1 Economic Concepts · 1.1 Microeconomics: demand, production, markets and factor pricing
1.1.6 Factor pricing: rent, wages, theories of interest and profit
Land, labour, capital and enterprise earn rent, wages, interest and profit; the general rule is that a firm pays a factor up to the value of its marginal product, and special theories explain each reward.
- APPSC Paper I
- Advanced level
- 12 min read
- Free
Core facts
- Factors and rewards: land → rent; labour → wages; capital → interest; entrepreneur (organisation) → profit.
- Marginal productivity theory (J.B. Clark; also Wicksteed and Walras): a factor's price equals its marginal productivity.
- MRP (marginal revenue product) = MP × MR. VMP (value of marginal product) = MP × P. Under perfect competition in the product market, MR = P, so MRP = VMP.
- A firm hires a factor until factor price = MRP. The falling MRP curve is the firm's demand curve for the factor.
- Product exhaustion theorem (Wicksteed; uses Euler's theorem): under constant returns to scale, paying every factor its marginal product exactly uses up the total product.
- Ricardian rent (1817): payment for the use of the "original and indestructible powers of the soil"; it is a differential surplus of better land over marginal (no-rent) land.
- Ricardo: rent is price-determined, not price-determining. Rent arises on both the extensive margin (lands of different fertility) and the intensive margin (more doses on the same land).
- Modern theory of rent: economic rent = actual earnings − transfer earnings. Transfer earnings = minimum payment needed to keep a factor in its present use. Any factor can earn rent.
- Quasi-rent (Alfred Marshall): short-run surplus of man-made equipment = TR − TVC.
- Real wage = money wage adjusted for prices: what the wage can buy.
- Wage theories: subsistence theory (Ricardo; the "iron law of wages", Lassalle), wages fund theory (J.S. Mill; he withdrew it in 1869), residual claimant theory (F.A. Walker), marginal productivity theory, modern demand-and-supply theory.
- Backward-bending supply curve of labour: beyond a high wage, the income effect outweighs the substitution effect, so workers choose more leisure.
- Interest theories: classical (saving = investment; a real theory), abstinence (Nassau Senior), waiting (Marshall), agio / time preference (Böhm-Bawerk), impatience (Irving Fisher), loanable funds (Wicksell, Robertson, Ohlin; neoclassical), liquidity preference (Keynes, 1936; a monetary theory).
- Keynes: interest is the reward for parting with liquidity. Three motives for holding money: transactions, precautionary, speculative.
- Liquidity trap: at a very low interest rate, demand for money becomes perfectly elastic; more money does not lower the rate.
- Profit theories: dynamic theory (J.B. Clark), innovation theory (Schumpeter, 1911), risk-bearing theory (F.B. Hawley, 1907), uncertainty-bearing theory (Frank Knight, 1921), rent theory of profit (F.A. Walker).
Explained
1. How much labour does a firm hire?
Example 1. Output sells at ₹5 a unit (perfect competition). The daily wage is ₹60. Marginal products of successive workers are 20, 16, 12, 8 and 4 units. How many workers are hired?
| Worker | MP | VMP = MP × 5 | Hire at ₹60? |
|---|---|---|---|
| 1st | 20 | 100 | Yes |
| 2nd | 16 | 80 | Yes |
| 3rd | 12 | 60 | Yes (VMP = wage) |
| 4th | 8 | 40 | No |
Solution. Hire while VMP ≥ wage. Answer: 3 workers. Output = 20 + 16 + 12 = 48 units, revenue ₹240, wage bill ₹180.
2. Ricardian rent.
Example 2. Three grades of land, A, B and C, each get the same labour and capital costing ₹2,000 and produce 40, 30 and 20 quintals. Grade C is the marginal land (no rent). Find the rent of A and B in quintals. Solution. Rent = produce − produce of marginal land. A: 40 − 20 = 20; B: 30 − 20 = 10; C: 0. Answer: A 20 quintals, B 10 quintals, C nil. If population growth brings a poorer grade D (15 quintals) into cultivation, D becomes the no-rent land and rents rise to A 25, B 15, C 5.
