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Theories of Business Cycles for CA Foundation Business Economics

Updated 1 October 2026 · Fact-checked

Theories of business cycles explain why economies move through booms and slumps. Hawtrey blames credit and money flow, Keynes blames swings in investment and demand, Schumpeter blames clusters of innovation, Samuelson combines multiplier and accelerator, and real business cycle theory blames real shocks like technology. Match each theory to its single key cause to answer MCQs.

Understand Theories of Business Cycles

A business cycle is the repeated rise and fall of output, income and employment around the long-run growth path. Theories try to answer one question: what starts the swing, and what keeps it going?

Each theory picks a different main cause. If you remember the cause, you can answer most MCQs.

Hawtrey's monetary theory says the cycle is purely a monetary phenomenon. Banks expand credit, so traders borrow more, hold more stock, and demand rises. Prices and output rise. Later banks run short of reserves and cut credit. Demand falls and the economy slides. Hawtrey held that the cycle is caused by changes in the flow of money and credit, and that the trade cycle is mainly driven by short-term interest rates and credit.

Keynes's theory puts the cause in total demand, mainly investment. Investment depends on the expected return (marginal efficiency of capital) against the interest rate. When businesses turn optimistic, investment rises and the multiplier raises income. When expectations fall, investment drops and income falls by a multiple. Keynes stressed that unstable expectations and changes in investment drive the cycle.

Schumpeter's innovation theory says the cause is innovation by entrepreneurs: new products, methods or markets. A successful innovation brings imitators in clusters, which creates a boom. Later the gains fade, competition spreads, profits fall and the economy settles into recession until the next wave of innovations.

Samuelson's multiplier-accelerator model shows how two forces interact. The multiplier says a change in investment changes income by a larger amount. The accelerator says a change in income or output changes investment, because firms need more capital to produce more. Together they can produce self-feeding up and down movements. The real business cycle (RBC) view says fluctuations come from real shocks on the supply side, such as technology changes, resource changes or productivity shocks, and not from money or demand.

Key formulas to remember

Multiplier
k = ΔY ÷ ΔI = 1 ÷ (1 − MPC)
MPC is the marginal propensity to consume. A higher MPC gives a larger multiplier.
Accelerator
Investment ≈ v × ΔY, where v = capital-output ratio
Induced investment depends on the change in income or output, not its level.
Theory to cause match
Hawtrey → credit; Keynes → investment and expectations; Schumpeter → innovation; Samuelson → multiplier + accelerator; RBC → real (technology) shocks
Use this one-line map to answer most theory-matching MCQs.

How to solve Theories of Business Cycles questions

Use this method for any question that asks you to identify, match or compare a business cycle theory.

  1. 1Read the question and underline the cause words: credit, bank, interest, investment, expectations, innovation, multiplier, accelerator, technology.
  2. 2Map those cause words to the theory using the match rule: credit to Hawtrey, expectations and investment to Keynes, innovation to Schumpeter, multiplier plus accelerator to Samuelson, real shocks to RBC.
  3. 3Check whether the question asks for the main cause, the mechanism or the criticism. Pick the option that fits that exact ask.
  4. 4Remove options that name a different theory's cause, or that mix two theories.
  5. 5For numerical parts, apply k = 1 ÷ (1 − MPC) first, then use the accelerator if investment depends on change in output.
  6. 6Check the final option against the words 'only', 'purely' and 'always'. Accept them only where the theory really says so, such as Hawtrey's 'purely monetary'.

Quickest way: Keyword-to-theory match

When to use it: Use this for one-line MCQs where you must name the theory or its cause, so you can answer in under 30 seconds.

  1. Spot the keyword: credit = Hawtrey, innovation = Schumpeter, expectations or investment = Keynes, interaction of multiplier and accelerator = Samuelson, technology shock = RBC.
  2. Cross out options that give a different cause.
  3. If two options remain, choose the one that fits the exact word in the stem, such as 'purely monetary' or 'clusters'.
  4. If you cannot narrow to two options, skip. A wrong answer costs 0.25 marks.

