Substitution and income effects and the Law of Demand | APⓇ Microeconomics | Khan Academy

TL;DR

The demand curve slopes downwards due to the substitution effect, income effect, and decreasing marginal utility.

Transcript

• [Narrator] In other videos, we have already talked about the Law of Demand, which tells us, and this is probably already somewhat intuitive for you, that if a certain good is currently at a higher price, that the quantity demanded will be quite low, and then as the price were to decrease, the quantity demanded would increase. So if we were to gra... Read More

Key Insights

• 🚙 The demand curve slopes downwards due to the substitution effect, income effect, and decreasing marginal utility.
• 👋 The substitution effect occurs when the price of a good decreases, leading to increased demand as consumers substitute it for relatively more expensive goods.
• 🥺 The income effect explains that as the price of a good decreases, consumers have more purchasing power, leading to increased demand.

Questions & Answers

Q: Why does the demand curve slope downwards?

The demand curve slopes downwards due to the substitution effect, income effect, and decreasing marginal utility. When the price decreases, consumers substitute the good for other relatively more expensive goods, while the decrease in price also leads to increased purchasing power and demand. Additionally, consumers experience diminishing marginal utility as they consume more of a good.

Q: How does the substitution effect contribute to the downward-sloping demand curve?

The substitution effect occurs when the price of a good decreases, making it relatively more attractive compared to other goods. Consumers may choose to substitute the relatively cheaper good for others, leading to an increase in demand for that good.

Q: What is the income effect and its impact on the demand curve?

The income effect suggests that when the price of a good decreases, consumers have more disposable income. This increase in purchasing power allows consumers to buy more of the good, leading to an increase in demand.

Q: What is decreasing marginal utility and its role in the demand curve?

Decreasing marginal utility refers to the diminishing satisfaction or value consumers derive from consuming additional units of a good. As consumers already satisfy their initial craving, the marginal utility of each additional unit of the good decreases. This contributes to the downward-sloping demand curve.

Summary & Key Takeaways

• The Law of Demand states that as the price of a good increases, the quantity demanded decreases, and vice versa.

• The substitution effect explains that as the price of a good decreases, consumers are more likely to substitute it for other goods that are now relatively more expensive.

• The income effect suggests that as the price of a good decreases, consumers have more purchasing power and may choose to buy more of that good.

• Decreasing marginal utility is another reason for the downward-sloping demand curve, as consumers derive less satisfaction from each additional unit of a good consumed.