- Ricardo's assumptions: land has one use (corn), lands differ in fertility or location, the law of diminishing returns applies, and cultivation spreads from better to worse land.
- Corn is not high because rent is paid; rent is paid because corn is high (price-determined).
3. Modern theory: economic rent and transfer earnings.
Example 3. An engineer earns ₹50,000 a month in her present job. Her best alternative job pays ₹35,000. Find her economic rent. Solution. 50,000 − 35,000. Answer: ₹15,000 (₹35,000 is her transfer earnings).
- Perfectly inelastic supply (e.g. land for the economy as a whole): the whole earning is economic rent.
- Perfectly elastic supply: the whole earning is transfer earnings; economic rent is zero.
- Normal upward-sloping supply: part rent, part transfer earnings.
4. Quasi-rent.
Example 4. A firm's machine-based output yields TR = ₹1,00,000. TVC = ₹70,000 and TFC = ₹20,000. Find quasi-rent and net profit. Solution. Quasi-rent = TR − TVC = ₹30,000. Net (supernormal) profit = quasi-rent − TFC = ₹10,000. Answer: quasi-rent ₹30,000; profit ₹10,000.
- Quasi-rent is temporary: in the long run new machines are built and it disappears.
5. Money wage and real wage.
Example 5. A worker's daily money wage rises from ₹500 to ₹600 while the price index rises from 100 to 120. Find the real wage now. Solution. 600 × 100/120. Answer: ₹500 at base prices, so the real wage has not changed.
- Real wage depends on money wage, prices, fringe benefits (housing, medical), regularity of work, and the nature and future prospects of the job.
6. Theories of interest in short.
| Theory | Who | Interest set by |
|---|---|---|
| Classical | Marshall, Pigou | Saving = investment |
| Loanable funds | Wicksell, Robertson, Ohlin | Demand = supply of loanable funds |
| Liquidity preference | Keynes (1936) | Demand for money = money supply |
| Time preference | Böhm-Bawerk, Fisher | Preference for present goods |
- Loanable funds supply = saving + new bank credit + dishoarding + disinvestment. Demand = investment + hoarding + borrowing for consumption.
- Keynes: transactions and precautionary demand depend on income; speculative demand depends inversely on the interest rate.
7. Theories of profit in short.
- Clark's dynamic theory: in a static economy there is no profit; profit arises from five dynamic changes: population, capital, methods of production, forms of business organisation, and consumers' wants.
- Schumpeter's innovation theory: profit is the reward for innovation (new product, new method, new market, new source of raw material, new organisation of an industry); it vanishes when others imitate.
- Hawley's risk theory: profit is the reward for bearing risk.
- Knight's uncertainty theory: insurable risks (fire, theft) are costs, not a source of profit; profit rewards bearing non-insurable uncertainty (changes in demand, competition, policy).
Deeper
1. Marginal productivity theory: limits. It assumes perfect competition, homogeneous units of a factor, full employment and measurable marginal products. It explains the demand side only; the price also needs supply. Under monopsony a firm pays a wage below MRP; Pigou and Joan Robinson called this exploitation of labour. Trade unions and minimum wages can raise wages and, under monopsony, even employment.
2. Demand for a factor is derived demand. It depends on the demand for the goods it helps produce. It is more elastic when (Marshall's rules): the product's demand is elastic, the factor is easy to substitute, the factor's share in total cost is large, and the supply of other factors is elastic.
3. Euler's theorem. For a production function with constant returns to scale, Q = L·MPL + K·MPK. Example: Q = L^0.5 K^0.5 at L = 4, K = 9: Q = 2 × 3 = 6; MPL = 0.5 × 3/2 = 0.75, MPK = 0.5 × 2/3 = 1/3; L·MPL + K·MPK = 3 + 3 = 6 = Q. ✓
4. Liquidity preference: criticisms. Hicks and Hansen argued the theory is indeterminate: the money demand curve depends on income, and income depends on the interest rate through investment. The IS-LM model (Hicks, 1937) fixes income and the interest rate together. The loanable funds theory is criticised for the same circularity.
