The social nature of economics

Economics is a social science that studies how individuals and societies make choices when allocating scarce resources to satisfy needs and wants. Its social character comes from its focus on human behaviour. Households, firms, governments and other decision-makers interact, respond to incentives and affect each other.

The choices they make shape economic well-being—people's material security, their ability to meet needs and their freedom to make economic choices. Impersonal forces don't produce economic outcomes on their own. Institutions, values, politics, history, psychology and the natural environment all play a part. Economists may therefore reach different conclusions about the same issue because human motivations vary and people don't value outcomes in the same way.

Economies don't stand still. Preferences, technology, institutions, resources and relationships change over time, so economists often study the causes and consequences of change rather than treating an economy as fixed. Decisions are also interdependent. A firm's choice may affect workers' incomes, consumers' choices, government tax revenue and conditions in other countries.

To make this complexity manageable, economists use models. Each model deliberately removes some detail, allowing an important relationship to be studied more clearly. That simplification is useful, but any conclusion must be interpreted in light of the model's assumptions.

Microeconomics and macroeconomics

Microeconomics is a branch of economics that studies individual economic decision-makers, particular markets and specific industries. For example, it may examine a household's spending choices, a firm's output decision or the price of a particular service.

Macroeconomics is a branch of economics that studies the economy as a whole through aggregate outcomes. Its focus includes economy-wide production, unemployment, inflation, economic growth and the effects of national policy.

These are different levels of analysis, not separate worlds. When many individuals change their decisions, the combined effect can produce a macroeconomic outcome. In turn, an economy-wide development may change the choices available to every household and firm. This is interdependence in action.

The nine central concepts

The nine concepts appear throughout the course. Treat them as connected ideas, rather than a stand-alone vocabulary list.

• Scarcity is a condition in which limited resources are insufficient to satisfy all human needs and wants. It is the central economic problem.
• Choice is a decision between competing alternatives that is required because scarcity prevents every option from being selected.
• Efficiency is a condition in which resources are used without avoidable waste to achieve the greatest possible output or satisfaction. It concerns how effectively resources are used, but doesn't tell us whether the outcome is fair.
• Equity is a normative principle concerning the perceived fairness of economic outcomes and opportunities. It is not the same as equality. An equal outcome may still be viewed as unfair, while people may defend an unequal outcome as fair.
• Economic well-being is a condition describing people's material living standards, financial security and ability to meet needs and make meaningful economic choices. Current well-being matters, as does the ability to maintain it.
• Sustainability is a condition in which present activity meets current needs without undermining the resources and environmental systems available to future generations.
• Change is a process in which economic conditions, behaviour, institutions or relationships move from one state to another over time.
• Interdependence is a relationship in which the choices or outcomes of one economic decision-maker affect those of others. The effects can cross markets and national borders, sometimes unintentionally.
• Intervention is deliberate action by a government or another authority that changes market behaviour or outcomes. It may aim to improve efficiency, equity, well-being or sustainability. Whether intervention improves outcomes—and how extensive it should be—remains debated.

These concepts can pull in different directions. Economic growth may improve current well-being while increasing resource depletion. An outcome can be highly efficient yet still be judged inequitable, and a government intervention designed to fix one problem may cause another. Continued growth based on ever-greater use of finite resources cannot last indefinitely. This has led to debate over whether prosperity should be measured only through expanding output or should give more weight to resilience, distribution and long-term environmental limits.

Factors of production

Factors of production are productive resources used to create goods and services. Economists group them into four categories:

• Land is a factor of production consisting of natural resources used in production. This covers physical land and water, as well as forests, minerals and energy resources. Some of these resources are renewable. Others are finite or regenerate only very slowly.
• Labour is a factor of production consisting of human physical and mental effort used in production. Both its quantity and quality depend partly on the population's health, education and skills.
• Capital is a factor of production consisting of human-made resources used to produce other goods and services. Examples include machinery, tools, buildings and infrastructure. Money itself doesn't count as capital in this sense.
• Entrepreneurship is a factor of production consisting of the organization of the other factors, decision-making, innovation and the bearing of business risk. The entrepreneur chooses how to combine resources and accepts the uncertainty surrounding the outcome.

Each factor contributes to production and has alternative uses. Take a skilled engineer working on public transport: the engineer cannot spend the same working time developing renewable-energy equipment. That alternative use makes the allocation decision economically significant.

Scarcity, wants and sustainability

Human needs and wants are effectively unlimited. Once people satisfy some of them, they can identify others or look for higher quality and greater variety. Resources, however, are limited at any particular time. A need is a requirement regarded as essential for an acceptable standard of living, whereas a want is a desire for a good, service or experience that is not required for basic survival. The boundary varies between places and over time, but needs and wants both make claims on scarce resources.

Scarcity doesn't mean that a resource is almost completely absent. Rather, the available quantity cannot satisfy every possible use at a zero price. Even a prosperous society faces scarcity, so it must decide how to allocate land, labour, capital and entrepreneurship.

