The Modern Theory of Rent 1 Demand & Supply Theory of Rent:
The classical economists thought that land as a factor of production was different from other factors of production. But modern economists thought that all the factors of production are alike and there is no basic difference between them. Hence, a special theory of rent, developed by Ricardo is not necessary. Therefore, economists like Joan Robinson and Boulding have contributed their, ideas for the determination of rent, which is known as the "Modern Theory of Rent".
"The essence of the conception of rent is the conception of surplus earned by a particular part of a factor of production over and above the minimum earnings that is necessary to induce it to do work" - Joan Robinson Rent is the difference between the actual earnings of a factor of production and its transfer earning.
Rent = Actual earning - Transfer earning.
The minimum payment that has to be made to a particular factor of production to retain it in its present use is known as transfer earnings.

Introduction:
In his book "The general theory of employment, interest and money" in 1936, Keynes propounded the liquidity preference theory of Interest.
Theory:
Interest is the reward for parting with liquidity for a specified period of time.
Meaning:
Liquidity preference means the preference of people to hold wealth in the form of liquid cash and not in non-liquid assets like bonds, securities, bills of exchange, land, building, gold.
Motives:
Transaction motive:
It relates to the desire of the people to hold cash for the current transaction. M_t = f(y)
Precautionary motive:
It relates the desire of the people to hold cash to meet unexpected expenditures such as sickness, accidents, fire. M_P = f(y)
Both these motives depend on the income level.
Speculative motive:
It relates to the desire of people to hold cash in order to take advantage of market movements regarding the future changes in the price of bonds
There is inverse relation between liquidity preference and interest rate. M_s = f(i)
Determination of interest rate:

(i) The rate of interest is determined by the demand for and the supply of money.
(ii) The demand for money is liquidity preference for speculative motive.
(iii) The supply of money is determined by the policies of the government and the central bank.
(iv) The supply of money consists of coins, currency notes and bank deposits.
Equilibrium:
(i) In the short run supply of money is constant.
(ii) LP is liquidity preference curve M₂ M₂ is supply curve of money.
(iii) Both curves interest at E, which is the equilibrium point.
(iv) If LP increases from LP to L₁P₁ & money supply being constant, the interest rate increases from OI to OI₁. (fig a)
(v) Suppose LP is constant (fig b).
(vi) If supply of money is OM₂, the interest is OI₂ & if the supply of money is reduced from OM₂ to OM₃, the interest would increase from OI₂ to OI₃. If money supply increases, interest rate decreases.
Criticism:
(i) This theory does not explain the existence of different interest rates prevailing in the market at the same time.
(ii) It explains interest rate in the short-run.
Conclusion:
The Keynesian liquidity preference theory is an improvement over other theories.

Introduction:
The loanable funds theory also called Neo-classical theory was developed by Swedish economists Wicksell, Bertil Ohlin, Viner, Gunnar Myrdal and others.
Theory:
Interest is the price paid for the use of loanable funds.
Demand for loanable funds:
Investment:
Business firms borrow money for buying capital goods.
Consumption:
Individuals borrow money for consumption.
Hoarding:
People hoard money because of people's preference for liquidity, idle cash balance. The demand for C, I and H varies inversely with rate of interest.
Supply of loanable funds:
(i) Savings is of 2 types savings planned by individuals are called ex-ante savings. (eg) LIC premium, EMI payment.
(ii) Unplanned savings is ex-post savings. It is saving left out after spending.
(iii) Bank credit commercial banks create credit and supply loanable funds to investors.
(iv) Dishoarding means bringing out the hoarded money into use. After 1991, public sector undertakings are being sold to private to mobilize funds.
(v) Disinvestment means not providing sufficient funds for depreciation of equipment.
(vi) The supply of loanable funds of S, BC, DH, DI vary directly with interest rate.
Equilibrium:
The rate of interest is determined by the equilibrium between the total demand for and the total supply of loanable funds.
Diagram Explanation:

x axis demand for and supply of loanable funds.
y axis rate of interest.
LS curve- total supply of loanable funds.
(S + BC + DH + DI)
LD curve - total demand for loanable funds
(I + C + H)
LD & LS curves intersect at E. OR = rate of interest OM = amount of loanable funds.
Criticism:
(i) Asymmetric information & moral hazard have not been included.
(ii) Some large firms due to their political powers get huge bank credit at lower interest rate.
(iii) But due to non-performing assets (NPAs) small firms & depositors lose their interest income.
(iv) The loanable funds theory is indeterminate unless the income level is already known.
(v) It is difficult to combine real factors like savings & investment with monetary factors like bank credit & liquidity preference
Conclusion:
Loanable fund theory is wider in scope compared to classical theory.

