Other things being equal (that is, the Ceteris Paribus assumption)

Emphasizing the Ceteris paribus assumption when stating the law of demand indicates that “other things are held constant”. This is necessary because price is not the only thing that affects acquisitions. There are many others that affect purchases and income levels of consumers is one of them. Concurrently, if the price of a product is changing and income levels of customers is also changing, it would be difficult to know whether the change in quantity bought is due to a change in the price or to a change in the income. Therefore, income levels of consumers as well as other factors that could affect the quantity of a product bought are held constant except the price of the product under study. In summary, holding all other things equal obviously implies holding prices of other goods, tastes, advertising, etc. constant when stating the law. Implicitly, the concentration is on the price change of the product under study relative to all o…