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Causes of Business Cycles – Demand, Supply & External Shocks

Why do economies experience booms and recessions? Economists explain business cycles using demand, supply and external factors.


1. Demand-side Causes

  • Changes in investment demand – optimistic expectations increase investment; pessimism reduces it.
  • Changes in consumption demand – due to income, wealth, credit availability.
  • Monetary policy – expansion of money supply can stimulate demand; tight policy can slow it.

2. Supply-side Causes

  • Technological changes – new inventions can start expansion.
  • Changes in cost of production – oil price shocks, wage changes.
  • Availability of inputs – shortages of raw materials, power cuts.

3. External Shocks

  • Wars and political disturbances.
  • Natural disasters, pandemics.
  • Global financial crises.

📋 Case Study: COVID-19 Shock

❗ Scenario:
The COVID-19 pandemic and lockdowns caused a sudden collapse in output, employment and trade in many countries.
💡 Analysis:
Governments and central banks announced fiscal stimulus, income support schemes, loan moratoriums and liquidity measures to support firms and households.
✅ Outcome:
Economies experienced a sharp recession in 2020, followed by gradual recovery as restrictions were eased and vaccination increased.
🎓 Key Learnings:
  • External shocks can quickly push an economy into recession
  • Both demand and supply sides can be hit at the same time
  • Timely policy support is crucial to stabilise output and employment

4. Interaction of Factors

Often, business cycles are caused by combination of factors:

  • Demand and supply changes feed into each other.
  • External shocks trigger changes in expectations and investment.
1"Shock to demand or supply"
2"Change in output, employment, income"
3"Further impact on expectations and investment"

5. Quick Revision Points

  • Demand-side: investment, consumption, monetary policy.
  • Supply-side: technology, cost, input availability.
  • External: wars, disasters, global crises.

6. Quiz Time 🎯

Test Your Knowledge

Question 1 of 5

1. Which is a demand-side cause of business cycles?

Technological innovation
Change in investment demand
Natural disaster
Oil price shock