As a result of the Great Depression, a view that become very widespread among economists and others in the 1940s and 1950s was that:
the government should avoid interfering with the economic system and thus prevent another depression.
the business cycle was uncontrollable.
the market was inherently unstable, and thus needed a large dose of government guidance.
wage-price controls were an effective way to deal with inflation.
The Keynesian multiplier model implies that the source of instability in the economy is in:
the market for money balances.
markets for goods and services.