अर्थशास्त्र Economics

Quick summary

Macroeconomics studies the economy as a whole – total output, national income, employment, the general price level, money, growth and the balance of payments. The terms micro and macro were coined by Ragnar Frisch in 1933, and J. M. Keynes' General Theory (1936) made macroeconomics a separate branch. It deals with aggregates and is the basis of government policy.

Key points

• Meaning: the study of aggregates – aggregate demand, aggregate supply, total saving and investment, national income, general price level.
• Micro vs macro: microeconomics studies individual units (a consumer, a firm, the price of one good); macroeconomics studies the whole economy. Both are complementary.
• Scope: theory of national income; theory of employment; theory of money and prices (inflation, deflation); theory of economic growth; trade cycles; international trade and balance of payments; macroeconomic policy (monetary and fiscal).
• Importance: helps understand how the economy works; guides policy against unemployment and inflation; essential for planning and growth; helps compare economies; explains business fluctuations; resolves paradoxes such as the paradox of thrift.
• Limitations: fallacy of composition (what is true for one may not be true for all); aggregates hide differences within groups; statistical measurement problems; ignores individual welfare.
• Macro variables: stock variables (money supply, capital stock – measured at a point of time) and flow variables (income, investment – measured over a period).
• Static, comparative static and dynamic analysis: equilibrium at one time; comparison of two equilibria; path of change over time.
• Major macro goals: full employment, price stability, economic growth, balance-of-payments equilibrium, fair distribution.

Important terms

• Aggregate (समग्र) – total of a variable for the whole economy.
• Fallacy of composition – wrongly assuming that what is true for a part is true for the whole.
• Paradox of thrift – if everyone saves more, total saving may fall because income falls.
• Stock – quantity measured at a point of time.
• Flow – quantity measured over a period of time.

Key facts

• 1933 – Ragnar Frisch used the terms micro and macro.
• 1936 – Keynes, The General Theory of Employment, Interest and Money.

5 important questions

Q1. Define macroeconomics.

Macroeconomics is the branch of economics that studies aggregates, such as national income, total employment, the general price level and economic growth of the whole economy.

Q2. What is the paradox of thrift?

Saving is good for an individual, but if all people try to save more at the same time, aggregate demand and income fall, and total saving may not increase.

Q3. Explain the nature and scope of macroeconomics.

Outline: meaning and origin; nature (aggregative, policy-oriented, income theory); scope – national income, employment, money, inflation, growth, trade cycles, international economics, policy.

Q4. Discuss the importance and limitations of macroeconomics.

Outline: importance – working of the economy, policy making, planning, growth, inflation and unemployment control, paradoxes; limitations – fallacy of composition, heterogeneous aggregates, measurement problems, ignores structure.

Q5. Distinguish between microeconomics and macroeconomics and show their interdependence.

Outline: table of differences; interdependence – macro totals are sums of micro units, micro decisions depend on macro conditions (interest rates, inflation); conclusion – both needed.

Exam tip

Mention Frisch (1933) and Keynes (1936) in the introduction – dates in the first lines create a good impression.

Quick summary

National income is the total money value of all final goods and services produced by the normal residents of a country during one year, plus net income from abroad. It measures the economic performance of a country. This topic covers concepts (GDP, GNP, NNP, NI, PI, DI), the circular flow, methods of measurement and difficulties.

Key points

• Marshall: national income is the net aggregate of commodities and services produced by labour and capital acting on natural resources in a year.
• Pigou: that part of the objective income of the community which can be measured in money.
• Fisher: national income is based on consumption, not production.
• Circular flow of income: households supply factors to firms and receive income; firms sell goods to households and receive spending. Production = income = expenditure.
• GDP – value of final goods and services produced within the domestic territory in a year.
• GNP – GDP plus net factor income from abroad (NFIA).
• NNP – GNP minus depreciation.
• NNP at factor cost = National Income – NNP at market price minus net indirect taxes (indirect taxes − subsidies).
• Personal income – income actually received by individuals.
• Disposable income – personal income minus direct personal taxes.
• Concepts:
• Product (value added) method – add value added by all sectors (primary, secondary, tertiary).
• Income method – add rent, wages, interest and profit (plus mixed income).
• Expenditure method – add consumption (C), investment (I), government spending (G) and net exports (X − M).
• Methods of measurement:
• Only final goods are counted to avoid double counting.
• Not included: transfer payments (pensions, scholarships), sale of second-hand goods, purely financial transactions (shares), illegal income, unpaid housework.
• Difficulties in India: large non-monetised sector, lack of reliable data, illiteracy, unorganised sector, self-consumption by farmers, double counting risk.
• In India, national income is estimated by the National Statistical Office (NSO), formerly the Central Statistical Organisation (CSO), under the Ministry of Statistics and Programme Implementation.
• Real national income is measured at constant (base year) prices; nominal at current prices.

