Module I·Article II·~11 min read
Rational Decision Making
What Economics Studies
Turn this article into a podcast
Pick voices, format, length — AI generates the audio
Rational Choice
Scarcity forces us to make choices—at every level: from the everyday decisions of an individual to the strategic decisions of governments. But how should this choice be made exactly? Economic science offers the concept of rational choice—a process of systematically comparing benefits and costs with the goal of maximizing net benefit.
Rational choice means that an economic agent (consumer, firm, government):
- Identifies all available alternatives
- Assesses the benefits and costs of each alternative
- Chooses the option with the greatest net benefit (benefits minus costs)
This does not mean that people always act rationally in life—psychological research by Daniel Kahneman and Amos Tversky showed that people systematically deviate from rational behavior (cognitive biases). But the rational choice model remains a powerful analytical tool that helps to understand and predict economic behavior.
Marginal (Incremental) Analysis
One of the most powerful tools of economic thinking is marginal analysis. The word “marginal” in economics means “additional” or “incremental.” Economists state that optimal decisions are made not based on total (aggregate) costs and benefits, but on the additional benefits and costs from each next unit.
Why is the marginal approach so important? Imagine you manage a coffee shop. The question “Should I sell coffee at all?” is not a marginal question. The marginal question is: “Should I sell one more cup of coffee? Should I hire one more barista? Should I extend opening hours by one more hour?” It is precisely these “on the margin” decisions that determine the optimal scale and structure of the business.
Key Concepts
-
Marginal benefit (MB) — the additional benefit gained from producing or consuming one more unit of a good or service. As consumption increases, marginal benefit usually decreases (the law of diminishing marginal utility). The first glass of water on a hot day brings enormous satisfaction. The tenth glass—significantly less.
-
Marginal cost (MC) — the additional costs incurred when producing one more unit of a good or service. As output increases, marginal costs often rise (due to diminishing returns from variable factors).
Decision Rule
The fundamental rule of marginal analysis is ingenious in its simplicity:
- If MB > MC → you should increase the scope of activity (the additional benefit exceeds the additional cost—you “earn” on every additional unit)
- If MB < MC → you should decrease the scope of activity (additional costs exceed the additional benefit—you “lose” on every additional unit)
- If MB = MC → the optimal level is reached (neither increase nor decrease will improve the result)
Example 1: Production Output Decision
A firm produces 50 units of product per day.
- Marginal benefit (additional revenue) from the 51st unit = £18
- Marginal cost (additional cost) of the 51st unit = £22
- Since MC (£22) > MB (£18), the firm should not produce the 51st unit—it will lose £4 on it. Moreover, the firm should check whether it is already producing too much: perhaps the 50th unit was also unprofitable, and the optimal output is lower than 50.
Example 2: Expansion Decision
A firm produces 100 units of product.
- Marginal benefit from the 101st unit = £12
- Marginal cost of the 101st unit = £9
- Since MB (£12) > MC (£9), the firm should increase output—it will earn an additional £3 on the 101st unit. And it should continue increasing output as long as MB equals MC.
Example 3: Airline and Discounts
Imagine the airline “Aeroflot,” which has a Moscow—Sochi flight with 200 seats. One hour before departure, 170 tickets have been sold at an average price of 8,000 rubles. 30 seats remain empty. What is the minimum ticket price that should be set?
From the perspective of marginal analysis, it doesn’t matter how much the aircraft cost, how much fuel for the full flight costs, or what the average cost per passenger is. The aircraft will fly regardless. Marginal costs of an additional passenger are minimal: onboard food (≈300 rubles), baggage handling (≈200 rubles), additional fuel consumption due to passenger weight (≈500 rubles)—about 1,000 rubles total. Therefore, any ticket sold above 1,000 rubles brings additional profit. That’s why airlines often sell tickets “last minute” at a discount—this is not charity but pure marginal logic.
Example 4: Advertising Budget Decision
Coca-Cola spends billions of dollars each year on advertising. How does it determine the optimal advertising budget? Using marginal analysis. Each additional million invested in advertising brings a certain additional revenue (marginal benefit from advertising). As long as this additional revenue exceeds a million (MB > MC), it makes sense to increase the advertising budget. When an additional million in advertising brings precisely one million in additional revenue, the optimum is reached.
In practice, the first advertising campaigns usually bring the most effect (people learn about the product), but each subsequent campaign is less effective (those who wanted to buy have already bought; those who did not want, are unlikely to change their minds because of one more banner). This reflects the law of diminishing marginal benefit.
Everyday Example: Morning Alarm Clock
You need to leave the house at 8:30. Each additional minute in bed:
- Marginal benefit: more sleep, better well-being
- Marginal cost: more rush, risk of being late, stress
The optimal alarm time is where MB = MC. The first extra minutes of sleep are very valuable (if the alarm rings at 6:00, an extra 30 minutes significantly improves well-being). But the closer to 8:30, the higher the “cost” of each additional minute (increasingly frantic rush). The decision is made on the margin—each extra minute is evaluated separately.
Microeconomics and Macroeconomics
Economic science is divided into two main branches, each of which considers economic phenomena at different levels of scale.
Microeconomics
Microeconomics—literally “small-scale economics”—studies the behavior of individual decision-making agents and the functioning of individual markets. It answers questions: how does a consumer decide what to buy? How does a firm determine how much to produce and at what price to sell? How is the price formed in a specific market?
