Scarcity and Choice
FoundationWants are unlimited but resources are limited — scarcity is the root of economic problems. Scarcity forces choices, every choice carries an opportunity cost, and hence free goods, economic goods and the three basic economic questions.
- Scarcity is the root of economic problems: unlimited wants, limited resources — a relative concept
- Free goods and economic goods are distinguished by scarcity, not by price tags
- Scarcity forces choice, and every choice has an opportunity cost — the highest-valued option forgone
文體小知識：經濟現象說明文——解釋稀少性、選擇與機會成本的因果關係，並以香港日常資源分配現象加以說明。
§Text Passage
1The root of economic problems is scarcity: human wants are unlimited while resources are limited. Even the wealthiest society lacks the resources to satisfy every want. In Hong Kong, time, land and money are all limited: a student's study hours after school are not enough for every subject, and public funds cannot meet every demand for infrastructure and welfare at once. Scarcity is a relative concept — resources are insufficient relative to wants — and it is a basic fact every society faces.
2Goods fall into two categories: free goods and economic goods. A free good is so abundant that even at a zero price it would not fall short of demand; enjoying it requires giving up nothing, so it carries no opportunity cost. An economic good is insufficient relative to wants, so obtaining it involves a sacrifice. The test is not whether a price tag exists: the free tea a restaurant serves is an economic good paid for by the business, while fresh air in the country parks, enjoyed by everyone at no charge, is a free good.
3Scarcity forces individuals, firms and the government to make choices, and every choice involves an opportunity cost — the highest-valued option forgone. Society likewise faces the three basic economic questions: what to produce, how to produce, and for whom to produce. Different societies handle them differently: some by custom and tradition, some by government decision, while market economies such as Hong Kong rely mainly on the market mechanism, with prices steering resources.
4Production possibilities make scarcity visible: an economy's resources are limited, so producing more of one good means producing less of another. Take Hong Kong land: more plots used for housing means less kept as country parks or farmland — the two move in opposite directions. Such trade-offs show that every choice by society has a cost, and economics is precisely the study of how people choose under scarcity.
1Summary 重點摘要
Wants are unlimited but resources are limited — scarcity is the root of economic problems. Scarcity forces choices, every choice carries an opportunity cost, and hence free goods, economic goods and the three basic economic questions.
2Vocabulary cards Vocabulary
Wants are unlimited while resources are limited, so goods cannot satisfy all wants — the root of economic problems.
Human wants keep arising and can never be fully satisfied — one cause of scarcity.
Resources such as land, labour and capital are insufficient relative to wants — the other cause of scarcity.
A good so abundant that even at a zero price it would not fall short; consuming it involves no opportunity cost.
A good insufficient relative to wants; obtaining it requires giving up something else.
Under scarcity, people must decide which uses get the resources and which wants are satisfied.
The highest-valued option forgone when a choice is made — the cost of choosing.
What to produce? How to produce? For whom to produce? — the questions every society must answer.
The mechanism that allocates resources through prices: goods go to those willing and able to pay.
3Step by step Steps
- Step 1: What scarcity meansScarcity means wants are unlimited while resources are limited: people always want more than they can get, and this is the root of economic problems. Note that scarcity is relative — not that resources are absolutely few, but that they are insufficient relative to wants. For example, a millionaire's wealth seems endless, yet a day has only 24 hours, so time is scarce for the rich too. Hong Kong's income per head is among the world's highest, yet land and housing remain short and property prices stay high — even a wealthy society cannot escape scarcity.
- Step 2: Free goods and economic goodsGoods are classified by scarcity. A free good is so abundant that even at a zero price it would not fall short of demand; enjoying it requires no sacrifice. An economic good is insufficient, so obtaining it has a cost. Judge by opportunity cost, not by whether a price is charged. For example, the complimentary soup at a tea restaurant is an economic good that costs the business money, while fresh air in the country parks — free to all and never in shortage — is a free good.
- Step 3: Scarcity forces choiceBecause resources are insufficient, not all wants can be met at once; individuals, firms and the government must choose which wants to satisfy and which to give up. For example, an S4 student has three hours after school: studying mathematics means less time for piano practice. If the government allocates more resources to public housing, spending on other projects may have to be cut. Choice is everywhere, from daily life to public policy — and that is where economics begins.
- Step 4: The cost of choice is opportunity costEvery choice has a cost. Opportunity cost is the highest-valued option forgone when a choice is made — not the sum of all forgone options. For example, on Saturday afternoon you could take a part-time job earning $600, join a volunteer service, or rest at home. If you take the job, the opportunity cost is the more valuable of the other two options, not both added together. The next lesson explains the definition and calculation of opportunity cost in detail.
- Step 5: The three basic economic questionsScarcity obliges every society to answer three basic economic questions: what to produce — which goods and services resources go into; how to produce — which methods and technologies to use; and for whom to produce — how output is distributed. For example, whether Hong Kong land goes to housing, commercial towers or country parks is 'what to produce'; building with prefabricated modules or manual labour is 'how'; and the allocation rules for public housing flats are 'for whom'.
- Step 6: How societies handle the three questionsSocieties answer the three questions in different ways: some by social custom and convention, some by government planning and decision, while others rely mainly on the market mechanism, letting prices steer resources. For example, public housing in Hong Kong is allocated by the government through income and asset tests, while private flats are allocated by the market — those willing and able to pay the market price get the units. One society can use several mechanisms side by side for different goods.
- Step 7: Production possibilities and trade-offsProduction possibilities show the combinations of goods an economy can produce when resources are fully used and technology is fixed. Using more resources for one good means less of the other — a trade-off. For example, each extra hectare of land built into housing reduces the land left for farms and country parks; if resources sit idle, actual output falls inside the possible combinations. A production possibilities table condenses scarcity, choice and opportunity cost into one picture.
5Worked example Example
Application: a community has fixed labour and equipment to produce masks or gloves. Four production combinations are: A (100 masks, 0 gloves), B (90 masks, 40 gloves), C (70 masks, 70 gloves) and D (40 masks, 90 gloves). If the community moves from combination B to C, what is the opportunity cost of producing 30 more pairs of gloves? Which economic concepts does the example illustrate?
- Read the question: labour and equipment are fixed and technology is unchanged, so more of one good means less of the other — scarcity at work
- Compute the gain: moving from B to C, gloves rise from 40 to 70 pairs, an increase of 30 pairs
- Compute the loss: masks fall from 90 to 70, a decrease of 20 — the price of the extra 30 pairs
- State the conclusion: the opportunity cost per extra pair is 20 ÷ 30 ≈ 0.67 masks; scarcity makes every choice costly
- Answer: Moving from combination B to C, the community gains 30 pairs of gloves at the cost of 20 masks, so the opportunity cost of the 30 extra pairs is 20 masks — about 0.67 masks per pair. With fixed resources and unlimited wants, more of one good necessarily means less of the other: this is exactly how scarcity gives rise to choice and opportunity cost, and the production possibilities table displays the trade-off clearly.
6Common mistakes Mistakes
7Quick check Quick check
Q1What is the root of economic problems?
Q2How are free goods distinguished from economic goods?
Q3What are the three basic economic questions?
Q4What is the definition of opportunity cost?
Q5How does the market mechanism handle the 'for whom' question?
8Recap Recap
- Scarcity is the root of economic problems: unlimited wants, limited resources — a relative concept
- Free goods and economic goods are distinguished by scarcity, not by price tags
- Scarcity forces choice, and every choice has an opportunity cost — the highest-valued option forgone
- The three basic economic questions: what, how and for whom to produce
- Societies use custom, government decision or the market mechanism; production possibilities show trade-offs