According to John Maynard Keynes, employment depends upon effective demand. Effective demand refers to the aggregate demand for goods and services in an economy that is sufficient to create the demand for labor and maintain full employment. Keynes argued that employment is determined by the level of aggregate demand in the economy.

Keynesian theory and effective demand:
- Keynesian economics is a macroeconomic theory that emphasizes the role of aggregate demand in determining the level of economic activity and employment.
- According to Keynes, the level of employment in an economy is determined by the level of effective demand, which is the total spending on goods and services in the economy.
- Effective demand is composed of consumption expenditure by households, investment expenditure by businesses, government spending, and net exports.
- Keynes argued that fluctuations in aggregate demand can lead to fluctuations in employment. If aggregate demand is low, businesses will produce less, leading to a decrease in employment. Conversely, if aggregate demand is high, businesses will increase production and employment.
- Keynes believed that the government could play a role in stabilizing aggregate demand and promoting full employment through fiscal policy measures such as increasing government spending or reducing taxes during periods of low aggregate demand.

Importance of effective demand for employment:
- Effective demand is crucial for maintaining full employment in an economy. Without sufficient demand for goods and services, businesses will not have the incentive to hire workers or produce more.
- If there is a lack of effective demand, businesses may reduce their production levels, leading to layoffs and unemployment.
- Conversely, if there is strong effective demand, businesses will increase their production levels and hire more workers to meet the demand.
- Therefore, maintaining a high level of effective demand is essential for promoting employment and economic growth.

In conclusion, according to John Maynard Keynes, employment depends upon effective demand, which is the total spending on goods and services in an economy. Fluctuations in aggregate demand can lead to fluctuations in employment levels, and maintaining a high level of effective demand is crucial for promoting full employment and economic growth.