Important terms

• National income (राष्ट्रीय उत्पन्न) – total income of a nation in a year.
• Depreciation – wear and tear of fixed capital; also called consumption of fixed capital.
• Value added – value of output minus value of intermediate goods.
• Transfer payment – income received without any productive service in return.
• Per capita income – national income divided by population.
• GDP deflator – (nominal GDP ÷ real GDP) × 100.

Formulas

• GNP = GDP + NFIA
• NNP = GNP − Depreciation
• NI = NNP at factor cost = NNP at market price − Indirect taxes + Subsidies
• GDP (expenditure) = C + I + G + (X − M)
• Disposable income = Personal income − Direct taxes
• Per capita income = National income ÷ Population

5 important questions

Q1. What is GDP?

GDP is the market value of all final goods and services produced within the domestic territory of a country during one year, whether by residents or non-residents.

Q2. GDP at market price = Rs. 5,000 crore, NFIA = Rs. 200 crore, depreciation = Rs. 300 crore, net indirect taxes = Rs. 400 crore. Find national income.

• GNP at MP = 5,000 + 200 = 5,200.
• NNP at MP = 5,200 − 300 = 4,900.
• NNP at FC (NI) = 4,900 − 400 = Rs. 4,500 crore.

Q3. Explain the circular flow of income in a two-sector economy.

• Two sectors: households and firms.
• Real flow: factor services to firms; goods to households.
• Money flow: factor payments to households; consumption spending to firms.
• Income = expenditure = output.
• Leakages (saving) and injections (investment) in wider models.
• Diagram description.

Q4. Explain the methods of measuring national income.

• Product method: sectors, value added, avoid double counting.
• Income method: rent, wages, interest, profit, mixed income.
• Expenditure method: C + I + G + (X − M).
• Precautions for each method.
• All three give the same result in theory.

Q5. Explain the difficulties in measuring national income in India.

• Non-monetised transactions and self-consumption.
• Unorganised sector and lack of records.
• Illiteracy and poor data.
• Double counting.
• Black money and illegal activities.
• Changing prices and treatment of depreciation.

Exam tip

Learn the chain GDP → GNP → NNP → NI as a ladder; most numerical questions only test this ladder.

Quick summary

The classical economists (Adam Smith, Ricardo, J.B. Say, Pigou) believed the economy automatically moves to full employment. The Great Depression of the 1930s proved this wrong. J.M. Keynes, in The General Theory of Employment, Interest and Money (1936), showed that employment depends on effective demand, and that equilibrium can occur below full employment.

Key points

• Classical theory rests on Say's Law of Markets: "supply creates its own demand". Whatever is produced is sold, so general over-production and general unemployment are impossible.
• Assumptions: perfect competition, flexible wages and prices, flexible interest rate, no government interference, long-run view, money is only a medium of exchange (neutral).
• If unemployment appears, wages fall and more workers are employed (Pigou's wage-cut policy). If saving exceeds investment, the interest rate falls so that saving = investment.
• Only frictional and voluntary unemployment can exist in the classical system.
• Keynes' criticism: wages are rigid downward; a wage cut reduces income and demand; saving and investment are decided by different people; the economy can stay in underemployment equilibrium; "in the long run we are all dead".
• Keynesian theory: employment depends on effective demand. Effective demand is the point where aggregate demand (ADF) = aggregate supply (ASF).
• Aggregate supply price is the minimum receipts entrepreneurs need to offer a given level of employment. The ASF curve slopes upward and becomes vertical at full employment.
• Aggregate demand price is the receipts entrepreneurs expect from selling the output of a given employment. AD = C + I (in a closed economy without government).
• Effective demand depends on consumption (propensity to consume) and investment (marginal efficiency of capital and rate of interest).
• Keynes recommended government intervention: public works, deficit spending, cheap money policy, to raise effective demand.
• The Keynesian revolution gave birth to modern macroeconomics.