These choices also affect future generations. Using a non-renewable resource today leaves less for the future, while pollution may weaken the natural systems that later production will depend on. Sustainability asks, “What can we produce now?” It also asks, “What productive possibilities are we leaving to those who follow?” Output cannot keep increasing indefinitely if it relies on ever-greater consumption of finite resources.

Opportunity cost and free goods

A genuine choice always involves a sacrifice. Opportunity cost is the value of the next best alternative forgone when a choice is made. The words “next best” matter: opportunity cost isn't the total of every option rejected. Suppose a government builds a hospital on a site rather than using it for the best alternative, a housing development. The opportunity cost is the value of the housing development forgone.

An economic good is a good or service that uses scarce resources and therefore has an opportunity cost. Most goods and services fit this definition, even if users aren't charged directly. A publicly provided library service still requires land, labour and capital, for example.

A free good is a good that is sufficiently abundant relative to demand that obtaining it requires no sacrifice of an alternative use and therefore carries no opportunity cost. Whether the label applies depends on the circumstances. Clean air might seem freely available in one setting but become scarce elsewhere if maintaining air quality requires resources. “Free of charge” is not the same as “a free good” — keep that distinction sharp.

The basic economic questions

Resources cannot satisfy every want, so every society must answer three questions:

1. What and how much should be produced? This asks which goods and services should receive resources, and in what quantities.
2. How should production take place? This deals with production techniques and the combination of factors used, such as labour-intensive versus capital-intensive methods.
3. For whom should output be produced? This asks who receives the goods, services and income produced.

The answers affect relative well-being. A society might produce more healthcare instead of luxury consumption, choose a cleaner but more costly production process, or redistribute access to education. Each option brings benefits, costs and trade-offs for different groups.

Markets, government and economic systems

A market is an arrangement through which buyers and sellers interact to exchange goods, services or factors of production. Prices and profits guide resources towards certain uses and away from others. Governments can influence allocation through laws, taxation, spending, public ownership or regulation. In practice, policy debates usually focus on the right balance between markets and government rather than an absolute choice between them.

A free market economy is an economic system in which factors of production are predominantly privately owned and market forces largely determine resource allocation. Consumer spending, along with firms' responses to prices, helps decide what is produced and in what quantities. Firms select production methods. Purchasing power has a strong influence on who receives the output.

A planned economy is an economic system in which the state owns or controls most productive resources and central authorities make the principal allocation decisions. A planning authority determines output priorities and production methods, as well as the distribution of many goods and services.

A mixed economy is an economic system in which private markets and government intervention both allocate resources. Actual modern economies follow this model, though the degree and form of intervention differ. One country may depend more heavily on markets; another may provide more goods publicly or regulate production more extensively.

No method of allocation removes scarcity. It changes how choices are made, whose preferences carry the most weight and how opportunity costs are distributed.

Purpose and assumptions of the model

A production possibilities curve is a model showing the maximum combinations of two goods or categories of goods that an economy can produce in a given period when its available resources are fully employed and used efficiently. The usual abbreviation is PPC.

The basic model assumes:

• only two goods, or two broad categories of output, are considered;
• the quantity and quality of factors of production are fixed;
• technology is fixed;
• the period under consideration is fixed; and
• resources on the curve are fully employed and used productively efficiently.

Of course, the real world does not literally contain only two goods, nor does technology remain unchanged. These assumptions simply isolate the trade-off caused by scarcity.

Scarcity, choice and opportunity cost on a PPC

Any point on the PPC is both attainable and productively efficient. The economy cannot increase production of one good without cutting production of the other. Since several combinations on the curve are possible, scarcity forces a choice. The downward slope shows the opportunity cost: moving right produces more of the horizontal-axis good while sacrificing some of the vertical-axis good.

A point inside the PPC is attainable, but productively inefficient, because resources are unemployed or poorly used. By contrast, a point outside the PPC cannot be reached with current resources and technology. The picture should be read quickly: a point on the curve shows maximum current output, one inside shows spare capacity, while one outside lies beyond current capacity.

The diagram brings these ideas together. Points A and B are efficient choices because they lie on the PPC. A move from A to B gains units of consumer goods but sacrifices units of environmental services; those sacrificed services are the opportunity cost. Point U, inside the curve, shows unemployment or inefficient resource use. Point Z is outside current production possibilities.

Increasing and constant opportunity cost

A bowed-out PPC represents increasing opportunity cost. Equal additional amounts of one good require progressively larger sacrifices of the other. Resources are specialized, so they are not equally well suited to every use. When production shifts toward one good, the resources best suited to that good move first. Later, the economy must transfer resources increasingly better suited to producing the other good.

A straight-line PPC represents constant opportunity cost. Here, each equal additional amount of one good requires the same sacrifice of the other. Resources are equally adaptable between the two uses, so the slope stays constant.