Introduction:
The classical theory of rent is called Ricardian Theory of rent.
Definition:
(i) According to David Ricardo "Rent is that portion of the produce of the earth which is paid to the landlord for the use of the original and indestructible powers of the soil".
Assumptions:
(i) Land differs in fertility and has original & indestructible powers.
(ii) Rent depends on fertility and location of land.
(iii) There is perfect competition and is applicable in long run.
(iv) Land is used for cultivation only and there is marginal land or no-rent land.
(v) Most fertile lands are cultivated first.
Illustration:
1. Assume a group of people go to a newly discovered island and settle down there.
2. They will first cultivate the most fertile land 'A'.
3. Since land is abundant & idle they need not pay rent.
4. Given labour and capital yield per acre on 'A' grade land is 40 bags of paddy.
5. Suppose another group of people settle down in the same island. The demand for agricultural produce increases.
6. Because of the law of diminishing returns A grade land alone cannot produce all the food needed.
7. So less fertile land B is cultivated.
8. For the same amount of labour and capital only 30 bags of paddy are produced.
9. The surplus of 10 bags per acre on 'A' grade land is the economic rent of 'A' grade land.
10. If yet another group of people goes and settles down in the same island, the least fertile 'C' grade land will be cultivated.
11. For the same amount of labour and capital the yield per acre is 20 bags of paddy.
12. The surplus of 20 bags for 'A' grade land and 10 bags for 'B' grade land is their economic rent.
13. The cost of production of 'C' grade land is just equal to the price of its produce and so there is no rent.
14. 'C' grade land is 'no rent land' or 'marginal land'.
15. Land which yields rent is intra marginal land.
16. Rent is the differential advantage of the superior land over the marginal land.
Grades of Lands Production Rent  A 40 40-20=20 B 30 30-20=10 C 20 20-20=0
Diagram Explanation:
X axis- grades of land.
Y axis-yield per acre.
OA, AB, BC are grade A, B, C lands.
(i) The use of equal amount of labour and capital on each of them gives yield 40, 30 & 20.
(ii) The economic rent yielded by A & B grade land is the shaded area.
(iii) They are intra marginal lands.
(iv) 'C' grade land is no rent land.
Criticism:
(i) The order of cultivation from most fertile to least is historically wrong.
(ii) In reality rent enters into price.
Conclusion:
(i) Thus Ricardo explains how rent arises on land.

Introduction:
(i) Marginal productivity theory of distribution was developed by Clark, Wicksteed and Walras.
(ii) This theory explains how the prices of various factors of production are determined.
Assumptions
(i) All the factors of production are homogeneous, can be substituted for each other and are perfectly mobile.
(ii) There is perfect competition in the factor & product market.
(iii) There is full employment with no technological change.
(iv) The theory is applicable only in long run.
(vi) The entrepreneurs aim at profit maximisation.
(vii) There is no government intervention in fixing the price of a factor.
Explanation:
(i) The reward for any factor of production is equal to the marginal productivity of that factor.
(ii) The greater the productivity of a factor higher will be its reward.
(iii) The price of a factor of production depends upon its productivity.
(vi) The price will be equal to marginal revenue product of that factor.
(v) Under certain conditions, the price of a factor will be equal to both the average and marginal products of that factor.
Marginal productivity under perfect competition:

(i) fig (a) x axis represents factor units.
(ii) y axis shows factor price & revenue.
MRP = Marginal revenue product curve.
ARP = Average revenue product curve.
AFC = Average factor cost curve.
MFC = Marginal factor cost curve.
(iii) AFC is horizontal & MFC coincides with it.
(iv) The firm is in equilibrium (maximum profit) when MFC = MRP at Q by employing ON units of factors & paying (OP price or NQ) where MFC = MRP = ARP.
(v) The price paid to the factor NQ is equal to MRP (NQ) and ARP (NQ) beyond Q no employer will employ factors because after that point, the price paid to the factor is more than MRP and ARP.
Marginal productivity under Imperfect competition:

(i) fig(b) AFC represents the price paid to the factors. It increases as the number of factors demanded by the employer increases.
(ii) As AFC rises, MFC lies above AFC. It represents the MC paid to the factors.
(iii) At the point Q, MFC = MRP, where the employer attains his maximum profit and so he stops employment of the factors at the point.
(iv) But the AC paid is NRSO and AR is NQ or OP
(v) Total revenue is NQPO.
(vi) Exploitation per unit of factor is RQQ
(vii) But the total number of factors is ON. Thus the total exploitation of factor by the employer is RQ XSR = PQRS (shaded area).
Criticisms:
(i) Factors of production are not homogeneous.
(ii) They cannot be substituted for each other.
(iii) It cannot be applied in the short run.
Conclusion:
This theory is also called "General Theory of Distribution" or "National Dividend Theory of distribution".