Important terms

• Full employment – all who are willing and able to work at the current wage get work.
• Effective demand (प्रभावी मागणी) – aggregate demand at the point where it equals aggregate supply.
• Involuntary unemployment – people willing to work at current wage but not getting work.
• Underemployment equilibrium – equilibrium with some involuntary unemployment.
• Say's Law – supply creates its own demand.
• Deficit financing – government spending more than its revenue to raise demand.

Important thinkers and theories

• Classical: S = I through interest-rate flexibility.
• Keynes: Y = C + I; equilibrium where AD = AS; S = I through changes in income.

5 important questions

Q1. What is Say's Law of Markets?

J.B. Say's law states that supply creates its own demand. Every production creates income equal to its value, which is spent, so general overproduction and unemployment cannot occur.

Q2. What is effective demand?

Effective demand is that level of aggregate demand which equals aggregate supply. At this point the entrepreneurs' expected receipts equal their required receipts, so it decides the level of employment.

Q3. Explain the classical theory of employment and its assumptions.

• Say's law.
• Wage-price flexibility; Pigou's wage cut.
• Interest flexibility makes S = I.
• Money neutral; laissez-faire.
• Conclusion: full employment is normal.

Q4. Critically examine Keynes' criticism of the classical theory.

• Say's law invalid; not all income is spent.
• Wage rigidity; wage cut lowers demand.
• S and I equalised by income, not interest.
• Long-run view unrealistic.
• Great Depression evidence.
• Need for state intervention.

Q5. Explain the Keynesian principle of effective demand with a diagram.

• Meaning of ADF and ASF.
• Diagram: ASF rising then vertical; ADF rising; intersection at E.
• Employment determined at E, may be less than full employment.
• Determinants: consumption and investment.
• Policy implications.

Exam tip

Use the phrase "underemployment equilibrium" in every Keynes answer, and always mention the year 1936 and the book's title.

Quick summary

The consumption function shows the relation between income and consumption. Keynes' psychological law of consumption says that consumption rises when income rises, but by less than the rise in income. The investment multiplier, developed by R.F. Kahn (employment multiplier, 1931) and Keynes (investment multiplier), shows how an increase in investment raises income by a larger amount.

Key points

• Consumption function: C = f(Y). Keynes' linear form: C = a + bY, where a is autonomous consumption and b is MPC.
• Average propensity to consume (APC) = C/Y. Marginal propensity to consume (MPC) = ΔC/ΔY.
• When income rises, consumption rises, but less than income.
• The increase in income is divided between consumption and saving.
• A rise in income will not lead to a fall in consumption or saving.
• Keynes' psychological law (three propositions):
• MPC lies between 0 and 1. APC falls as income rises.
• Saving function: S = Y − C. APS = S/Y, MPS = ΔS/ΔY. MPC + MPS = 1; APC + APS = 1.
• Subjective factors affecting consumption: precaution, foresight, improvement, independence, enterprise, pride, avarice (Keynes' motives to save).
• Objective factors: income distribution, fiscal policy, interest rate, windfall gains, price changes, credit facilities.
• Multiplier (k): the ratio of change in income to the change in investment. k = ΔY/ΔI = 1/(1 − MPC) = 1/MPS.
• The higher the MPC, the higher the multiplier.
• Working: extra investment becomes income of some people; they spend part of it; that spending becomes others' income — a chain of rounds.
• Leakages that reduce the multiplier: saving, taxes, imports, debt repayment, hoarding, buying old shares or second-hand goods.
• Assumptions: constant MPC, no time lag, closed economy, unemployed resources available.
• The multiplier works in reverse too: a fall in investment lowers income by a multiple.