5. Nominal and real interest (Fisher equation). Nominal rate ≈ real rate + expected inflation; exactly (1 + nominal) = (1 + real)(1 + inflation).
Example 6. A deposit pays 10% while inflation is 6%. Find the real rate. Solution. Approximate: 10 − 6 = 4%. Exact: 1.10 ÷ 1.06 − 1 = 0.0377. Answer: about 3.77% (≈ 4% by the short rule).
6. Gross and net. Gross interest = net (pure) interest + reward for risk + payment for management of the loan + inconvenience. Gross profit (accounting) includes implicit rent, wages and interest on the owner's own factors; net (pure) profit is the reward for enterprise alone. Profit is a residual and can be negative; the other rewards are contractual.
7. Modern theory of rent applied to people. A film star's or cricketer's high pay is mostly economic rent, because their transfer earnings (next best job) are far lower. A tax on pure economic rent does not reduce the factor's supply, an idea used by Henry George (single tax on land).
8. Scarcity rent vs differential rent. Scarcity rent arises when land is limited as a whole even if all land is equally fertile; differential rent (Ricardo) arises from differences in fertility or location.
Common traps
- ✗ "Rent determines the price of corn (Ricardo)." ✓ Rent is price-determined, not price-determining.
- ✗ "Only land earns economic rent." ✓ In the modern theory any factor can earn economic rent (earnings above transfer earnings).
- ✗ "Quasi-rent is earned by land." ✓ Quasi-rent (Marshall) is the short-run surplus of man-made equipment: TR − TVC.
- ✗ "Liquidity preference was given by Marshall." ✓ Keynes (1936); classical theory is linked to Marshall and Pigou.
- ✗ "Loanable funds theory was given by Keynes." ✓ It is the neoclassical theory of Wicksell, Robertson and Ohlin.
- ✗ "Innovation theory of profit: Frank Knight." ✓ Innovation = Schumpeter; uncertainty = Knight; risk = Hawley; dynamic = J.B. Clark.
- ✗ "Knight said profit rewards insurable risks." ✓ Profit rewards non-insurable uncertainty; insurable risks are a cost.
- ✗ "Wages fund theory: Ricardo." ✓ Wages fund = J.S. Mill; subsistence (iron law) = Ricardo / Lassalle; residual claimant = Walker.
- ✗ "VMP = MP × MR." ✓ VMP = MP × P; MRP = MP × MR.
Quick revision
- Firm hires a factor until its price = MRP (= VMP under perfect competition).
- Product exhaustion: Euler's theorem, constant returns to scale (Wicksteed).
- Ricardo: differential rent over no-rent land; price-determined.
- Economic rent = earnings − transfer earnings; quasi-rent = TR − TVC (Marshall).
- Real wage = money wage ÷ price index × 100.
- Backward-bending labour supply: income effect > substitution effect.
- Loanable funds: Wicksell, Robertson, Ohlin; liquidity preference: Keynes.
- Keynes's motives: transactions, precautionary, speculative; liquidity trap at very low rates.
- Profit: Clark dynamic, Schumpeter innovation, Hawley risk, Knight uncertainty.
- Fisher: nominal ≈ real + inflation.
Go deeper: Mains writing (beyond what APPSC Paper I usually asks)
Mains writing Mains writing
- Frame: functional distribution explains how national income is shared among land, labour, capital and enterprise.
- Analysis:
- Marginal productivity explains demand for factors; bargaining power, monopsony and institutions shape actual wages.
- Rising urban land prices are largely economic rent, which supports land value capture for infrastructure.
- Keynes's liquidity preference underlies how the RBI's policy rate and liquidity operations move market interest rates.
- Example: Schumpeter's innovation profit explains why start-ups earn high returns until competitors copy them.
Practise this topic. Questions on Factor pricing: rent, interest & profit, with answers explained.
All Microeconomics: demand, production, markets and factor pricing notes · APPSC Paper I syllabus · APPSC Paper I Mock 1 with answers · Start free
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