Explain the concept of Malthusian theory of population?

Malthusian theory of Glut or over population:

Malthus developed the theory of glut or over production on the basis of capitalist system. He pointed out that in a capitalist economy effective demand can never be sufficient to clear the supply. His basic argument was that without exogenous spending by unproductive consumers the process of capitalist accumulation would lead to stagnation. 

He said that when saving was increased for the purpose of capital accumulation, effective demand would go down to that extent. Therefore for due to consumption, Glut or over production problem arises in the economy.

Malthusian theory of glut can be explain with the help of following figure-

In the above figure on OX axis we measure labour employment and OY axis we measure output level. 45 degree line denotes effective demand ED. AC is actual consumption line. WC is warranted consumption line and total output of the economy is OG=NP. The demand in the economy is given by the actual consumption line NM. But the warranted or justified consumption level is NP. Hence there arises the stock of unsold good or glut. It can be measured as-

Glut=Warranted consumption - Actual consumption

       =NP-NM

       =PM

Thus under consumption in the capitalist system is responsible for glut or (over production).

Criticism of Malthusian theory of Glut or over population:

(i) Malthusian theory is not empirically true. Because he didn't explain certain important determinants of effective demand.

(ii) This theory is one sided because here more importance has been given on effective demand but not on the aggregate demand and aggregate supply.

(iii) In the context of international trade, the over production of the capitalist economy can be used by the way of international trade.

(iv) Malthus didn't provide any clear idea about the causes of decline of aggregate consumption expenditure.

Malthusian theory of Population:

In 1798, Malthus has discussed his theory of population in his book "An Essay on the Principle of population" but he has briefly elaborated this theory in 1803 in his second edition of his book. The Malthusian theory of population is the theory of an exponential population growth and  the arithmetic food supply growth. He believed that through preventive checks and positive checks, the population would be controlled to balance the food supply with the population level.

Malthus states that population increases in a geometric ratio like at the rate of 1,2,4,8,16,32, etc. and food supply increases only in an arithmetic ratio like at the rate of 1,2,3,4,5,6,7,8,9,10 etc.  He believes that the population of a country would double itself in every 25 years if it is not checked. Therefore, it will be better to impose check on population rather than to increase the subsistence.

This can be done by the application of some checks by nature or by man himself or by both.

Malthus has considered two main assumptions while presenting his principle of population which are-

(i) The food is necessary for the existence of men.

(ii) The passion between saxes is natural and will remain nearly in it's present state.

The Malthusian theory of population can be explain with the help of a following diagram-

The food supply in arithmetical progression is measured on the horizontal axis and the population in geometrical progression on the vertical axis. The curve M is the Malthusian population curve which shows the relation between population growth and measure in food supply. It rises upward swiftly . 

There is a imbalance between increasing population and supply of food. In the diagram it is observed that when the food supply is 4, the population is 8 and hence such sort of imbalance raises the population curves upwards.

To control over- population resulting from the imbalance between population and food supply, Malthus suggest preventive checks and positive checks. The preventive checks are applied by a man to control the birth rate (population). They are foresight, late marriage, moral restraint, etc. The Positive checks operate in the form of vice, misery, war, floods and other natural climates which tend to reduce the population and thereby bring a balance with the food supply.

Criticism Malthusian theory of Population:

The Malthusian theory of population has severely been criticised on the following grounds-

(i) Population is not double after every 25 years if it is not check is a wrong concept because it is not historically proved.

(ii) In the presence of technical innovation, the food supply is not arithmetically increase.

(iii) Malthus perhaps ignores the presence of international trade during that time.

(iv) Malthus assumes increase birth rate is case of increasing population. But he ignored falling death rate is also a reason for population growth.

(v) This theory is considered as wrong because of failure to difference between the desire of sex and the desire of children.