income group and those who are tolerably well supplied with good food or who get a normal diet and do not overwork and yet are not idle. Their number is stationary.
Doubleday concludes that “it is upon the numerical proportion which these three states bear to each other in any society that increase or decrease on the whole depends.”
Doubleday is also of the view that, “The rich produce less children as the fertility would be less amongst them and therefore, the transfer of their wealth will be distributed among a few People. Over a period of time, it may happen that there is no one as an heir to that property and therefore this wealth will pass to the children of the poor. Again when the children become rich, they will restrict their families and their wealth will be gained once again by the poor. Thus socialism comes on its own through the automatic distribution of wealth by nature.”
Criticisms of Thomas Doubleday’s Diet Theory:
Thomas Doubleday’s diet theory has been criticised on the following grounds:
1. Doubleday’s observation regarding an inverse relationship between food supply and fertility has no scientific basis.
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2. According to Doubleday, the fertility is low in the Plethoric state due to good food supply and is high in Deplethoric state due to food shortages and diminution of proper nourishment. However, such things have not happened in reality. Even in Plethoric state the population goes on increasing.
3. Doubleday believes that the rich people have less children whereas the poor have more. In reality, this is far from true, because in many cases we find more children in rich families and less in the poor ones.
4. Doubleday opine that the number of those persons who get a normal diet and who come under the average income group remains stationary. But experiences has shown that even in such an income group the number has always been increasing.
5. Doubleday is of the view that fertility depends on fatness. As the rich persons are fat, fertility is low with the increase in fatness. In this regard, Spencer has criticised this presumption of Doubleday. According to him, in reality every rich person may not be always fat.
Spencer felt that fatness does not fully depend on good food but the root cause of fatness is bad digestion. At present, the rich persons are more conscious about their health and their families and with the help of gyms and health clubs and medical facilities, they keep themselves away from fat and maintain health.
6. Doubleday is of the opinion that socialism will come on its own through the automatic distribution of wealth by nature. This argument does not have any scientific support of distribution of wealth and thus it cannot be said to be true.
7. In Doubleday’s diet theory there is confusion between fertility and fecundity. While criticising the theory of Doubleday, Thompson and Lewis have said that there is no scientific basis for the belief that the proportion of protein in the diet or the relative abundance of intake of calorie has any noticeable effect upon fecundity. The actual bearing of living children, that is fertility of any population, may be affected substantially by the use of contraceptives as preventive checks while fecundity remains unchanged.
2. Jouse De Castro’s Protein Consumption Theory:
Jouse De Castro expressed his views in his famous book The Geography of Hunger regarding the correlation between the fertility and the consumption of protein. Castro accepted the findings of R.J. Solankar who conducted experiments on rats in 1920. In these experiments Solankar found that with the increase in protein consumption in diet, the fecundity will decrease and it will increase with low protein content in diet.
His experiment led to the following conclusions:
(i) When 10 per cent protein was given to a female rat, per mated female rat gave 23.3 births;
(ii) When 18 percent protein was given to each female rat, per mated female rat gave 17.4 births; and
(iii) When the quantity of protein was increased to a level of 22 percent to each female rat, the birth per mated female rat reduced to 13.8 births.
Through these experiments Castro came to the conclusion that the fatness is affected by the consumption of protein. The fatness increases with the protein rich diet, which leads to lower fertility. This concept of Castro is similar to the Doubleday’s diet theory that the rate of population increase is influenced by food supply.
Moreover, Castro also found a direct relation between the functioning of the liver and that of the ovaries.
In the words of Castro, “It is known that there is a direct connection between the functioning of the liver and the ovaries, the role of the liver being to inactivate the excess estrogens which the ovaries throw into the blood stream. Fatty degeneration of the liver and the tendency to cirrhosis are some of the characteristic result of protein deficiency when degeneration of the liver occurs, it begins to operate less efficiently, and is less effective at its job of inactivating excess oestrogents. The result is a marked increase in the women’s reproductive capacity.”
