Foundations of Microeconomics

Introduction to Microeconomics What is Microeconomics? Microeconomics is the study of how individuals and firms make decisions about allocating scarce resources. Unlike macroeconomics, which examines total economic activity across an entire economy (growth, inflation, unemployment), microeconomics zooms in to analyze individual markets, specific industries, or particular decision-makers. The core goal of microeconomics is to understand how markets work. Specifically, microeconomics analyzes the market mechanisms that determine prices and allocate resources across the economy. A key question is: when do free markets produce efficient outcomes—where resources are used in the best possible way—and when do they fail? The figure above shows a basic market with supply and demand curves intersecting to determine an equilibrium price and quantity. This type of analysis is central to microeconomics. Market Failure: When Markets Don't Work Well An important concept in microeconomics is market failure, which occurs when markets do not produce efficient outcomes. Market failures are situations where the free market allocates resources inefficiently, meaning resources are wasted or not distributed in the best way possible. Understanding when and why markets fail is crucial because it helps explain when government intervention might be justified. The Connection Between Micro and Macro While microeconomics focuses on individual decision-makers, it has deep connections to macroeconomics. Modern macroeconomic theories are built on microfoundations—they assume that macroeconomic behavior emerges from the rational decision-making of individuals and firms at the micro level. Additionally, microeconomics helps us understand how economic policies affect individual behavior. For example, when a government changes tax rates or regulations, microeconomics allows us to predict how consumers and firms will respond to these changes. These individual responses then aggregate to affect the overall economy that macroeconomists study. Foundations of Microeconomic Analysis Rational Preferences At the heart of microeconomics is an assumption about human behavior: individuals are rational. In economic terms, rationality doesn't mean people are always perfect or knowledgeable. Rather, it means that a person's preferences satisfy three key properties: Stable preferences: An individual's preferences don't change arbitrarily or unexpectedly. Complete preferences: For any two options, a person can always determine whether they prefer one, the other, or like them equally. There are no incomparable options. Transitive preferences: If someone prefers option A to option B, and prefers B to C, then they must prefer A to C. Preferences are internally consistent. These three properties might seem obvious, but they are powerful assumptions. They allow economists to represent preferences mathematically using a utility function—a numerical score representing how much satisfaction a person gets from different choices. For example, if eating 3 apples gives a person utility of 15, while eating 2 apples gives utility of 12, the person prefers 3 apples. There's one additional important assumption: local non-satiation, which means that more of a good is always weakly preferred to less. In other words, people never get so much of something that they'd prefer to have less of it. This captures the intuition that goods are actually desirable—they contribute to well-being. The Utility Maximization Problem Given that people have rational preferences and face a limited budget, the fundamental microeconomic problem is the Utility Maximization Problem (UMP). This is a constrained optimization: A consumer chooses a bundle of goods to maximize their utility, subject to the constraint that they cannot spend more money than they have available. More formally, suppose a consumer has income $I$ and wants to buy goods at given prices. The UMP asks: what combination of goods should they buy to be as satisfied as possible without exceeding their budget? The solution to the UMP—the bundle of goods a consumer actually chooses—is called the Walrasian demand function (or demand correspondence). This tells us, for any given prices and income level, exactly what a rational consumer will buy. Demand functions are central to microeconomics because they describe consumer behavior, and consumer behavior drives markets. <extrainfo> An Alternative View: Revealed Preference Theory While the utility maximization framework is the dominant approach in microeconomics, there is an alternative foundation called revealed preference theory. Rather than starting with the assumption that people have utility functions and maximize them, revealed preference theory takes actual consumer choices as the primitive starting point. The theory then asks: what can we infer about people's preferences from observing their choices? This approach is intellectually satisfying because it avoids making assumptions about unobservable "utility" and instead works directly with observable behavior. However, for an introductory course, the utility-maximization framework is more commonly used. </extrainfo>