Understanding the Law of Demand Conditions

The law of demand is a fundamental concept in economics that describes the relationship between the price of a good or service and the quantity consumers are willing to buy. It states that, generally, as the price of a product increases, the quantity demanded by consumers decreases, and conversely, as the price decreases, the quantity demanded increases. This inverse relationship is often visualized using a downward-sloping demand curve.

However, this law operates under a crucial assumption known as ceteris paribus, which is Latin for "all other things being equal." This means that for the law of demand to hold true, various other factors that can influence demand must remain unchanged. Let's analyze the given options to see which condition satisfies this requirement.

Analysis of Options

Option 1: Prices of Related Goods Are Allowed to Change

The prices of related goods (like substitutes and complements) are important determinants of demand. If the price of a substitute good decreases, consumers might switch to that cheaper alternative, reducing the demand for the original good, even if its own price hasn't changed. Similarly, changes in the price of a complementary good affect the demand for the primary good. Since the law of demand assumes these factors are constant, allowing them to change means the law might not hold as expected.

Option 2: Tastes and Preferences of Consumers Are Not Constant

Consumer tastes and preferences significantly influence demand. If consumer preferences shift towards a particular good (e.g., due to trends or advertising), the demand for that good will increase, regardless of its price. Conversely, a decline in preference leads to decreased demand. The law of demand requires that these tastes and preferences remain stable; otherwise, observed changes in quantity demanded could be due to shifting preferences rather than price changes.

Option 3: Own Price of the Commodity Is Assumed to Be Constant

This option contradicts the core principle of the law of demand. The law specifically examines how the quantity demanded responds to changes in the product's own price. If the own price remains constant, we cannot observe or demonstrate the inverse relationship that defines the law of demand.

Option 4: All Determinants of Demand, Other Than Own Price, Remain Constant

This option accurately reflects the ceteris paribus assumption essential for the law of demand. The determinants of demand include factors such as consumer income, prices of related goods, consumer tastes and preferences, consumer expectations, and the number of buyers in the market. The law of demand is valid only when these factors, excluding the commodity's own price, are held constant. This isolation allows economists to clearly attribute changes in quantity demanded solely to changes in the product's price.

Conclusion: The Condition for the Law of Demand

The law of demand holds true when the ceteris paribus condition is met. This means that all factors influencing demand, except for the good's own price, must remain constant. Option 4 correctly identifies this crucial condition, ensuring that the observed relationship between price and quantity demanded is a direct consequence of price changes alone, not external influences.