According to Castro, balanced food is not available to the poor and therefore poor people are always getting less protein in food which results in sluggish liver function. Consequently, when males have defective liver, the estrogens in women’s body cannot be neutralised, and with the increase in estrogens the women’s reproductive capacity increases. This results in high birth rate. Therefore, compared to the rich, the birth rate in the poor people with chronic hunger (malnutrition) is high. But in the case of acute hunger, sexual activity goes down.
According to Castro, people or societies are blamed for the high birth rate in the poor countries, which is not proper. For this the rich countries or the people of affluent societies should be blamed, because the imperial or colonial powers have not taken any steps to improve the standard of living of their people nor have they made attempts to provide good food.
On the contrary, instead of concentrating more on the increase of food production, imperial powers have concentrated on the purchase of raw materials and food supplies at low rates and finished products have been sold out at high rates in their colonies.
As a result, due to high prices and low wages, the people’s food intake becomes imbalanced and they cannot get enough protein content in their diet. With the reduction or absence of protein contents in their food, the capacity to produce more children increases which ultimately results in the increase in poverty. When poverty increases, again due to the imbalanced food, people get less protein, which again leads to the increase in the capacity to produce more children. Such a vicious cycle goes on.
It was painful for Castro when he observed that adequate attention had not been given to the problems of the imbalance food by the rich, the capitalists, the scientists or the imperialists. They had given importance only to the commercial activities rather than to the social aspects of poverty.
Castro reflected on the issue with reference to India that out of the total number of children born in India, almost fifty percent suffer from starvation and die before they reach the age of marriage.
On the basis of data for different countries relating to the association of fertility with consumption of protein, Castro concluded that in 1952 two-third of the world population experienced chronic hunger, i.e., malnutrition, disease or early death.
According to him, the fertility rates can be reduced only if more attention is paid to grow more food crops than commercial crops which are made available to the poor people. In the words of Castro, “when deserts of ice and impenetrable jungles are being turned to gardens and orchards, when the lands we farm and the plants we grow are being made to multiply their field, and while we are barely learning how to tap the great food reservoirs of water, the wild flora and of artificial synthesis, the Malthusians go on setting up their sinister scarecrows. It is nothing to us, since we have reasons to fear them.”
Castro pointed out that to eradicate chronic hunger, priority should be given to the problem of balanced food. Efforts should be made to bring more lands under the plough with improved farming methods and extensive cultivation.
This is only possible through economic development leading to rising income of the poor which increases their protein consumption.
Criticisms of Jouse De Castro’s Protein Consumption Theory:
Castro’s theory of protein consumption has the following defects:
1. High fertility has been experienced in many developed countries with the increase of protein in diet.
2. Scientifically, it cannot be proved that protein rich diet leads to lower fertility.
3. Fertility always does not increase in poor people because it is not true that chronic hunger will always give more importance to sex.
4. In poor countries, the reasons for high birth rate are poverty and imbalanced food. However, factors like agriculture based economy, social, religious or cultural structure of the society, education, existence of joint family system, marriage at early age, etc. cannot be ignored in influencing population growth.
5. Economists do not accept the view that human fertility depends on diet alone. According to Coontz, fluctuations in fertility during trade cycle cannot be explained in terms of diet.
6. Castro’s view that with economic development fertility can decline has been criticised by Leibenstein. According to him, “The reasons why this approach is fallacious is that the economy might not have experienced sustained development if fertility rates had not declined at some crucial stage during the expansion.”
7. Thomson and Lewis have critcised Castro for the relation between diet and fecundity. According to them, there is no scientific basis for the belief that good diet or relative abundance of calorie intake have any noticeable effect upon fecundity. Rather, fertility may be affected by the preventive checks of various kinds, while fecundity remains unchanged.”
3. Michael Thomas Sadler’s Destiny Theory:
Michael Thomas Sadler, an Economist and a British social reformer, was born in 1780. He was a contemporary of Malthus. He expressed his ideas about population in his book The Law of Population. According to Sadler, the law which regulates the growth of animals and plants is primarily the same as the law which regulates the growth of human population.
He was of the opinion that “The fecundity of human beings is in the inverse ratio of the condensation of their numbers.”
Moreover, the fertility rate decreases with the increase in the density of population. In the agriculture based or pastoral countries where the density of population is low, the fertility rate of the population becomes high. In such countries, people have the capacity to work hard and hardworking people give birth to more children.