Important terms

• Propensity to consume (उपभोग प्रवृत्ती) – tendency to spend out of income.
• Autonomous consumption (a) – consumption at zero income.
• Break-even point – income at which C = Y and saving is zero.
• Leakage – part of income not passed on as spending.
• Paradox of thrift – if all people try to save more, total saving may not rise because income falls.

Formulas

• C = a + bY
• APC = C/Y; MPC = ΔC/ΔY
• APS = S/Y; MPS = ΔS/ΔY
• MPC + MPS = 1; APC + APS = 1
• k = ΔY/ΔI = 1/(1 − MPC) = 1/MPS
• ΔY = k × ΔI

5 important questions

Q1. If MPC = 0.75, find the multiplier.

k = 1/(1 − MPC) = 1/(1 − 0.75) = 1/0.25 = 4.

Q2. Investment rises by Rs. 500 crore and MPS = 0.2. Find the rise in income.

• k = 1/MPS = 1/0.2 = 5.
• ΔY = k × ΔI = 5 × 500 = Rs. 2,500 crore.

Q3. Explain Keynes' psychological law of consumption.

• Statement and three propositions.
• Assumptions: normal conditions, constant psychology, capitalist economy.
• Schedule and diagram: C curve flatter than 45° line.
• Implications: gap between Y and C must be filled by investment; importance of investment; danger of over-saving.

Q4. Explain the investment multiplier with a numerical example and its leakages.

• Meaning; k = 1/(1 − MPC).
• Example with MPC = 0.8: Rs. 100 investment → rounds 100, 80, 64 ... total 500.
• Leakages: saving, taxes, imports, debt repayment, hoarding.
• Assumptions and limitations.
• Importance in policy (public works).

Q5. Explain the factors that determine the consumption function.

• Subjective factors: motives to save.
• Objective factors: income distribution, fiscal policy, interest rate, windfall gains, expectations, credit, price level.
• Short run consumption function is stable.

Exam tip

Write the multiplier formula and substitute values neatly. Always mention that the multiplier is larger when MPC is larger.

Quick summary

Investment means spending on new capital goods such as machines, buildings and stocks, which adds to the productive capacity of the economy. Keynes explained investment through the marginal efficiency of capital (MEC) and the rate of interest. The accelerator (J.M. Clark, 1917) shows how a change in consumption demand causes a larger change in investment.

Key points

• In economics, investment means real investment (new capital goods), not buying shares or old assets (financial investment).
• Gross investment = total spending on capital goods. Net investment = gross investment − depreciation.
• Induced investment depends on income and profit; it rises with income. Autonomous investment does not depend on income; it is done for long-term or social reasons (roads, dams, defence, research).
• Determinants of investment (Keynes): the MEC and the rate of interest. Investment continues until MEC = rate of interest.
• MEC is the expected rate of return on an additional unit of a capital asset. It depends on the prospective yield and the supply price (cost) of the asset.
• MEC falls as investment increases, because the supply price of capital goods rises and prospective yields fall.
• Factors affecting MEC: expectations of businessmen, demand for goods, technology, government policy, population growth, price trends, political stability. Keynes stressed "animal spirits".
• Accelerator principle: net investment depends on the change in consumption (or output), not its level. A small change in consumption leads to a much larger change in investment.
• Accelerator coefficient (v or β) = ΔI/ΔC, which equals the capital-output ratio.
• Assumptions of accelerator: no excess capacity, constant capital-output ratio, quick supply of capital goods, demand increase is permanent.
• Multiplier vs accelerator: multiplier shows the effect of investment on income; accelerator shows the effect of change in income/consumption on investment.
• Super-multiplier (Hicks) / interaction: Paul Samuelson (1939) combined the multiplier and accelerator to explain trade cycles.

Important terms

• Investment (गुंतवणूक) – addition to the stock of real capital.
• Prospective yield – expected net returns from an asset over its life.
• Supply price – the cost of producing a new unit of the asset (replacement cost).
• Capital-output ratio – capital needed to produce one unit of output.
• Trade cycle – regular ups and downs in economic activity: boom, recession, depression, recovery.

