The law of diminishing marginal utility states that as a person consumes more units of a specific product, the extra satisfaction gained from each new unit decreases.
Key points:
- The first unit usually provides the most satisfaction.
- Each extra unit provides less additional joy or benefit than the one before it.
- Eventually, the total satisfaction may stop growing (zero utility) or even become harmful (negative utility).
Why it happens:
- People use the first few units to satisfy their most urgent needs.
- As more units are consumed, the needs being met become less important.
Example:
If you eat chocolate, the first bar is very satisfying. The second bar is good, but less exciting. By the fifth bar, you might feel full or sick, meaning the satisfaction from that extra bar has dropped to zero or below.
Why it matters in economics:
- It explains why the demand curve slopes downward: people only want to buy more of something if the price drops to match the lower satisfaction they get from extra units.
- It helps explain why consumers choose to buy a variety of goods rather than just one type of product.
- It is the foundation for understanding consumer surplus, which represents the value consumers get beyond what they actually pay.