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Keynes’ law and the macroeconomics of demand

The alternative to Say’s law, with its emphasis on supply, can be named Keynes’ law    : “Demand creates its own supply.” As a matter of historical accuracy, just as Jean-Baptiste Say never wrote down anything as simpleminded as Say’s law, John Maynard Keynes never wrote down Keynes’ law, but the law is a useful simplification that conveys a certain point of view.

When Keynes wrote his great work The General Theory of Employment, Interest, and Money during the Great Depression of the 1930s, he pointed out that during the Depression, the capacity of the economy to supply goods and services had not changed much. U.S. unemployment rates soared higher than 20% from 1933 to 1935, but the number of possible workers had not increased or decreased much. Factories were closed and shuttered, but machinery and equipment had not disappeared. Technologies that had been invented in the 1920s were not un-invented and forgotten in the 1930s. Thus, Keynes argued that the Great Depression—and many ordinary recessions as well—were not caused by a drop in the ability of the economy to supply goods as measured by labor, physical capital, or technology. He argued the economy often produced less than its full potential, not because it was technically impossible to produce more with the existing workers and machines, but because a lack of demand in the economy as a whole led to inadequate incentives for firms to produce. In such cases, he argued, the level of GDP in the economy was not primarily determined by the potential of what the economy could supply, but rather by the amount of total demand.

Keynes’ law seems to apply fairly well in the short run of a few months to a few years, when many firms experience either a drop in demand for their output during a recession or so much demand that they have trouble producing enough during an economic boom. However, demand cannot tell the whole macroeconomic story, either. After all, if demand was all that mattered at the macroeconomic level, then the government could make the economy as large as it wanted just by pumping up total demand through a large increase in the government spending component or by legislating large tax cuts to push up the consumption component. Economies do, however, face genuine limits to how much they can produce, limits determined by the quantity of labor, physical capital, technology, and the institutional and market structures that bring these factors of production together. These constraints on what an economy can supply at the macroeconomic level do not disappear just because of an increase in demand.

Combining supply and demand in macroeconomics

Two insights emerge from this overview of Say’s law with its emphasis on macroeconomic supply and Keynes’ law with its emphasis on macroeconomic demand. The first conclusion, which is not exactly a hot news flash, is that an economic approach focused only on the supply side or only on the demand side can be only a partial success. Both supply and demand need to be taken into account. The second conclusion is that since Keynes’ law applies more accurately in the short run and Say’s law applies more accurately in the long run, the tradeoffs and connections between the three goals of macroeconomics may be different in the short run and the long run.

Key concepts and summary

Neoclassical economists emphasize Say’s law, which holds that supply creates its own demand. Keynesian economists emphasize Keynes’ law, which holds that demand creates its own supply. Many mainstream economists take a Keynesian perspective, emphasizing the importance of aggregate demand, for the short run, and a neoclassical perspective, emphasizing the importance of aggregate supply, for the long run.

References

Keynes, John Maynard. The General Theory of Employment, Interest and Money . London: Palgrave Macmillan, 1936.

U.S. Department of Commerce: United States Census Bureau. “New Residential Sales: Historical Data.” http://www.census.gov/construction/nrs/historical_data/.

Questions & Answers

which model predicted a global collapse in the world's social and economic system before the year 2010
Francis Reply
what is the formula of mixed income ?
Sanjum Reply
labor force in.Nigeria is seen as .......?
Aisha Reply
Is demand the same as being in need of a product?
Aphiwe Reply
yeah
Demand is defer from only need of products
Zubairu
need is the primary and main root of demand. but demand is the result of combination of need; income capacity and desire to expend of money for that product.
Ramu
products or services
jax
what is price determination?
Alick Reply
why are imports subtructed when GDP is calculated in the expenditure approach
nati
what is fiscalpolicy
nati Reply
The way of the government expenses and other analysis
Zubairu
It explains government spending and how it helps to direct the economy towards the desired direction. For instance, if the govt of a nation is desirous of achieving economic growth and development, then the govt will adopt an expansionary fiscal policy which imply more spending by the govt.
Sunday
and politics party important
mujtaba Reply
politics party important
mujtaba
Which party is that
Zubairu
persons who stopped searching for jobs but would accept if the opportunity presents itself
Torissa Reply
persons who are unemployed whether they are underage, retired or incapacitated
Torissa
the us economy is best characterized as?
Shekeriah
what is the impact of fiscal policy in the short and long run in the AD/AS model...
Hydrammeh Reply
What is demand
Mohd Reply
Demand is the desire for a commodity backed by the willingness and the purchasing power too.
Ajay
what is the impact of the higher tax rate on the business and the economy at large..?
Hydrammeh Reply
aggregate demand decreases and GDP decreases in the long run prices will decrease because aggregate supply will shift to the right and increase
Murabit
Thanks, Murabit
Hydrammeh
But still I will need more explanation
Hydrammeh
no problem tax rate is a form of fiscal policy so any time the government changes spending or taxes it will directly affect the economy
Murabit
but remember that there at different economic views on fiscal policy there is classical,Keynesian and moneterism
Murabit
if taxes increase aggregate demand decreases causing a fall in prices causing a fall in the money demand lowering interest rate and increasing investment spending in turn increasing prices
Murabit
thanks so much Murabit
Hydrammeh
what are the policy recommendations for impact of government borrowing?
Baisiro Reply
how can I get Utility notes here
Tabea Reply
I also want to know
konglan
I have them
Alick
money and money supply
Yogesh Reply
money is anything that is generally accepted as payment of goods and services or that is accepted in settlement of debt.
Rakgadi
Money supply?
Rakgadi
Money supply is the total value of monetary assets available in an economy at a specific time.
Rakgadi
supply of money:- The total quantity of money in an economy at a point of time......
Ittoo
What is the difference between monetary economy and barter economy?
Rakgadi
monetary economy is simply an economy where money acts as a medium of exchange and barter economy is why where goods acts as a medium of exchange
Ittoo
Thank you Ittoo.
Rakgadi
please cut why.....in last ans
Ittoo
and no need of thanks dear
Ittoo
Don't damend work in inflation
Mishael Reply

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Source:  OpenStax, Macroeconomics. OpenStax CNX. Jun 16, 2014 Download for free at http://legacy.cnx.org/content/col11626/1.10
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