Formulas

• Net investment = Gross investment − Depreciation
• MEC: supply price Cs = R₁/(1 + r) + R₂/(1 + r)² + ... + Rn/(1 + r)ⁿ, where R = expected yields and r = MEC
• Investment is undertaken while MEC > rate of interest; equilibrium at MEC = i
• Accelerator: v = ΔI/ΔC (or In = v × ΔY)
• Required capital K = v × Y

5 important questions

Q1. Distinguish between induced and autonomous investment.

Induced investment depends on changes in income and profit, and rises when income rises. Autonomous investment is independent of income; it is usually made by government for public welfare, e.g. dams and roads.

Q2. Capital-output ratio is 3. Consumption demand rises from Rs. 100 crore to Rs. 120 crore. Find induced net investment.

• ΔC = 120 − 100 = 20.
• Net investment = v × ΔC = 3 × 20 = Rs. 60 crore.

Q3. Explain the concept of marginal efficiency of capital and its determinants.

• Meaning; prospective yield and supply price.
• MEC curve slopes downward.
• Equilibrium where MEC = rate of interest.
• Short-run factors: expectations, demand, liquid assets.
• Long-run factors: population, technology, government policy.

Q4. Explain the accelerator principle with an example.

• Meaning; J.M. Clark.
• Table: machines needed per unit output; change in demand → change in investment.
• Assumptions.
• Limitations: excess capacity, expectations, supply limits.
• Role in trade cycles.

Q5. Distinguish between multiplier and accelerator and explain their interaction.

• Multiplier: ΔY/ΔI; Kahn and Keynes.
• Accelerator: ΔI/ΔC; Clark.
• Direction of causation.
• Samuelson's interaction model and trade cycles.
• Combined effect = super-multiplier.

Exam tip

In the accelerator, remember that investment depends on the change in demand. Use a small table showing machines needed each year to explain it clearly.

Quick summary

A trade cycle (business cycle) is the wave-like rise and fall of economic activity – output, income, employment and prices – over a period of years. Every cycle has four phases: expansion, peak, contraction and trough. Economists have explained cycles through monetary factors (Hawtrey), over-investment (Hayek), psychological factors (Pigou), innovations (Schumpeter), Keynes' MEC, and the multiplier-accelerator interaction (Samuelson, Hicks).

Key points

• Definition (Keynes): "A trade cycle is composed of periods of good trade characterised by rising prices and low unemployment percentages, alternating with periods of bad trade characterised by falling prices and high unemployment percentages."
• Features: wave-like movement; recurring but not exactly periodic; affects all sectors together; cumulative (a rise feeds further rise); capital-goods industries fluctuate more than consumer-goods industries; international spread.
• Expansion (recovery/prosperity) – rising investment, output, employment, prices and profits.
• Peak (boom) – full use of capacity, shortages, inflation, rising interest rates.
• Contraction (recession) – falling demand, profits, investment and employment.
• Trough (depression) – lowest output, mass unemployment, idle capacity, low prices; e.g. the Great Depression of 1929–33.
• Four phases:
• Monetary theory (R. G. Hawtrey) – changes in bank credit cause cycles.
• Over-investment theory (Hayek) – credit-led investment beyond savings causes imbalance.
• Psychological theory (Pigou) – waves of optimism and pessimism among businessmen.
• Innovation theory (Schumpeter) – clusters of innovations start booms.
• Keynes – fluctuations in the marginal efficiency of capital cause changes in investment and income.
• Samuelson's multiplier-accelerator interaction – investment raises income (multiplier), higher income raises investment (accelerator); the interaction produces cycles.
• Theories:
• Control: monetary policy (repo rate, CRR), fiscal policy (public works, taxes), automatic stabilisers, price and wage policies, international co-operation.

Important terms

• Recession (मंदी) – a fall in real GDP for two successive quarters (common working definition).
• Depression – a deep and long recession.
• Boom – the peak of prosperity with full employment and rising prices.
• Turning points – the upper turning point (peak) and lower turning point (trough).
• Automatic stabilisers – taxes and transfers that reduce fluctuations without new decisions.