The geometry needs to be precise. A PPC bowed outward from the origin becomes steeper as production moves to the right, showing an increasing opportunity cost for the horizontal-axis good. A straight line shows a constant trade-off.

Unemployment, efficiency and actual growth

Productive efficiency is a condition in which an economy produces the maximum possible output from its available resources and technology. Every point on the PPC is productively efficient. However, that point may not be equitable, sustainable or the combination society most wants.

Unemployed labour, idle factories or poor organization can leave production inside the PPC. Once previously idle resources begin producing, the economy moves from an interior point toward the existing curve. Actual economic growth is an increase in current output represented by movement from a point inside a PPC toward the curve. Productive capacity hasn’t necessarily increased; the economy is simply using its existing capacity more fully.

Growth in production possibilities

Growth in production possibilities is an increase in an economy's maximum productive capacity represented by an outward shift of its PPC. This may come from a larger or better-educated labour force, additional capital or the discovery of natural resources. Stronger institutions and improved technology can also cause it. In the other direction, a loss of resources, destruction of capital or deterioration in technology can shift the curve inward.

Don’t confuse movement toward a fixed curve with a shift of the curve itself. Movement toward the curve is actual growth caused by reduced unemployment or inefficiency. A shift represents growth in production possibilities due to an increase in the quantity or quality of resources, or improved technology.

The shift doesn’t have to be parallel. If a technological improvement benefits only one industry, the PPC rotates outward more strongly toward that good's axis. Growth also raises a question about sustainability. Productive capacity may expand, yet growth that depletes finite resources or degrades natural systems may weaken future possibilities instead of securing lasting prosperity.

The circular flow of income

The circular flow of income is an economic model showing the interdependent real and monetary flows between decision-makers in an economy. In its simplest form, it links households with firms. The fuller model brings in government, banks and the financial sector, as well as the foreign sector.

Households are economic decision-makers that own factors of production, consume goods and services and make decisions about work, saving and spending. They provide firms with land, labour, capital and entrepreneurship. In exchange, households receive factor income: rent, wages, interest and profit.

Firms are economic decision-makers that employ factors of production to produce goods and services. They pay incomes to households, then earn revenue when their output is bought by households, government or foreign buyers.

Two kinds of flow move in opposite directions:

• A real flow is a movement of factors of production or goods and services between economic decision-makers. Households provide factor services to firms; firms provide households with goods and services.
• A monetary flow is a movement of payments between economic decision-makers. Firms pay incomes to households, while households direct consumption expenditure back to firms.

Across the whole economy, total output has the same value as total income and expenditure. These are three records of the same circular activity. Production by firms generates incomes, while spending on that production provides firms with revenue.

Government, finance and the foreign sector

The government sector is the part of the circular flow that collects taxes, purchases goods and services, provides public services and makes transfer payments. Government choices influence household disposable income and firms' sales. They also affect how resources are allocated.

The banks and financial sector are institutions that channel funds between savers and borrowers and facilitate payments. Household saving may fund firms' investment. Lending also lets expenditure take place at a different time from the income that ultimately supports it, linking present choices with future production and consumption.

The foreign sector is the part of the circular flow consisting of foreign households, firms and institutions that trade or make financial transactions with the domestic economy. Domestic residents purchase imports; foreign buyers purchase domestic exports. So an economy is interdependent both internally and with producers and consumers elsewhere.

The full circular-flow diagram maps the links between these sectors, including the points where spending enters or leaves the domestic flow.

Leakages and injections

A leakage is a withdrawal of income from the domestic circular flow of expenditure. There are three main leakages:

• saving, since some current household income isn't spent on consumption;
• taxation, which transfers income to government; and
• imports, where spending goes to foreign producers.

An injection is expenditure added to the domestic circular flow from a source other than household consumption. The three main injections are:

• investment, which means firms' expenditure on capital goods;
• government spending on goods and services produced domestically; and
• exports, meaning foreign expenditure on domestic output.

Savings don't disappear. Taxes aren't necessarily destroyed, and imports aren't inherently harmful. “Leakage” simply describes a flow leaving the core domestic expenditure stream. Savings can return as investment, taxes can fund government spending, and foreign demand can bring expenditure back through exports.

When total injections exceed total leakages, expenditure reaching domestic firms tends to rise. Current output may then expand if spare capacity exists. If leakages exceed injections, expenditure tends to fall. When the two are equal, these flows alone give the circular flow no net tendency to expand or contract.

Interdependence and choice

The circular flow reveals the social nature of economics. If a household saves more, current consumption falls, but those funds may finance investment. When a firm invests, it creates demand for capital goods and may increase future productive capacity. Through taxation and spending, government redistributes purchasing power and redirects resources. Decisions to import create income for foreign firms, while foreign demand supports domestic production.

Feedback effects can follow. Lower household spending cuts firms' revenue. Firms may respond by reducing production and employment, which lowers household income further. In the other direction, stronger export demand can increase firms' revenue, employment and household consumption. No major decision-maker stands alone — that is precisely what interdependence means.