Notes on Principles of Economics - Mankiw, 10th Edition

Economics Overview

Questions Addressed in Economics

• What kinds of questions does economics address?

• What are the principles of how people make decisions?

• What are the principles of how people interact?

• What are the principles of how the economy as a whole works?

Scarcity in Economics

• Scarcity: The limited nature of society’s resources.

  • Explanation: Society has limited resources and, therefore, cannot produce all the goods and services people want.

• Economics: The study of how society manages its scarce resources

  • Economists examine:

    • How individuals decide on work, purchases, savings, and investments.

    • How firms determine production levels and workforce hiring.

    • Forces and trends influencing the overall economy: growth in average income, unemployment rates, inflation.

How People Make Decisions

Principles of Decision Making

• Principle 1: People face trade-offs.

• Principle 2: The cost of something is what you give up to get it.

• Principle 3: Rational people think at the margin.

• Principle 4: People respond to incentives.

Principle 1: People Face Trade-Offs

• Explanation: To obtain one thing, another must be sacrificed.

  • Making decisions involves trading off one goal for another:

  • Example 1: Going to a party before an exam leads to less study time.

  • Example 2: More money can be earned by working more hours, reducing leisure time.

  • Example 3: Allocating resources could mean sacrificing environmental protection for consumer goods production.

Example 1A: Society Faces Trade-Offs

• Military expenditure (guns) versus spending on consumer goods (butter) - increased military spending reduces the standard of living.

• Clean environment achieved through pollution regulations may come at the cost of firms' viability.

Example 1B: Efficiency vs. Equality

• Efficiency: Achieving maximum benefits from scarce resources.

• Equality: Fair distribution of economic prosperity among members of society.

• Trade-off: Redistributing income to improve equality can diminish work incentives and shrink the overall economic "pie."

Principle 2: The Cost of Something is What You Give Up to Get It

• Decision making requires comparing costs and benefits of alternatives, considering opportunity costs.

• Opportunity cost: Whatever must be given up to obtain an item.

Example 2: Opportunity Cost

• Going to college for a year includes tuition and foregone earnings as opportunity cost (not room and board).

• Attending a movie: the price of admission plus the value of the time spent.

Principle 3: Rational People Think at the Margin

• Definition: Rational people systematically make the best possible decisions to achieve their goals with the available opportunities by evaluating costs and benefits of marginal changes.

• A marginal change is a small incremental adjustment to a plan of action.

• Compare marginal benefit and marginal cost to inform decisions.

Active Learning 1: Thinking at the Margin

• Scenario A: Hiring a cashier; marginal benefit is $400/week while marginal cost is $300/week, suggesting hiring is beneficial.

• Scenario B: Watching an additional movie incurs no monetary cost but includes an opportunity cost in terms of time spent.

Principle 4: People Respond to Incentives

• Incentive: Anything that encourages a person to act and can lead to unintended consequences.

• Rational decision-making involves evaluating costs and benefits.

• Example: A price increase in consumer goods leads to reduced demand and increased supply.

Example 3: Government Incentives

• Government increasing gasoline tax prompts consumers to seek fuel-efficient vehicles or public transport alternatives.

Active Learning 2: Economic Decisions

• Scenario: Repairing a car transmission after investing $2,000 in repairs raises the question of whether to fix at $1,400.

• Outcome A: Benefit of fixing yields $3,300; thus, repair is recommended.

• Outcome B: Benefit of fixing yields $1,300; thus, repair is not recommended due to costs exceeding benefits.

How People Interact

Principles of Interaction

• Principle 5: Trade can make everyone better off.

• Principle 6: Markets are usually a good way to organize economic activity.

• Principle 7: Governments can sometimes improve market outcomes.

Principle 5: Trade Can Make Everyone Better Off

• Benefits of trade include access to a greater variety of goods at lower costs, leading countries to specialize in their strengths.

Principle 6: Markets as Organizational Mechanisms

• Market: A collection of buyers and sellers interacting to determine the prices and allocation of goods and services.

• A market economy organizes through decentralized decisions made by firms and households, successfully promoting prosperity.

Market Dynamics

• Prices: Set by the interaction of buyers and sellers, reflect the good’s value to buyers and the costs incurred in production.

• Adam Smith’s invisible hand: Guides price adjustments to promote overall societal well-being.

Principle 7: Governments’ Role in Improving Market Outcomes

• Government Functions:

  • Enforcing property rights and maintaining rules essential for a market economy, fostering willingness to produce and invest.

  • Promoting efficiency by avoiding market failures:

  • Externalities: Effects of production or consumption impacting others negatively (e.g., pollution).

  • Market Power: Situations where a single seller or buyer exerts considerable influence over market prices (e.g., monopolies).

  • Promoting equality through tax and welfare policies to redistribute wealth and reduce disparities without assuming government always improves outcomes.

How the Economy as a Whole Works

Principles of Economic Functioning

• Principle 8: A country’s standard of living depends on its ability to produce goods and services.

• Principle 9: Prices rise when the government prints too much money.

• Principle 10: Society faces a short-run trade-off between inflation and unemployment.

Principle 8: Living Standards and Production

• Significant variations in living standards worldwide, exemplified by average incomes: $65,000 in the U.S. versus $5,000 in Nigeria (2019).

• U.S. income growth at 2% annually leads to doubling every 35 years, signifying an eightfold increase in living standards over a century.

• Productivity: The most crucial determinant of living standards, defined as the quantity of goods produced per labor unit.

Principle 9: Inflation and Money Supply

• Inflation: General rise in prices within an economy.

  • High inflation burdens society, necessitating policies to maintain reasonable inflation rates.

• Long-term inflation is generally fueled by excessive money supply growth, diminishing currency value.

Principle 10: Trade-Offs Between Inflation and Unemployment

• In the short run, economic policies can create opposing trends in inflation and unemployment, presenting a persistent trade-off.

Conclusion of Economic Principles

Individual Decision Making

• Individuals face trade-offs among diverse goals.

• Costs of actions are measured by forgone opportunities.

• Rational decision-making compares marginal costs with marginal benefits.

• Behavioral changes arise in response to faced incentives.

Economic Interactions

• Mutual benefits of trade and interdependence.

• Markets generally coordinate economic activity effectively.

• Government actions can improve market outcomes through addressing failures and promoting equity.

Economic Performance

• Productivity determines living standards.

• Growth in money supply correlates with inflation rates.

• Short-run trade-offs exist between inflation and unemployment.