Formulas

• Multiplier: k = 1 / (1 − MPC)
• Accelerator: Iₜ = v × (Yₜ − Yₜ₋₁), where v = capital-output ratio
• Samuelson's model: Yₜ = Cₜ + Iₜ + G, with Cₜ = b·Yₜ₋₁ and Iₜ = v(Cₜ − Cₜ₋₁)

5 important questions

Q1. Define a trade cycle.

A trade cycle is a recurring wave-like movement of economic activity in which periods of prosperity alternate with periods of depression.

Q2. Name the four phases of a trade cycle.

Expansion (recovery), peak (boom), contraction (recession) and trough (depression).

Q3. Explain the phases of a trade cycle with a diagram.

Outline: diagram of a wave around the trend line; features of each phase (investment, employment, prices, profits, credit, interest); turning points; example (2008 global crisis, 2020 COVID recession).

Q4. Explain Samuelson's multiplier-accelerator interaction theory of trade cycles.

Outline: meaning of multiplier and accelerator; how they interact; values of MPC and v giving different paths (damped, explosive, constant); Hicks' ceiling and floor; criticisms.

Q5. Discuss the measures to control trade cycles.

Outline: monetary (bank rate, open market operations, CRR, selective credit control); fiscal (public expenditure, taxes, budget surplus/deficit); others (automatic stabilisers, wage-price policy, international co-operation); limitations.

Exam tip

A neat four-phase wave diagram with a trend line and labelled turning points is expected in every long answer on this topic.

Quick summary

Money is anything that is generally accepted as a medium of exchange and measure of value. It removed the difficulties of the barter system. This topic covers the evolution of money, its functions, kinds, the value of money (quantity theory) and money supply measures in India.

Key points

• Definition (Crowther): money is anything that is generally acceptable as a means of exchange and at the same time acts as a measure and a store of value.
• Walker: "Money is what money does."
• Barter system problems: lack of double coincidence of wants, no common measure of value, indivisibility of goods, difficulty of storing value, no standard of deferred payments.
• Evolution: commodity money → metallic money → paper money → bank (credit) money → plastic and digital money (cards, UPI).
• Primary: medium of exchange, measure of value.
• Secondary: standard of deferred payments, store of value, transfer of value.
• Contingent: basis of credit, distribution of national income, equalising marginal utilities, liquidity.
• Functions of money (couplet: "Money is a matter of functions four — a medium, a measure, a standard, a store"):
• Kinds of money: full-bodied and token money; legal tender (limited and unlimited) and optional money; fiat money.
• Fisher's quantity theory of money (1911): MV = PT. Other things constant, the price level changes in direct proportion to the quantity of money.
• Cambridge cash-balance approach (Marshall, Pigou, Keynes, Robertson): demand for money to hold; Pigou's equation P = kR/M.
• Money supply measures in India (RBI): M1 (narrow money) = currency with public + demand deposits with banks + other deposits with RBI. M3 (broad money) = M1 + time deposits with banks.
• Gresham's Law: bad money drives good money out of circulation.

Important terms

• Money (पैसा) – generally accepted medium of exchange.
• Legal tender – money that must be accepted by law in payment of debts.
• Fiat money – money declared by government, without intrinsic value.
• Velocity of money (V) – number of times a unit of money changes hands in a period.
• Liquidity – ease with which an asset can be converted into money.
• Near money – assets easily changed into money, e.g. bills, bonds.

Formulas

• Fisher: MV = PT, so P = MV/T
• Extended: MV + M'V' = PT (M' = bank money, V' = its velocity)
• Pigou: P = kR/M (P = value or purchasing power of money, not the price level; k = proportion of real income held as money, R = real income, M = supply of money)
• M1 = C + DD + OD
• M3 = M1 + Time deposits

5 important questions

Q1. What is meant by double coincidence of wants?

In barter, an exchange is possible only when each person has what the other wants and wants what the other has. Finding such a match is very difficult.

Q2. M = Rs. 1,000 crore, V = 5, T = 2,500 crore units. Find the price level. What happens if M doubles?

• P = MV/T = (1,000 × 5)/2,500 = 2.
• If M = 2,000: P = (2,000 × 5)/2,500 = 4. Price level doubles.

Q3. Explain the functions of money.