Key topics of microeconomics:
- Theory of supply and demand: how prices are formed for specific goods
- Elasticity: how sensitive demand is to changes in price
- Production and cost theory: how firms minimize costs
- Market structures: competition, monopoly, oligopoly
- Firm behavior: pricing, output volume, investment
Microeconomics helps businesses make specific decisions. For example, when Starbucks decides whether to raise the price of a latte by 50 rubles, this is a purely microeconomic question: how will the number of cups sold change? Will the price increase compensate for the loss of some customers?
Macroeconomics
Macroeconomics—“large-scale economics”—studies the economy as a whole, examining aggregate (collective) indicators. It answers questions: why does the economy grow or decline? What causes inflation? Why does unemployment arise? How does government policy influence the economy?
Key topics of macroeconomics:
- Economic growth: GDP and its dynamics
- Unemployment: its types and causes
- Inflation: increase in the general price level
- Business cycles: ups and downs in economic activity
- Fiscal policy: government spending and taxes
- Monetary policy: interest rates and money supply
- International trade: exchange rates and trade balance
The Relationship Between Micro and Macro
Micro and macroeconomics are not isolated disciplines, but two sides of the same coin. Macroeconomic phenomena result from millions of microeconomic decisions. Understanding this connection is critically important for analyzing economic policy.
Example 1: Rising Energy Prices. In 2022, after the start of the conflict in Ukraine and the imposition of sanctions, natural gas prices in Europe increased 5–10 times. This macroeconomic event affected every individual firm (micro level): bakeries in Germany faced a sharp rise in energy costs, many were forced to raise bread prices or reduce production. BASF chemical plants reduced ammonia output because gas is a key raw material for its production. In aggregate, these millions of microeconomic decisions led to macroeconomic consequences: slowing economic growth in Europe, inflation rising to 10% and above, and increasing unemployment in energy-intensive industries.
Example 2: Central Bank Decisions. When the Bank of Russia raises the key rate (a macroeconomic decision), it affects every business: loans become more expensive, mortgages less affordable, consumers reduce spending, firms postpone investment projects. Each microeconomic effect in aggregate forms the macroeconomic outcome—slowing inflation, but at the cost of slower economic growth.
Positive and Normative Economics
Economists make a fundamental distinction between two types of statements, and understanding this difference is necessary for competent participation in economic discussions.
Positive Statements
Positive statements are objective, factual assertions about "what is" or "what will be." They can be checked with data, observation, and experiments. They do not contain value judgments.
Examples of positive statements:
- “A 10% increase in the minimum wage leads to a 1–3% reduction in youth employment”—can be checked by studying data from countries that raised the minimum wage
- “Inflation in Russia in 2023 was 7.4%”—this is a fact that can be checked from Rosstat data
- “A 20% increase in the cigarette tax will reduce consumption by 8%”—this is a forecast that can be tested after the tax is introduced
- “Doubling the money supply without changing output will double prices”—this is a theoretical statement that can be checked empirically
Normative Statements
Normative statements are value judgments about "what ought to be." They are based on values, beliefs, and preferences. They cannot be proved or disproved with data—only argued.
Examples of normative statements:
- “The government should raise the minimum wage”—depends on what we value more: incomes of low-paid workers or overall employment
- “Taxes on the rich should be higher”—depends on our notions of fairness
- “The state should not interfere in the economy”—reflects ideological preferences
- “Environmental protection is more important than economic growth”—depends on our priorities
Why Is This Distinction Important?
In real economic debates, positive and normative statements are often mixed, which leads to confusion. When a politician says: “We must lower taxes because it will create jobs,” there are two parts: positive (“lowering taxes will create jobs”—can be checked) and normative (“we must do it”—depends on values).
Competent economic analysis requires clear separation: first we ascertain the facts (positive analysis), and then, based on our values, we make recommendations (normative analysis). For example, an economist can objectively establish that raising the minimum wage reduces employment by 2%, but increases the income of those who keep their jobs by 15%. Then society decides if such a compromise is acceptable—and that is a normative question.
Another classic example: Debates on free trade. Positive analysis shows that free trade increases the country’s overall welfare but can hurt certain industries and workers. The normative question: should we open markets even if it leads to job losses in some sectors? Different countries answer this question differently, based on their values and political preferences.
Practical Tasks
Task: Marginal Analysis in Practice
Question: A firm currently produces 50 units of product. Marginal benefit (MB) from the 51st unit = £18. Marginal cost (MC) from the 51st unit = £22. (a) Should the firm increase, decrease, or keep output unchanged? (b) Explain your answer using marginal analysis.
Solution: (a) The firm should decrease the scope of production (or, at the very least, not increase it to 51 units).
(b) Marginal analysis is based on comparing the additional benefit and additional cost. For the 51st unit: MC (£22) > MB (£18). This means the cost of producing the additional unit exceeds its benefit by £4. Producing this unit would reduce overall profit by £4.
A rational firm produces up to the point where MB ≥ MC. Since for the 51st unit MC > MB, the optimal production level is no more than 50 units. The firm should check whether the condition MC > MB also holds for the 50th unit—if so, it should reduce output further, until it reaches the point where MB = MC.
§ Act · what next