With the passing of time, when there is industrialisation and the population becomes more civilized and literate, the density of population increases. Here people would limit the size of family and in such socio-economic conditions they will be happier and there will be prosperity.
Sadler was a great critic of Malthus. He did not accept Malthus’s view that population increases in geometrical progression and food supply increases in arithmetical progression. According to Sadler, such increase of population and food supply in mathematical terms just cannot happen, because when population increases density too will increase.
And when density increases, the capacity to produce children goes down and thus with the increase in density, the fertility rate declines. He believed that population adjusts itself with the times.
He did not accept the fear of Malthus that positive checks by nature take place with the growth of population. He also did not believe in the preventive measures of birth control described by Malthus. Sadler was very optimistic and he tried to establish a link between population and food supply.
He was of the view that if the fertility rate of population increases, people will be able to produce food according to their needs and the food supply and population will get adjusted to each other.
Sadler also believed that when the density of population increases the unhealthy atmosphere also increases which leads to the increase in the death rate. Further, if the death rate is high, it will lead to increase in the birth rate. This happens to compensate for the loss of population. And if the death rate is low, the birth rate also goes down.
Criticisms of Michael Thomas Sadler’s Destiny Theory:
If we compare Sadler’s theory to the Malthusian theory of population, it can be said that the theory of Sadler is very optimistic. When Sadler’s book was published in 1830, many economists, sociologists and demographers were under the spell of pessimism created by Malthus in his population theory. In such an atmosphere to give optimistic thoughts itself was a great achievement.
But the theory of Sadler is also criticised on different grounds:
1. Sadler failed to distinguish between fecundity and fertility. He said that the fecundity of human beings is in the inverse ratio of the condensation of their numbers. But in fact no biological reason is found to prove the idea that if density brings down ‘fertility’, it will bring down ‘fecundity’ also. This is because in slums the density is very high and at the same time fertility is also high among slum dwellers.
2. Moreover, in many countries of the world where the density is high, the fertility rate is also high. Even in India, in some states like Delhi, Kerala and West Bengal where the density is high, the fertility is not low in comparison with the fertility of other states.
3. Another point of criticism is the paradoxical statement of Sadler that with the increase in density, the fertility rate decreases. At the same time, he was of the view that with the increase in density the death rate will increase and consequently, to compensate for the loss of population the fertility rate also increases.
It means that the fertility rate will not decrease, but it will increase with the increase of density. Thus, Sadler’s statements are self-contradictory.
4. Sadler’s view that with industrialization the population decreases has not been proved true. In a country like India, industrialisation has not led to the decline in the growth of population.
4. Herbert Spencer’s Biological Theory:
Herbert Spencer, a famous English philosopher and sociologist, propounded the biological theory of population in his book The Principles of Biology. Spencer argued that fecundity decreases when the complexity of life increases.
According to him, changes in the growth of population occur due to natural change in the reproductive capacity of human beings. Therefore, his theory has been known as a natural theory of population which is similar to the theory of Sadler and Doubleday.
Spencer believed that “there exists antagonism between individuation (survival) and genesis (reproduction)”. When any individual does hard work for his personal development at his work place, the desire for reproduction decreases.
In other words, when more energy has been utilised for one’s self-development, the energy available for reproduction will be less and consequently the population growth will be less. Thus, with the development of society and for one’s success and survival (individuation), life becomes more complex which results in reduction in the capacity of reproduction.
This is observed from the fact that fertility is more in rural individuals whose life is not complex, whereas fertility is low in an industrial society where life is more complex, the pressure of education is more and the brains are overtaxing.
We have four different situations which explain the relation between individuation and genesis:
(i) The individuation will automatically below when there is high genesis. This situation we find among the poor.
(ii) The genesis will be low when there is high individuation. Such a situation we find among the rich.
(iii) The individuation will improve when the genesis is low.
(iv) The genesis will be high when the individuation is low. In poor people, we find less individuation and more genesis.
Moreover, because of high fertility the individuation will be low and therefore the death rate will increase. At the same time because of low individuation, the expectancy of life will also decrease. To Spencer, the expectancy of life can be increased, when the birth rate decreases.