Common mistakes in Theories of Business Cycles

  • Mixing up Keynes and Samuelson because both use the multiplier.

    Both theories involve investment and income changes.

    Fix: Keynes stresses expectations and investment changes. Samuelson specifically needs the multiplier and accelerator working together.

  • Saying Hawtrey's theory is about innovation or real factors.

    Students remember 'trade cycle' but not the cause.

    Fix: Link Hawtrey with credit, bank reserves and money flow. It is a monetary theory.

  • Thinking Schumpeter says a single innovation causes the cycle.

    The word 'innovation' sounds like one event.

    Fix: Remember clusters: innovations bunch together as imitators follow the first entrepreneur.

  • Treating the real business cycle view as a demand or monetary theory.

    Most textbook theories focus on demand or money.

    Fix: RBC focuses on real supply-side shocks such as technology and productivity changes.

  • Confusing the multiplier with the accelerator.

    Both link income and investment, but in opposite directions.

    Fix: Multiplier: investment change leads to income change. Accelerator: income change leads to investment change.

Worked examples

Example 1

According to Hawtrey, the business cycle is mainly caused by: (A) clusters of innovations (B) changes in the flow of money and credit (C) real technology shocks (D) interaction of the multiplier and accelerator

Show the solution
  1. Underline the cause: Hawtrey's theory is monetary.
  2. Innovation clusters belong to Schumpeter, so remove A.
  3. Technology shocks belong to the real business cycle view, so remove C.
  4. Multiplier and accelerator belong to Samuelson, so remove D.
  5. The remaining option is B.

Answer: (B) changes in the flow of money and credit

Example 2

Which theory explains the cycle through the interaction of the multiplier and the accelerator? (A) Schumpeter's theory (B) Hawtrey's theory (C) Samuelson's model (D) Real business cycle theory

Show the solution
  1. The keywords multiplier and accelerator point to one model.
  2. Schumpeter uses innovation and Hawtrey uses credit, so remove A and B.
  3. RBC uses real shocks, so remove D.
  4. Samuelson's model combines both forces.

Answer: (C) Samuelson's model

Example 3

If MPC is 0.8 and investment rises by ₹100 crore, what is the total rise in income through the multiplier? (A) ₹180 crore (B) ₹400 crore (C) ₹500 crore (D) ₹800 crore

Show the solution
  1. Multiplier k = 1 ÷ (1 − MPC) = 1 ÷ (1 − 0.8) = 1 ÷ 0.2 = 5.
  2. ΔY = k × ΔI = 5 × ₹100 crore = ₹500 crore.
  3. Check: ₹400 crore would be 4 times, which assumes MPC 0.75, so B is wrong.

Answer: (C) ₹500 crore

Exam tips

  • Learn the one-line cause for each theory. Most MCQs are direct matches.
  • Watch for words like 'purely monetary' (Hawtrey) and 'clusters' (Schumpeter). They are the usual hooks.
  • Do the multiplier calculation carefully: k = 1 ÷ (1 − MPC). Slips in arithmetic are a common way to lose marks.
  • If you are torn between two theories, skip and return. Negative marking is 0.25 per wrong answer.

Practice questions from Business Cycles

Theories of Business Cycles: frequently asked questions

What is Hawtrey's monetary theory of business cycle?

Hawtrey says the cycle is a purely monetary phenomenon. Expansion and contraction of bank credit changes the money flow, which changes demand, prices and output.

What is Schumpeter's innovation theory?

Schumpeter says cycles arise because entrepreneurs introduce innovations, and imitators follow in clusters. This creates a boom, and the economy slows when the gains from innovation fade.

How does Samuelson's model work in simple terms?

The multiplier turns a rise in investment into a larger rise in income. The accelerator turns that rise in income into more investment. Together they can produce repeated ups and downs.

How do Keynesian and monetary views of the cycle differ?

The Keynesian view focuses on changes in investment and expectations that move total demand. The monetary view, such as Hawtrey's, focuses on credit and money flow as the main cause.