Question

Explain how saving-investment equality brings about equilibrium in the circular flow of income.

Answer 1

In a two-sector economy, which consists of both families and businesses, income is constantly flowing in the form of money flows (payments and consumption expenditures) and real flows (goods and factor services). Families obtain factor revenue in exchange for their factor services to businesses. This revenue is either consumption (C) or saved (S). In order to make investments (I), which are injections into the circular flow, businesses may borrow these savings from financial institutions. Equilibrium is achieved when S = I. This indicates that the money that was lost through savings is precisely put back into the economy through investment.

How Equilibrium Is Maintained by S = I

1. If S = I
   • All savings are invested in profitable businesses.
   • There is no shift in output or revenue.
   • The economy stays stable.
2. If S > I
   • More leaks than injections.
   • Reduced aggregate demand results in a drop in output and revenue.
   • The economy falls out of balance.
3. If I > S
   • Injections outnumber leaks.
   • When demand rises, output and income also rise.
   • The economy temporarily grows beyond equilibrium.

In both cases, market forces adjust income levels so that eventually S = I, and equilibrium is restored.

Example: The income flow stays the same if households save ₹ 1,000 crore and businesses invest ₹ 1,000 crore. However, if businesses only invest ₹ 800 crore, ₹ 200 crore goes unused, which lowers revenue. The economy regains equilibrium when savings drop to ₹ 800 crore as a result of decreasing income.