Spencer’s theory of population is based on the theory of evolution. According to Spencer, the fertility rate is higher in small creatures. In the words of Spencer, “The minutest organisms multiply asexually (without sex) in their millions.” Many small cells do not reach the maturity period.
If this happens and small cells grow in number twice or thrice, population will rapidly increase and multiply itself. Small compound cells get increased in thousands, while big compound cells in hundreds and still bigger cells lose their productive capacity. In the same manner, Spencer explained the fertility of human beings.
According to him, people can be divided in three groups:
(i) Poor people who live a simple life whose fertility is high;
(ii) Middle class people whose fertility is correspondingly low; and
(iii) People who live developed or complex life whose fertility is fairly low.
According to Spencer, in societies where people, especially woman, are educated and belong to rich families, their reproductive power is low, as compared to the poor who are uneducated and whose reproductive power is high.
In the words of Spencer, “In its full sense, the reproductive power means the power to bear a well-developed infant, and to supply that infant with the natural food for the natural period. Most of the flat chested girls who survive their high- pressure education are incompetent to do this. Were their fertility measured by the number of children they could rear without artificial aid, they would prove relatively very infertile.”
Spencer believed that if population increases we get more manpower through which natural resources can be exploited and the socio-economic and cultural standards of the people can be raised. Thus, he was of the opinion that increase in population was beneficial rather then harmful.
Further, as per Spencer, a determining factor for birth fate and death rate is longevity. The expectancy of life increases and the death rate decreases when life becomes more complex. He, therefore, suggested increase in life expectancy in order to reduce the birth rate.
Criticisms of Herbert Spencer’s Biological Theory:
Spencer’s theory of population has been criticised on the following counts:
1. Spencer’s population theory is not a real theory but a biological theory.
2. The view of Spencer that fertility decreases due to more complex life has no empirical evidence. There is high fertility rate even in rich families or industrialised societies where people’s life is more complex.
3. The problem of population growth itself is a complex phenomenon and therefore it cannot be explained as a biological one.
4. Spencer’s view that educated women whose individuation is high would prove relatively infertile, is not realistic. Even educated women have high reproductive power.
5. Spencer’s theory that fertility is affected by the natural process of individuation has no justification because when Spencer propounded this theory the birth rate was high in the western countries.
5. Corrado Ginnis’s Biological Population Theory:
Corrado Ginnis, a sociologist, was born in Italy in 1884. He had deep interest in the study of population changes which affect the evolution of society and that of a nation. According to Ginni, fertility will be very high in a nation when it is in the primary stage. Due to high fertility, the population increases and consequently social and economic problems become complex.
Further, the problems of trade and industry also become more complex.
At this time, fertility starts declining. “He thought that the evolution of a nation or any society was closely linked to the changes in their rates of population growth and to the varying propositions of this growth coming from the different social classes.”
Ginni was of the opinion that only biological factors are responsible for the increase in population and therefore his theory of population can be characterised as a natural law theory. According to Thomson and Lewis, “Ginni invokes some mystical biological changes, quite beyond man’s control, as the basic factors determining not only man’s quantitative growth, i.e., his fertility, fecundity, and survival but also his qualitative development, i.e., the distinctive characteristics of man’s different civilization.”
Moreover, the biological traits of population change at various rates of increase in the different classes of population. According to Ginni, “There is first a period of slower growth and mature achievement which, in turn, passes into a period of senescence, during which numbers decline and the quality of utilization deteriorates.”
Ginni was of the view that social and economic factors can influence the population growth but the reasons for the increase or the decrease in population growth are only biological. Thus this theory is based on biological aspects.
According to Thomson and Lewis, “Ginni believed that the biological factor in declining fertility was the fundamental factor, that it really underlays the influence of economic and social factors, which only apparently determined the decline in fertility.”
Ginni believed that the population growth is similar to the cyclical growth of an individual. In the first stage, the growth of population is very rapid while in the second stage, the growth is comparatively slow. In the third stage which is known as senescence, population decreases and there is deterioration in the quality of civilization.
