뒤로Chapter 8: Trade – Microeconomics Study Notes
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Trade
Introduction
This chapter explores the economic principles underlying trade, including the production possibilities curve, comparative and absolute advantage, the gains from specialization, and the effects of trade between individuals, states, and countries. It also examines the arguments for and against free trade, and the impact of trade policies such as tariffs.
The Production Possibilities Curve (PPC)
Definition and Interpretation
The Production Possibilities Curve (PPC) illustrates the maximum possible output combinations of two goods that can be produced with available resources and technology. It demonstrates the concept of opportunity cost and efficiency in resource allocation.
Efficient Points: Points on the PPC represent efficient use of resources.
Inefficient Points: Points inside the PPC indicate underutilization of resources.
Unattainable Points: Points outside the PPC are not possible with current resources.
Opportunity Cost: The slope of the PPC shows the opportunity cost of one good in terms of the other.
Example: If moving from point D to B on the PPC means giving up 4 programs to gain 2 websites, the opportunity cost of 1 website is 2 programs.

Shifts in the PPC
Outward Shift: Indicates economic growth due to more resources, better technology, or higher quality resources.
Inward Shift: Represents a reduction in productive capacity.
The Basis for Trade: Comparative Advantage
Comparative vs. Absolute Advantage
Comparative Advantage: The ability of an economic agent to produce a good at a lower opportunity cost than another agent. Trade is based on comparative, not absolute, advantage.
Absolute Advantage: The ability to produce more of a good with the same resources than another agent.
Specialization according to comparative advantage increases total output.
Opportunity cost comparisons determine who should specialize in which good.
Example Table:
Website Opportunity Cost | Computer Program Opportunity Cost | |
|---|---|---|
You | 2 computer programs | 1/2 website |
Olivia | 1/2 computer program | 2 websites |
The person with the lowest opportunity cost should produce that good.

Gains from Specialization and Trade
When each agent specializes in the good for which they have a comparative advantage, total production increases.
Trade allows both parties to consume beyond their individual PPCs.

Terms of Trade
The terms of trade refer to the rate at which one good is exchanged for another. For mutually beneficial trade, the terms must fall between the opportunity costs of the two agents.
Your minimum price for a program: 1.5 websites
Olivia’s maximum price for a program: 2 websites
Therefore, the terms of trade will be between 1.5 and 2 websites per program.
Trade Between States
Sources of Comparative Advantage
Natural resources
Human-made resources
Technology
Labor skills and experience
Climate
Exports: Goods produced domestically and sold elsewhere. Imports: Goods produced elsewhere and sold domestically.
Example Table: Comparative Advantage Between States
Apricots Opportunity Cost | Bananas Opportunity Cost | |
|---|---|---|
California | 1/5 banana | 5 apricots |
Florida | 8 bananas | 1/8 apricot |
California should produce apricots (lower opportunity cost), Florida should produce bananas.
Trade Between Countries
World Price and Trade Patterns
Trade occurs when the world price differs from the domestic price. If the world price is higher, a country exports; if lower, it imports.
Exporting Nation: Producers gain, consumers lose, but net welfare increases.
Importing Nation: Consumers gain, producers lose, but net welfare increases.
Winners and Losers from Trade
Consumer Surplus: The difference between what consumers are willing to pay and what they actually pay.
Producer Surplus: The difference between the price producers receive and the minimum they would accept.
Trade redistributes surplus but increases total welfare.
Arguments Against Free Trade
Common Arguments
National Security: Over-reliance on imports for critical goods can be risky.
Cultural Concerns: Fear of losing national identity or values.
Environmental Concerns: Free trade may increase pollution in countries with lax standards.
Infant Industry: New industries may need protection until they become competitive.
Local Jobs and Wages: Potential negative effects on domestic employment.
Protectionism and Tariffs
Protectionism: The belief that governments should restrict trade to protect domestic industries.
Tariff: A tax on imported goods, raising their market price and reducing imports.
Tariffs increase producer surplus and government revenue but reduce consumer surplus and create deadweight loss.
Deadweight Loss from Tariffs
Deadweight loss represents the lost gains from trade due to market distortions like tariffs.
Evidence-Based Economics: Trade and Employment
Trade and Job Loss
Some workers may lose jobs due to trade, but overall, there is no systematic evidence that trade harms workers broadly.
Winners from trade can, in theory, compensate the losers.
Example Problem: New England Textile Industry
Initial equilibrium price: $15, quantity: 15 million units.
World price: $5 (due to imports from China).
Tariff: $5 per million units.
Employment: 10 workers per million units produced.
Trade reduces domestic production and employment but increases consumer surplus.
Summary: Trade increases overall economic welfare by allowing specialization according to comparative advantage, but it also creates winners and losers. Policy debates focus on how to address the negative impacts on those who lose from trade.