Basic Economic Concepts: Utility, Value, Price, Wealth, Income, Goods and Services

Before the Std XI Economics course moves to money, statistics and applied topics, a few basic terms recur throughout the subject and must be clearly distinguished.

Utility is the want-satisfying power of a good or service — the satisfaction, real or expected, that a consumer gets from consuming it. Two features matter: utility is subjective and relative (the same good gives different satisfaction to different people, or to the same person at different times), and it is ethically neutral (utility is not the same as usefulness or moral approval — a cigarette has utility for a smoker even though it harms health). Total Utility (TU) is the satisfaction from a given quantity consumed, and Marginal Utility (MU) is the additional satisfaction from one more unit, roughly $MU = \dfrac{\Delta TU}{\Delta Q}$.

Value ordinarily means value in exchange — the quantity of other goods or money for which a unit of a good can be exchanged. This differs from value in use, which is another name for utility. The classical paradox of value (the diamond–water paradox) makes the difference sharp: water has enormous value in use (essential to life) but very little value in exchange (cheap and abundant), while diamonds have limited value in use but very high value in exchange (extremely scarce). The explanation lies in scarcity and marginal utility, not total usefulness.

Price is simply value expressed in terms of money — the monetary measure of a good's exchange value, determined in a market economy by the interaction of demand and supply.

Wealth is a stock concept: the material, transferable, scarce goods having money value that a person or a nation owns at a given point in time — land, a house, jewellery, a bank balance, shares.

Income is a flow concept: the earnings, in money or in kind, that a person or a factor of production receives over a period of time (a month, a year) in return for productive services — wages for labour, rent for land, interest for capital, profit for entrepreneurship. When such flows are added up for an entire country over a year, the result is the country's National Income. The key distinction to remember: wealth is a stock measured at a point in time; income is a flow measured over a period of time. …