• Primary: medium of exchange, measure of value.
• Secondary: deferred payments, store of value, transfer of value.
• Contingent: credit, distribution, liquidity, maximising satisfaction.
• Static and dynamic roles in the economy.

Q4. Explain Fisher's quantity theory of money and its criticism.

• Equation MV = PT and its terms.
• Assumptions: V and T constant, P passive, long run, full employment.
• Conclusion: P ∝ M.
• Criticism: unrealistic assumptions, ignores interest rate and demand for money, truism, static, only long run.

Q5. Explain the evolution of money.

• Barter and its defects.
• Commodity money (cattle, grain, shells).
• Metallic money and coins.
• Paper money and representative money.
• Bank/credit money, cheques.
• Electronic and digital money in India: cards, NEFT, UPI.

Exam tip

Write the couplet on functions of money at the start of the answer; it shows you remember the classification.

Quick summary

The value of money is its purchasing power, which moves inversely with the price level. The quantity theory of money explains the value of money through the supply of money (Fisher's transactions approach) and the demand to hold money (Cambridge cash-balance approach). Keynes linked the demand for money to the rate of interest through liquidity preference and restated the quantity theory.

Key points

• Value of money = 1 / Price level. When prices rise, the value of money falls.
• Fisher's equation (1911): MV + M′V′ = PT. M = money in circulation, V = its velocity, M′ = bank (credit) money, V′ = its velocity, P = price level, T = volume of transactions.
• Assuming V, V′, T and the ratio M′/M are constant in the short run, P changes in direct proportion to M; the value of money (1/P) changes inversely.
• Criticisms of Fisher: assumes full employment; V and T are not constant; a truism (identity); ignores interest rate and demand for money; long-run only; P is passive.
• Marshall: M = KPY; Pigou: P = KR/M (here P is the value of money); Keynes' real balance equation: n = pk.
• K is the proportion of income people keep as money.
• Cambridge (cash-balance) approach – Marshall, Pigou, Robertson, Keynes (early): value of money depends on the demand to hold money as cash balances.
• Cambridge approach is superior: stresses demand for money, explains short-run, introduces human motives; but K is also not constant and it ignores interest.
• Keynes' theory of demand for money: transactions motive and precautionary motive depend on income (L1); speculative motive depends inversely on interest (L2). L = L1(Y) + L2(i).
• Keynes' reformulated quantity theory: an increase in M raises output and employment until full employment; only after full employment does it raise prices proportionately (true inflation).
• Milton Friedman (1956) restated the quantity theory as a theory of demand for money as an asset (monetarism).

Important terms

• Value of money (पैशाचे मूल्य) – the quantity of goods and services one unit of money can buy.
• Velocity of circulation – number of times a unit of money changes hands in a year.
• Cash balance – money people hold with them.
• K (Cambridge K) – fraction of income held in cash.
• Speculative motive – holding money to profit from future changes in bond prices/interest.

Formulas

• Fisher: P = (MV + M′V′) / T
• Cambridge (Marshall): M = KPY → P = M / (KY)
• Keynes: L = L1(Y) + L2(i)

Worked example (Fisher): M = ₹1,000 crore, V = 4, M′ = ₹500 crore, V′ = 2, T = 500 crore units.
P = (1,000 × 4 + 500 × 2) / 500 = 5,000 / 500 = 10. If M and M′ double, P = 10,000 / 500 = 20 – prices double, value of money halves.

5 important questions

Q1. What is meant by the value of money?

The value of money is its purchasing power – the amount of goods and services one unit of money can buy. It is the reciprocal of the general price level (1/P).

Q2. Write Fisher's equation of exchange and explain its symbols.

MV + M′V′ = PT, where M = currency, V = its velocity, M′ = credit money, V′ = its velocity, P = price level, T = total transactions.

Q3. Explain and evaluate Fisher's quantity theory of money.

Outline: statement; equation; assumptions; diagram of P rising proportionately with M and 1/P falling; criticisms (identity, constant V and T, full employment, ignores interest, long run).

Q4. Explain the Cambridge cash-balance approach and compare it with Fisher's version.