As pointed out by Thomson and Lewis, “Every nation in its youth is simple and undifferentiated in structure and has a high rate of fertility, because each generation springs from the people who are hereditarily most prolific, i.e., highly fecund.”
Ginni was of the opinion that due to high fertility population increases and consequently social and economic problems become complex. Along with that industrial and trade problems also become more complex, the pressure of population is ultimately reduced through war or colonisation or both.
According to Ginni, first the fertility rate declines among the rich. After that when the energetic and prolific poor people enter the rich class, their fertility also decreases. When the whole society or country becomes rich, there is decline in population growth due to the weakening of the reproductive instinct.
Ginni concludes:
“It is a providential mechanism for the elimination of those family stocks which have fulfilled the cycle of their evolution.”
6. Dumont’s Theory of Social Capillarity:
Arsene Dumont (1849-1902) has propounded the Theory of Social Capillarity. Social attraction or repulsion to a thing is known as Social Capillarity. Dumont studied the growth of population in France in the later part of nineteenth century and found that the reason for low fertility in France was high intellectual and aesthetic development.
In the words of Dumont, “The development of number in a nation is in inverse ratio to the development of individual.”
According to him, “The direct cause of decline in birth rate was the movement of individual from the lower to the upper class.The individual tends to rise to higher levels in his social environment by process similar to physical capillarity.” Further, “what gravity is to the physical world, capillarity is to the social order.”
According to Dumont, there are three principles of population that are related to the stages of social development:
1. In the preventive stage, the Malthusian theory of population applies where human beings live like animals. On what they can find, they increase in geometrical progression.
2. In the intermediate stage, Quillard’s principle of population applies. According to this, “Population proportions itself automatically.” In such a society, population increases as food supply increases because population can produce food itself. Here positive checks do not become necessary.
3. In a modern civilised society, Dumont applies his social capillarity principle. In such a society, every individual wants to achieve higher economic and social status. For this, a small family is imperative, because one cannot climb high on the social ladder with the burden of more children on its back.
When an individual earns more income and wealth, his ambition for better position and higher social prestige goes up and consequently the number of children decreases. Therefore, in a civilized society due to social capillarity, fertility goes down. When people migrate to cities from rural or backward areas, their fertility declines.
Thus social capillarity has direct relation with social development, and birth rate and social capillarity are inversely related to each other. The number of children is less when people become more civilized. In the words of Dumont, “Just as a column of liquid must be thin in order to rise under the force of capillarity so must a family be small to rise in the social scale.” According to Dumont, the poor can achieve capillarity if they divert their time, energy and wealth for vertical mobility.
This is possible only when they restrict their families to one or two children. According to him, the birth rate in rural areas is high while it is low in urban areas. The reasons for high birth rate in rural areas are poverty, illiteracy, orthodoxy and lack of vigour.
The reasons for low birth rate in urban areas are people’s ambition for vertical mobility, liberal environment, high standard of living, more income and wealth, capacity of rational thinking, high socio-economic status of women, progressive ideals, high cost of living, the desire of middle class to move into the upper class, etc.
As enough opportunity for social capillarity is not available in a socialist society, Dumont believes that socialism leads to the destruction of social capillarity.
Criticisms:
Dumont’s social capillarity theory has been criticised on the following counts:
1. Nature of Other Factors:
Dumont’s view that low birth rate leads to high position in society is not true because besides birth rate, other factors like social, economic, political, etc. are responsible for moving upward in society.
2. Not a Universal Truth:
It cannot be accepted as a universal truth that one cannot climb high on the social ladder with the burden of more children on one’s back because in reality there are many people with more children who have climbed high and there are many people having less children who are living at the bottom.
If we accept this view of Dumont, the childless couples will be at the top of society. Besides, there are many people in society who have low social status and their standard of living is also low but who have less number of children. Therefore, the number of children or the size of family has not direct relation to the low or high position in the society.
3. Concept not Clear:
Which type of capillarity an individual has to choose as his ideal is not clear in Dumont’s social capillarity concept.
4. Not Applicable to Underdeveloped Societies:
Dumont’s observation that birth rate in rural areas remains high while it is low in cities has also been criticised. It is true that compared to rural areas, birth rate in urban areas is low, but in a country like India, when labourers migrate from rural to urban areas, they come alone and keep their families in rural area. This is one of the reasons for low birth rate in urban areas. So it is not applicable to underdeveloped societies.
