By now it should be clear that economists are model builders. In the previous reading, we examined one of their most fundamental models, the model of demand and supply. And as we have seen, models begin with simplifying assumptions and then find the implications that can then be compared to real-world observations as a test of the model’s usefulness. In the model of demand and supply, we assumed the existence of a demand curve and a supply curve, as well as their respective negative and positive slopes. That simple model yielded some very powerful implications about how markets work, but we can delve even more deeply to explore the underpinnings of demand and supply. In this reading, we examine the theory of the consumer as a way of understanding where consumer demand curves originate. In a subsequent reading, the origins of the supply curve are sought in presenting the theory of the firm.

This reading is organized as follows:

Section 2 describes consumer choice theory in more detail.

Section 3 introduces utility theory, a building block of consumer choice theory that provides a quantitative model for a consumer’s preferences and tastes.

Section 4 surveys budget constraints and opportunity sets. Section 5 covers the determination of the consumer’s bundle of goods and how that may change in response to changes in income and prices.

Section 6 examines substitution and income effects for different types of goods.