Outline: Marshall, Pigou, Robertson, Keynes equations; meaning of K; comparison table (demand vs supply of money, stock vs flow, short run vs long run, T vs Y); merits and limitations.

Q5. Explain Keynes' theory of demand for money.

Outline: three motives; L1 depends on Y, L2 on i; total demand curve; liquidity trap; reformulated quantity theory (output effect before full employment); criticisms.

Exam tip

Solve a short Fisher numerical in your answer – doubling M to show doubling of P makes the proportional relation crystal clear.

Quick summary

The IS-LM model, developed by J. R. Hicks (1937) and popularised by Alvin Hansen, combines the goods market and the money market to find the equilibrium level of income and the rate of interest together. It removed the "indeterminacy" in both classical and Keynesian interest theories and is a standard tool to show the effects of monetary and fiscal policy.

Key points

• IS curve (Investment = Saving): combinations of interest rate (i) and income (Y) at which the goods market is in equilibrium. It slopes downward: a lower i raises investment, which through the multiplier raises Y.
• LM curve (Liquidity preference = Money supply): combinations of i and Y at which the money market is in equilibrium. It slopes upward: higher Y raises transactions demand for money; with fixed money supply, i must rise to reduce speculative demand.
• General equilibrium: the intersection of IS and LM gives the unique equilibrium rate of interest and level of income where both markets clear.
• Shifts of IS: rise in government spending, autonomous investment or exports, or a tax cut → IS shifts right → Y and i both rise (expansionary fiscal policy).
• Shifts of LM: rise in money supply → LM shifts right → Y rises and i falls (expansionary monetary policy). A rise in money demand shifts LM left.
• Three ranges of LM: Keynesian range (flat, liquidity trap – monetary policy ineffective, fiscal policy fully effective); intermediate range; classical range (vertical – fiscal policy ineffective due to full crowding out, monetary policy effective).
• Crowding out: higher government spending raises i, which reduces private investment.
• Limitations: assumes fixed price level; interest-elastic investment assumed; static; ignores expectations and the open economy (extended later in the IS-LM-BP / Mundell-Fleming model).

Important terms

• IS curve (IS वक्र) – locus of goods-market equilibrium points.
• LM curve – locus of money-market equilibrium points.
• Crowding out (बाह्यनिष्कासन) – fall in private investment due to higher government borrowing/interest.
• Liquidity trap – flat LM range where more money cannot lower interest.
• Policy mix – combined use of fiscal and monetary policy.

Formulas

• Goods market: Y = C + I + G, with C = a + bY and I = e − d·i.
• Money market: M/P = kY − h·i.

Worked example: C = 100 + 0.8Y, I = 150 − 10i, G = 50 → IS: Y = 300 + 0.8Y − 10i → 0.2Y = 300 − 10i → Y = 1500 − 50i.
Money: M = 300, L = 0.25Y − 12.5i → LM: 0.25Y = 300 + 12.5i → Y = 1200 + 50i.
Solve: 1500 − 50i = 1200 + 50i → 300 = 100i → i = 3%, Y = 1350 (check: 1200 + 150 = 1350).

5 important questions

Q1. What does the IS curve show?

It shows the combinations of interest rate and income level at which planned investment equals saving, i.e. the goods market is in equilibrium. It slopes downward.

Q2. What does the LM curve show?

It shows the combinations of interest rate and income at which the demand for money equals the supply of money. It slopes upward.

Q3. Explain the derivation of the IS and LM curves.

Outline: IS – four-quadrant diagram (investment function, I = S, saving function, IS); LM – four-quadrant diagram (L2, money supply split, L1, LM); reasons for slopes.

Q4. Explain the simultaneous determination of income and interest in the IS-LM framework.

Outline: Hicks-Hansen synthesis; diagram of IS and LM intersecting at E; disequilibrium points and adjustment; stability; significance.

Q5. Using IS-LM, explain the relative effectiveness of monetary and fiscal policy.

Outline: shifts of IS and LM; Keynesian, intermediate and classical ranges; crowding out; liquidity trap; policy mix; limitations of the model.

Exam tip

Label the axes correctly – interest rate (i) on the Y-axis and income (Y) on the X-axis – and mark E clearly at the intersection.