5. Not a Complete Theory:
Dumont’s principle is not a complete population theory because social capillarity is one of the motives that can lead to reduction in birth rate.
6. Applicable to Socialist Societies:
Dumont’s assertion that socialism leads to the destruction of social capillarity has been proved wrong. Even in a socialist country like China people are following the social capillarity principle. They want to move higher on the social ladder and are reducing fertility.
7. Karl Marx’s Theory of Surplus Population:
Karl Marx, the famous author of Das Kapital, did not propound any specific theory of population like Malthus. However, he rejected the Malthusian theory as completely imaginary and false. He did not accept Malthus’s view that population increases in geometrical progression and means of subsistence in arithmetical progression. Marx’s views about population growth are based on his theory of surplus value.
According to him, the problem of population arises only in a capitalist society which fails to provide jobs to all workers because the supply of labour is more than its demand. As a result, there is surplus population.
But there is no surplus population in a socialist society where the means of production are in the hands of workers. All able bodied workers are employed and there is no surplus labour. So there is no need to check the growth of population in a socialist country.
Capitalism, according to Marx, is divided into two classes – the workers who sell their ‘labour-power’, and the capitalist who own the ‘means of production’ (factories). Labour-power is like any other commodity. The labourer sells his labour for its value. And its value, like the value of any other commodity is the amount of labour that is required to produce labour-power. In other words, the value of labour-power is the value of the means of subsistence (i.e., food, clothing, housing, etc.) necessary for the maintenance of the labourer.
This is determined by the number of hours necessary for its production. But the value of commodities necessary for the subsistence of the labourer is never equal to the value of the produce that labourer produces. If a labourer works for ten hours a day, but it takes him six hours’ labour to produce goods to cover his subsistence, he will be paid wages equal to 6 hours’ labour. The difference worth 4 hours’ labour goes into the capitalist pocket in the form of profit. Marx calls this unpaid work “surplus value”.
According to Marx, this surplus value leads to capital accumulation. The capitalist’s main aim is to increase the surplus value in order to increase his profit. He does so by “the speeding up of labour”, which means increasing the productivity of labour.
When the productivity of labour increases, the labourer produces the same commodity in less hours, say 4 hours, or he produces more (two) commodities, say in 6 hours. This raises the surplus value and hence the capitalist’s profit.
The increase in the productivity of labour requires a technological change that help in increasing total output and lowering the cost of production. He introduces labour-saving machines which increase labour productivity.
This process of replacing labour by machines creates an industrial reserve army which increases as capitatism develops. The industrial reserve army is the surplus population. The larger the industrial reserve army, the larger the surplus population and the worse are the conditions of the employed labourers.
This is because the capitalists can dismiss dissatisfied and troublesome workers and replace them from the ranks of the reserve army. Capitalists are also able to cut down wages to a semi-starvation level and raise more surplus value, while the surplus population increases.
The Marxian theory of surplus population is explained in Fig. 1 where the labour force is taken on the horizontal axis and the wage rate on the vertical axis. DD is the demand curve for labour and SS is the supply curve of labour. At the wage rate OW, there is increase in the industrial reserve army or surplus population equal to RA (=LL1). As the industrial reserve army expands, the capitalists start adopting labour-saving machines in order to increase the surplus value and hence profits.
Consequently, the supply curve of labour SS starts sliding towards the right and becomes horizontal at S1. The capitalists also start reducing the wage rate simultaneously to the minimum subsistence level OM in order to have more surplus value and profits. Now at this wage rate, the horizontal supply curve MS1 equals the demand curve for labour at point E1. Thus at the subsistence wage rate OM the entire working population OL1 becomes the surplus population.
Marx explains his surplus theory of population thus:
“It is the working population which, while effecting the accumulation of capital also produces the means whereby it is itself rendered relatively superfluous, is turned into a relatively surplus population, and it does so to an ever increasing extent. This is a law of population peculiar to the capitalist method.”
