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By the end of this section, you will be able to:

  • Interpret a circular flow diagram
  • Explain the importance of economic theories and models
  • Describe goods and services markets and labor markets

John maynard keynes

The image is a photograph of John Maynard Keynes.
One of the most influential economists in modern times was John Maynard Keynes. (Credit: Wikimedia Commons)

John Maynard Keynes (1883–1946), one of the greatest economists of the twentieth century, pointed out that economics is not just a subject area but also a way of thinking. Keynes, shown in [link] , famously wrote in the introduction to a fellow economist’s book: “[Economics] is a method rather than a doctrine, an apparatus of the mind, a technique of thinking, which helps its possessor to draw correct conclusions.” In other words, economics teaches you how to think, not what to think.

Watch this video about John Maynard Keynes and his influence on economics.

Economists see the world through a different lens than anthropologists, biologists, classicists, or practitioners of any other discipline. They analyze issues and problems with economic theories that are based on particular assumptions about human behavior, that are different than the assumptions an anthropologist or psychologist might use. A theory    is a simplified representation of how two or more variables interact with each other. The purpose of a theory is to take a complex, real-world issue and simplify it down to its essentials. If done well, this enables the analyst to understand the issue and any problems around it. A good theory is simple enough to be understood, while complex enough to capture the key features of the object or situation being studied.

Sometimes economists use the term model    instead of theory. Strictly speaking, a theory is a more abstract representation, while a model is more applied or empirical representation. Models are used to test theories, but for this course we will use the terms interchangeably.

For example, an architect who is planning a major office building will often build a physical model that sits on a tabletop to show how the entire city block will look after the new building is constructed. Companies often build models of their new products, which are more rough and unfinished than the final product will be, but can still demonstrate how the new product will work.

A good model to start with in economics is the circular flow diagram    , which is shown in [link] . It pictures the economy as consisting of two groups—households and firms—that interact in two markets: the goods and services market    in which firms sell and households buy and the labor market    in which households sell labor to business firms or other employees.

The circular flow diagram

The circular flow diagram’s outer arrows represent a goods and services market, and the inner arrows represent a labor market. As illustrated by the outer arrows, in a goods and services market, firms give goods and services to households and, in exchange, households give payment to firms. As illustrated by the inner arrows, in a labor market, households provide labor to firms and, in exchange, firms give wages, salaries, and benefits to households.
The circular flow diagram shows how households and firms interact in the goods and services market, and in the labor market. The direction of the arrows shows that in the goods and services market, households receive goods and services and pay firms for them. In the labor market, households provide labor and receive payment from firms through wages, salaries, and benefits.

Of course, in the real world, there are many different markets for goods and services and markets for many different types of labor. The circular flow diagram simplifies this to make the picture easier to grasp. In the diagram, firms produce goods and services, which they sell to households in return for revenues. This is shown in the outer circle, and represents the two sides of the product market (for example, the market for goods and services) in which households demand and firms supply. Households sell their labor as workers to firms in return for wages, salaries and benefits. This is shown in the inner circle and represents the two sides of the labor market in which households supply and firms demand.

This version of the circular flow model is stripped down to the essentials, but it has enough features to explain how the product and labor markets work in the economy. We could easily add details to this basic model if we wanted to introduce more real-world elements, like financial markets, governments, and interactions with the rest of the globe (imports and exports).

Economists carry a set of theories in their heads like a carpenter carries around a toolkit. When they see an economic issue or problem, they go through the theories they know to see if they can find one that fits. Then they use the theory to derive insights about the issue or problem. In economics, theories are expressed as diagrams, graphs, or even as mathematical equations. (Do not worry. In this course, we will mostly use graphs.) Economists do not figure out the answer to the problem first and then draw the graph to illustrate. Rather, they use the graph of the theory to help them figure out the answer. Although at the introductory level, you can sometimes figure out the right answer without applying a model, if you keep studying economics, before too long you will run into issues and problems that you will need to graph to solve. Both micro and macroeconomics are explained in terms of theories and models. The most well-known theories are probably those of supply and demand, but you will learn a number of others.

Key concepts and summary

Economists analyze problems differently than do other disciplinary experts. The main tools economists use are economic theories or models. A theory is not an illustration of the answer to a problem. Rather, a theory is a tool for determining the answer.

Questions & Answers

production possibility curve
Mama Reply
graphs about production possibility curve?
what are the concept of economic
dauda Reply
demand suply and population
graphs on about ppc
with the aid of diagrams illustrate movement along and shifts in demand curve
Mercy Reply
what is scarcity
ISAH Reply
limited in supply relative to demand
scarcity means resources available to provide our daily needs are limited
shortage of resources that we need for our demand. basically price go up due to this problem.
scarcity means our resources r not enough for us or our resources r limited
discuss the effects of price controls int the economy
• It stimulates excess demand, which cannot be statified ie shortage in the market. • It encourages hoarding of commodities by wholesales and retailers. • It leads to the creation of " black market" or undercounter sales and its attendant high prices. • It encourage conditional sales of products.
on how scarcity,choice and opportunity cost work together
means less than requirement
What are the reasons for the existence of monopoly?
Gerry Reply
Because such barriers occur in different forms, there are therefore varying reasons for the existence of monopolies. Ownership of a Key Resource: When one company exerts sole control over a resource that is necessary for the production of a specific product, the market may become a monopoly.
Thanks Kenneth
what is international trade
Syed Reply
what is imperfect compition
what is crowding out effect
what is federal finance?
what is populic
what is imperfect compition
Explain five importance of the study of economic
Francis Reply
study of economics help a person to make rational choice in multiple wants. help individual to be a well all-round thinker.
the five important of the study of economics are as follows (1)time (2)management of resources (3)choice making (4)business(5)scarcity
an increase in demand (while supply remains constant) what will happen to deh graph?
Thabiso Reply
what is going to happen to the graph if there is an increase in demand, While supply remains constant .
What will happen to the graph if there is an increase in demand While supply remains constant?
price will increase high than automatically demand will decrease
equilibrium ?
is when the supply and demand are balanced
what is demand
Sarkwah Reply
demand is the willingness to buy a commodity backed by the ability to pay.
demand is mere desire on commodity with ability to back up with purchasing power
demand is the want of commodity back by the ability to pay for that commodity
demand is the willingness to buy any type of commodity for the exchange of something that is valuable to the seller.
demand is any valuable commodity that people are willing to buy at prices.
Equilibrium is when there's an equality between quantity demanded and quantity supplied
Victory Reply
Again the consumer will be in equilibrium if the price of the commodity is equal to Marginal utility of that product
wat is the law of supply
Agnes Reply
It's what* -The law of supply states that price and supply is relative. As all factors are equal, if price increases then quantity of supply there for increases.
the law of suppy state that when prise is high, more commodity with be supply and when p is low less of the same commodity will be supply.
It states that, "other things being equal, move supplied at a higher price than at a lower price ".
it's state that the increased in prices will lead to decreased in supply
what is the theory of supply and the determinants of demand
And please what is change in quantity supplied?
guys why are you so quiet
A woman has a television set which cost her $800 two years ago. A new set would cost her $1000 and she could sell her television set for $450. What is the opportunity Cost of keeping the old TV?
Murewah Reply
Maybe the opportunity cost of the TV is 800
principle of effective demand?
Abubakar 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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