Investopedia defines a normal good as one that “experiences an increase in quantity demanded” when there is an increase in the income of an individual. Inferior goods, on the other hand, are commodities that experience a decrease in quantity demanded when there is an increase in an individual’s income or an improvement in the general economy of a country. An example of an inferior good is public transportation – when an individual’s income increases, they will perhaps want to perhaps invest in a car, instead of using public means of transportation. The car then is an example of a normal good.

Depending on the income levels of different individuals, what is a normal commodity to one person may, in fact, be an inferior commodity to another. Also, what may have been a normal good a few years ago may be inferior today. Thus the terms “normal” and “inferior” are relative terms. For instance, a few years ago, CRT television sets were normal goods to most people all over the world. However, with the development of various types of flat screen television sets, today they are an inferior good to most people.

No, it is not possible for a good to be both normal and inferior.  These are two categories that are opposites of one another so it is completely impossible to be both at once.  Let us see why this is so.

The definition of an inferior good is that changes in the demand for this good are inversely related to changes in consumers’ incomes.  That is, when the consumers’ incomes rise, demand for these goods falls and when consumers’ incomes fall, demand for these goods rises.  We can imagine that something like instant ramen noodles would fall in this category, with people buying more of them as their incomes fell.  If their incomes rose, they would tend to want better things and demand would fall.

The definition of a normal good is that changes in demand are directly related to changes in consumers’ incomes.  That is, when consumers’ incomes rise, so does demand for the product.  Most products are like this.  The more money we have, the more of a product we can afford and therefore the more we buy. 

As you can see, these two definitions are mutually exclusive.  If consumers’ income goes up, demand for a good cannot go up (normal good) and down (inferior good) at the same time.  Therefore, a good cannot be both normal and inferior.