Criticisms:
Marx’s theory of surplus population has been criticised on the following grounds:
(1) Unrealistic Theory:
The Marxian theory is unrealistic because it is based on the theory of surplus value. The concept of surplus value has not been accepted even in socialist countries since it is unrealistic. Therefore, the very basis of his population theory does not exist.
(2) Not Applicable to Socialist Countries:
Marx’s contention that there is no population problem in a socialist country has been proved wrong. China, the largest socialist country of the world, has been faced with the problem of population growth. It has been trying to control it by adopting “one-child” norm.
(3) Technological Progress reduces Industrial Reserve Army:
According to Marx, with increasing technical progress the industrial reserve army expands which, in turn, leads to surplus population. This is an exaggerated view because the long run effect of technical progress is to provide more employment.
(4) No Explanation of Determinants:
Marx does not explain the determinants of population growth like birth rate, death rate, migration, etc.
Thus Marx’s explanation of population growth is not a theory in the true sense but simply a view.
8. Leibenstein’s Motivational Theory of Population Growth:
Leibenstein’s theory of population growth forms part of his Critical Minimum Effort Thesis on economic development. It is based on his empirical evidence that the rate of population growth is a function of the level of per capita income which, in turn, depends on the stage of economic development.
Leibenstein’s view is based on Dumont’s “Social-capillarity Thesis” which states that with the increase in per capita income, the desire to have more children as productive agents declines.
This means that as per capita income rises with economic development, the fertility rate declines. Similarly, the mortality rate also declines, as there is improvement in public health measures with economic development. But the decline in the mortality rate is fast as compared to the decline in the fertility rate. This creates a “fertility gap” which continues to widen for quite some time.
Leibenstein explains the fertility gap in terms of the cost-benefit analysis of bringing up an additional child. There are three types of benefits or utilities which parents derive from an additional child.
They are:
(a) consumption utility which they get out of love and pleasure by rearing a child;
(b) productive utility when the child starts earning from childhood and is a source of income for his parents; and
(c) old age security utility which the child possesses when he supports his parents in old age who are unable to earn.
The costs of bringing up an additional child are of two types – direct and indirect. The direct costs relate to expenditure on feeding, clothing, education, etc. These expenses are incurred by parents till the child starts earning and become self-supporting.
The indirect costs relate to the opportunities foregone by parents when an additional child is born. Such opportunities foregone are earnings lost by the mother during and after the pregnancy, less social and spatial mobility of parents due to additional responsibility in bringing up the additional child, etc.
Lack of spatial mobility means potential loss of income. On the whole, the cost of bringing up an additional child is less to parents with low per capita income and high with high per capita income.
There are three types of effects which influence the utilities and costs of bringing up an additional child during the process of economic development. They are the income, survival and occupational distribution effects. With economic development, as per capita income increases, the chances of survival increase and there are changes in the occupational distribution.
Leibenstein explains these three effects in relation to the utilities and costs during the process of economic development. We first explain the per capita income effect in Fig. 2.
Per capita income of the family is shown on the horizontal axis while utilities and costs per child are taken on the vertical axis. The consumption utility curve is assumed as constant because it is independent of the family per capita income. It is the pleasure and satisfaction that the parents get in rearing a child which has nothing to do with their per capita income. This is shown by the horizontal curve C in the figure.
The curves S and P depict security utility and productive utility respectively which decline as the per capita income increases. As the per capita income increases, parents become wealthier to provide for their own security and depend less on the child in old age.
Similarly, as the per capita income increases, there is no need for the child in the family to earn during childhood in order to support the family. Schooling is extended and the child is less valuable as a productive agent. Thus the P curve also slopes downward as per capita income increases.
The direct and indirect costs of bringing up an additional child increase in proportion to the rise in per capita income of the family. This is shown by the 45° straight line curve through the origin.
So far as the survival effect is concerned, the increased survival rates raise the three utility curves. The reason is that when an additional child is expected to survive for long years of life, there are more expected years of satisfaction for the parents. But the survival effect reduces the motivation to have an additional child on the part of parents.
Lastly, the occupational distribution effect adds to the direct and indirect costs of an additional child. As per capita income increases, economic and social mobility increases. There is spread of urbanisation and specialisation which lead to the expansion of job opportunities. Parents are required to provide professional and costly education to the children. This prohibits parents to have an additional child.
