Intermediate Microeconomics Without Calculus

Introduction

Intermediate microeconomics explores how individuals, households, and firms make decisions to allocate limited resources. While advanced microeconomics often relies on calculus, the core concepts can be understood through graphical analysis and logical reasoning. This guide covers the fundamental theories of intermediate microeconomics without requiring mathematical derivations.

Consumer Theory

Budget Constraints

A budget constraint represents all combinations of goods a consumer can purchase given their income and prices. It's shown graphically as a downward-sloping line indicating trade-offs between goods. The slope equals the ratio of the two goods' prices, showing how many units of one good must be given up to afford one more unit of the other.

Utility and Indifference Curves

Utility represents consumer satisfaction or happiness from consuming goods. While we can't measure utility directly, we can order preferences - we can say a consumer prefers combination A to B, or is indifferent between them. Indifference curves show all combinations that provide equal satisfaction.

Key properties of indifference curves:

• They are downward-sloping (more of one good must compensate for less of another)
• They are convex to the origin (consumers prefer averaged bundles)
• Higher indifference curves represent higher utility
• They don't intersect

Consumer Optimization

Consumers maximize utility given their budget constraint by reaching the highest possible indifference curve. The optimal choice occurs where the budget constraint is tangent to an indifference curve (they just touch at one point). At this point, the marginal rate of substitution (how willing a consumer is to trade one good for another) equals the price ratio.

Income and Substitution Effects

When the price of a good changes, two effects occur:

1. Substitution Effect: Consumers substitute toward the now relatively cheaper good
2. Income Effect: The change in purchasing power changes consumption

For normal goods, both effects work in the same direction (lower price leads to higher consumption). For inferior goods, they work in opposite directions (lower price increases purchasing power, potentially decreasing consumption of inferior goods). Giffen goods are a rare case where the income effect outweighs the substitution effect, causing demand to move opposite to price changes.

Producer Theory

Production and Costs

Production functions show the maximum output possible given inputs. The short run has at least one fixed input, while all inputs are variable in the long run. Key concepts include:

• Marginal Product: Additional output from one more unit of input
• Diminishing Returns: Eventually, adding more of an input increases output by smaller amounts
• Fixed Costs: Costs that don't vary with output
• Variable Costs: Costs that change with output level
• Marginal Cost: Cost of producing one more unit

Profit Maximization

Firms maximize profit where marginal revenue equals marginal cost (MR=MC). For perfectly competitive firms, price equals marginal revenue, so they produce where P=MC. Profit is total revenue minus total cost, represented graphically as the area between price and average cost at the optimal output level.

Producer Surplus

Producer surplus is the difference between what producers receive and the minimum amount they would be willing to accept. It's the area above the supply curve and below the market price.

Market Structures

Perfect Competition

Perfect competition requires many small buyers and sellers, homogeneous products, perfect information, and free entry and exit. The demand curve for each firm is horizontal (perfectly elastic), with firms as price takers. In the long run, economic profits are zero as entry eliminates any above-normal returns.

Monopoly

A monopoly has a single seller facing the market demand curve. The profit-maximizing output occurs where marginal revenue equals marginal cost. Since marginal revenue is below demand (the monopolist must lower price on all units to sell more), the monopoly price exceeds the competitive price, creating deadweight loss.

Oligopoly

Oligopoly features a few firms interacting strategically. Key models include:

• Cournot Model: Firms simultaneously choose quantities
• Bertrand Model: Firms simultaneously choose prices
• Stackelberg Model: Sequential quantity leadership
• Kinked Demand Curve: Explains price rigidity

Monopolistic Competition

Monopolistic competition combines elements of monopoly and perfect competition. Many firms sell differentiated products, giving each some market power (similar to monopoly). However, free entry drives economic profits to zero in the long run (as in perfect competition).

Game Theory

Basic Concepts

Game theory analyzes strategic interactions where outcomes depend on choices made by multiple decision-makers. Key elements include:

• Players: Decision-makers in the game
• Strategies: Possible actions available to players
• Payoffs: Outcomes resulting from strategy combinations

Nash Equilibrium

A Nash equilibrium occurs when each player's strategy is optimal given the strategies of all other players. No player can benefit by unilaterally changing their strategy.

General Equilibrium

Partial equilibrium examines a single market in isolation, while general equilibrium considers simultaneous equilibrium in all markets. The Edgeworth Box model illustrates exchange between two consumers with fixed endowments of two goods. Key concepts include:

• Pareto Efficiency: No one can be made better off without making someone worse off
• Contract Curve: All points of tangency between indifference curves
• Core: Allocations that no coalition can improve upon

The First Welfare Theorem states that competitive equilibria are Pareto efficient. The Second Welfare Theorem suggests that any Pareto efficient allocation can be achieved through competitive markets with appropriate redistribution.

Market Failures

Externalities

An externality occurs when a transaction affects third parties not directly involved. Negative externalities (pollution) result in overproduction; positive externalities (education) result in underproduction relative to social optimum. Solutions include:

• Pigouvian taxes/subsidies
• Regulation
• Creating property rights (Coase Theorem)

Public Goods

Public goods are non-excludable (people cannot be prevented from using them) and non-rivalrous (one person's use doesn't reduce availability). markets typically underprovide public goods due to free-rider problems, requiring government provision or funding.

Factor Markets

Labor Markets

Labor demand is derived from the marginal revenue product of labor (additional revenue from one more worker). Labor supply depends on the trade-off between income and leisure. Equilibrium wages are determined by the intersection of labor demand and supply.

Capital Markets

Firms demand capital to maximize profits, weighing current costs against future benefits. Intertemporal choice models explain savings and investment decisions across time periods. Interest rates serve as prices that coordinate intertemporal trade.