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By the end of this section, you will be able to:
  • Explain Say’s Law and determine whether it applies in the short run or the long run
  • Explain Keynes’ Law and determine whether it applies in the short run or the long run

Macroeconomists over the last two centuries have often divided into two groups: those who argue that supply is the most important determinant of the size of the macroeconomy while demand just tags along, and those who argue that demand is the most important factor in the size of the macroeconomy while supply just tags along.

Say’s law and the macroeconomics of supply

Those economists who emphasize the role of supply in the macroeconomy often refer to the work of a famous French economist of the early nineteenth century named Jean-Baptiste Say (1767–1832). Say’s law    is: “Supply creates its own demand.” As a matter of historical accuracy, it seems clear that Say never actually wrote down this law and that it oversimplifies his beliefs, but the law lives on as useful shorthand for summarizing a point of view.

The intuition behind Say’s law is that each time a good or service is produced and sold, it generates income that is earned for someone: a worker, a manager, an owner, or those who are workers, managers, and owners at firms that supply inputs along the chain of production. The forces of supply and demand in individual markets will cause prices to rise and fall. The bottom line remains, however, that every sale represents income to someone, and so, Say’s law argues, a given value of supply must create an equivalent value of demand somewhere else in the economy. Because Jean-Baptiste Say, Adam Smith , and other economists writing around the turn of the nineteenth century who discussed this view were known as “classical” economists, modern economists who generally subscribe to the Say’s law view on the importance of supply for determining the size of the macroeconomy are called neoclassical economists    .

If supply    always creates exactly enough demand at the macroeconomic level, then (as Say himself recognized) it is hard to understand why periods of recession and high unemployment should ever occur. To be sure, even if total supply always creates an equal amount of total demand, the economy could still experience a situation of some firms earning profits while other firms suffer losses. Nevertheless, a recession    is not a situation where all business failures are exactly counterbalanced by an offsetting number of successes. A recession is a situation in which the economy as a whole is shrinking in size, business failures outnumber the remaining success stories, and many firms end up suffering losses and laying off workers.

Say’s law that supply creates its own demand    does seem a good approximation for the long run. Over periods of some years or decades, as the productive power of an economy to supply goods and services increases, total demand in the economy grows at roughly the same pace. However, over shorter time horizons of a few months or even years, recessions or even depressions occur in which firms, as a group, seem to face a lack of demand for their products.

Questions & Answers

how do you find the marginal line given the input and output?
Greatson Reply
population density
Thompson Reply
what is elasticity of demand?
tunde Reply
Elasticity is a central concept in economic , and is applied in many situations. Elasticity can provide important information about the strength or weakness of such relationship. Elasticity refers to the responsiveness of one economic variable such as quantity demanded, to change in another variable
Lena
such as price. #Price elasticity of demand:which measure the responsiveness of the quantity demanded to a change in price. #cross elasticity of demand:which measure the responsiveness of quantity demanded of one good to a change in the price of another good.
Lena
what are variables
Lekan Reply
marginal cost
Seyi Reply
division of labour
Abdulmumeen Reply
explain Qd=601/3p
mahmud Reply
what is unemployment
Ernest Reply
what is the formula for average revenues
EMMANUEL Reply
please 7 implications of Lionel Robbins definition of economics
Amaka Reply
Problem of economics to the society
Gmzaeeyan Reply
Within 1 or 2 percentage points, what has the U.S. inflation rate been during the last 20 years? Draw a graph to show the data.
Daphne Reply
law of demand is explaining why the demand curve is downward sloping
Tan Reply
the graph would be x axis is quantity and y axis is price, as the price is expensive, there would be less demand therefore less quantity anf vice versa, thats why demand curve is downward sloping
Tan
and*
Tan
problems of economic to the society
onalaja Reply
Income Price Taste of the commodity
Ubani Reply

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Source:  OpenStax, Principles of economics. OpenStax CNX. Sep 19, 2014 Download for free at http://legacy.cnx.org/content/col11613/1.11
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