Leibenstein’s motivational theory, as explained above, is closely related to the different stages of economic development. To start with, at the subsistence equilibrium level of income, fertility and mortality rates are the maximum consistent with the survival rate of population. If the per capita income is raised above the subsistence equilibrium position, the mortality rate falls without any drop in the fertility rate. The result is an increase in the growth rate of population.
Thus, an increase in per capita income tends to raise the growth rate of population. But it is only up to a point. Beyond that the increase in the per capita income lowers the fertility rate and as development gains momentum, the rate of population growth declines. This is because with the increase in per capita income, the desire to have more children to supplement parental incomes, declines.
Increased specialization following rising income levels and the consequent social and economic mobility make it a difficult and costly affair to rear a large family. Therefore, the growth rate of population becomes constant and then starts declining gradually as the economy advances towards the path of sustained development, as has happened in the case of Japan and Western countries.
There is, according to Leibenstein, a biologically determined maximum growth rate of population between 3 and 4 per cent. In order to overcome this population hump, there should be a larger increase in per capita income. This is discussed with the help of Fig. 3 where the rate of population growth or national income growth is measured along the horizontal axis and level of per capita income on the vertical axis.
The curve N measures the level of per capita income which generates a level of national income growth equal to the growth rate of population. The curve P indicates the rate of population growth at each level of per capita income. Starting from point a which represents the subsistence equilibrium point where there is absence of population and income growth, if the per capita income is raised to Oyb, the population growth rate is 1 per cent, while the income growth rate is less than 1 per cent. At the Oyc level of per capita income, the rate of population growth is higher than the rate of national income growth, i.e., ycg>ycc, the former is 2 per cent while the latter is 1 per cent.
Therefore, the per capita income level should be so raised as to increase the national income by more than the rate of population growth. This is only possible after Oye level of per capita income whence the rate of population growth starts declining. Point e is the 3 per cent maximum biologically determined growth rate of population assumed by Leibenstein. Oye is thus the critical minimum per capita income level which can sustain itself and generate the process of sustained economic development.
Its Criticisms:
Leibenstein’s theory has the following weaknesses:
(1) Population Growth Rate Related to Death Rate:
The theory is based on the assumption that the rate of growth of population is an increasing function of the level of per capita income up to a point, but beyond that it is a decreasing function of the latter. But the first process is related to the decline in the mortality rates due to the advancements in medical science, and improvements in public health measures in underdeveloped countries, and not to an increase in the level of per capita income.
In India, there has been a decline in crude death rate from 24 per thousand in 1960 to 8 in 2001, not due to a rise in the per capita income which is almost stationary but as a result of the above mentioned factors.
(2) Decline in Birth Rate not due to Increase in Per Capita Income:
Similarly, the decline in the birth rate cannot be attributed to an increase in the per capita income at the critical minimum level which surpasses the growth rate of population, as is supposed by Leibenstein. His conclusions are based on the experience of advanced Western countries and Japan.
But in underdeveloped countries the problem of declining birth rate is mostly socio-cultural in nature. What is required is change in ‘the attitude, understanding, education, social institutions and even certain intellectual perceptions.’ Rise in per capita income alone cannot perform the trick.
There is no guarantee that with the decline in the birth rate, population would start decreasing as per capita income increases in underdeveloped countries.
(3) Ignores State Efforts to Reduce Birth Rate:
Leibenstein ignores the state action in bringing down the fertility rate. As the experience of japan has shown, no underdeveloped country can afford to wait for the per capita income to rise above the critical minimum level so that the birth rate may start declining automatically.
In such a situation, she may reach the stage of the population explosion thereby creating more problems than she can solve by the rise in the per capita income.
Conclusion:
Thus Leibenstein’s motivational theory states that at the low level of per capita income, there is a greater motivational force on the part of parents to have an additional child as a productive agent and a source of security. This motivation continues upto a particular level of per capita income.
But as per capita income increases beyond that level, the motive to have an additional child declines because the direct and indirect costs of bringing up an extra child increase while productive and security utilities decline. These sequences are closely related to the different stages of economic development.