Which of the following statements best describes the content of the theory of distribution ?

Correct — D, (d) The distribution of income between the owners of factor resources.

In economics the THEORY OF DISTRIBUTION has a settled and narrow meaning. It is the branch of price theory that explains how the national product is divided among the FACTORS OF PRODUCTION, and therefore among the people who own them. Its subject is the pricing of factor services:

land earns RENT, labour earns WAGES, capital earns INTEREST, the entrepreneur earns PROFIT.

This is called the FUNCTIONAL distribution of income, because income is traced to the FUNCTION performed in production rather than to the person who receives it. The questions it asks are: what determines the wage rate ? what determines the rate of interest ? why does a piece of land command a rent at all ? And its central proposition, the marginal productivity theory, is that in a competitive market each factor tends to be paid the value of its marginal product — the addition to revenue made by employing one more unit of it.

That is exactly what option (d) says. 'Owners of factor resources' are the landlords, workers, lenders and entrepreneurs who supply the factors, and the theory explains how the product is divided among them.

The distinction the question is really testing is between FUNCTIONAL and PERSONAL distribution. Personal or SIZE distribution asks how income is spread across individuals or households — how much goes to the poorest tenth, how much to the richest — and it is measured by the Lorenz curve and the Gini coefficient. The two are related but they are not the same enquiry, and only one of them is what economists call the theory of distribution. A single person may own several factors, and the same functional shares can produce very different personal distributions depending on who owns what.

Notice how the option set is built. Option (a) gives the personal distribution; option (b) gives the fiscal question of sharing revenues between levels of government; option (c) gives the normative question of what a just distribution would be. Each is a genuine subject with a real literature, and each is a different subject from the one asked about.

Why the others are wrong

• (a)The distribution of income among different individuals in the economy — This describes the PERSONAL or SIZE distribution of income, which is a real and important subject but not what 'the theory of distribution' names. Personal distribution asks how total income is spread across households — the share of the bottom decile, the share of the top one per cent — and is studied through the Lorenz curve, the Gini coefficient and the Kuznets hypothesis. Functional distribution asks a prior question: what determines the RATE at which each factor is paid. The two are connected only through the pattern of factor ownership, since an individual's income is the sum of the returns to whatever factors that individual happens to own. This is the most defensible wrong option and the one the item is designed around.
• (b)The distribution of income between the Centre and the State Governments — This is FISCAL FEDERALISM, not distribution theory. It concerns the sharing of tax revenues between levels of government and is governed in India by Article 280, under which the Finance Commission recommends the distribution of the net proceeds of taxes between the Union and the States and the principles governing grants-in-aid. The word 'distribution' is genuinely used in both contexts, which is why the option is on the page, but the two enquiries have nothing in common: one is about factor prices in markets, the other about transfers between governments. This paper asks about the second in its own right a few questions later. 'Centre' and 'State Governments' are capitalised as the booklet sets them.
• (c)The principle of just distribution of wealth and income — This is a NORMATIVE question — what distribution OUGHT to obtain — and belongs to welfare economics and to political philosophy. The theory of distribution is POSITIVE: it explains how factor prices are actually determined by the interaction of demand and supply in factor markets, and it makes no claim that the resulting shares are fair. The confusion is a common one because the marginal productivity theory has sometimes been pressed into service as a justification of the shares it explains, but explaining an outcome and endorsing it are different operations. Note also that the option speaks of WEALTH as well as income; distribution theory is about flows of factor income, not about the stock of assets.

Distribution theory is the second half of microeconomics. The first half, the theory of value, explains the prices of GOODS; the second explains the prices of FACTORS. Both work through demand and supply, but factor markets have two features of their own.

FACTOR DEMAND IS DERIVED. Nobody wants a machine or an hour of labour for its own sake; it is wanted for what it can help produce. So the demand for a factor comes from the demand for the final product, which is why a fall in the demand for a good becomes a fall in the demand for the workers who make it.

THE MARGINAL PRODUCTIVITY PRINCIPLE. A profit-maximising firm hires a factor up to the point where the value of its marginal product equals its price. In competitive equilibrium each factor is therefore paid the value of what the last unit of it contributes. A related result, product exhaustion, holds that under constant returns to scale paying every factor its marginal product exactly uses up the whole product with nothing left over.

THE FOUR SHARES, each with its own body of theory: RENT — Ricardo's theory treats rent as a differential surplus arising from differences in fertility or situation, and the modern concept of economic rent generalises it to any payment above transfer earnings. WAGES — the subsistence theory, the wages fund theory, marginal productivity, and bargaining theories that allow for trade unions and for the fact that labour markets are not auction markets. INTEREST — the time preference and abstinence theories, the loanable funds theory, and Keynes's liquidity preference theory. PROFIT — Knight's theory of profit as the reward for bearing uninsurable uncertainty, Schumpeter's theory of profit as the return to innovation, and risk-bearing and monopoly theories.

The accounting counterpart is worth holding alongside: national income measured as the sum of factor incomes must equal national income measured as expenditure on final goods. Distribution theory explains how the first of those totals is divided; national income accounting merely records the division.

Key facts

• The theory of distribution is the branch of price theory explaining how national product is divided among the factors of production and hence among their owners.
• It is the FUNCTIONAL distribution — rent to land, wages to labour, interest to capital, profit to the entrepreneur — as against the PERSONAL or size distribution across individuals.
• Personal distribution is measured by the Lorenz curve and the Gini coefficient; functional distribution is explained by factor pricing.
• The marginal productivity theory holds that in competitive equilibrium each factor is paid the value of its marginal product.
• Product exhaustion: under constant returns to scale, paying every factor its marginal product exactly exhausts the product.
• Ricardo explained rent as a differential surplus; Knight explained profit as the reward for bearing uninsurable uncertainty; Schumpeter explained it as the return to innovation.
• Distribution theory is positive, explaining how factor shares are determined; the question of what shares would be JUST belongs to welfare economics.
• The distribution of tax revenues between the Union and the States is fiscal federalism, governed in India by Article 280 and the Finance Commission — a different use of the word.

Common traps

• Reading 'distribution' in its everyday sense of inequality between individuals. That is the personal distribution, printed as option (a).
• Choosing the option about just distribution. The theory is positive and explains how factor shares arise; it does not prescribe what they ought to be.
• Being drawn to the Centre-State option because the word 'distribution' is used there too. That is fiscal federalism under Article 280.
• Forgetting that the theory covers rent, interest and profit as well as wages. It is about all four factor incomes, not only about labour.

• practice — not a real PYQ

  The Lorenz curve and the Gini coefficient are used to measure

  • (a)the functional distribution of income among factors of production
  • (b)the personal distribution of income among households
  • (c)the rate of growth of national income
  • (d)the distribution of tax revenue between the Union and the States

  Answer(b) the personal distribution of income among households — both are measures of inequality in the size distribution of income across people. The functional distribution among factors of production is a different enquiry, explained by factor pricing rather than measured by an inequality index.

• practice — not a real PYQ

  According to the marginal productivity theory of distribution, in a competitive market a factor of production tends to be paid

  • (a)its average product
  • (b)the value of its marginal product
  • (c)a share fixed by custom and bargaining
  • (d)the total product divided equally among all factors

  Answer(b) the value of its marginal product — a profit-maximising firm employs a factor up to the point where the addition to revenue from the last unit equals what that unit costs. Under constant returns to scale, paying every factor on this principle exactly exhausts the product.