Utility
The concept of utility is central to neoclassical economics, providing the logical basis for the relationship between demand and price that is used in the law of supply and demand.
Definition
Utility has a precise meaning in economics but that meaning is not easily defined. The utility of an item to a person is a measure of how much he wants it, but it is not a measure that can be expressed as a numerical quantity. How much he wants it can, it is true, be measured as the amount of some other item that he is willing to give in exchange for it, but that amount will depend upon how much of both items he already has. There is, in fact, no logical possibility of a numerical measure of utility. Utility is necessarily an “ordinal measure”. That means that, although a person can rank the utilities that he gets from two different items in order of magnitude, he cannot assign a numerical magnitude to either, and although he is aware that getting more of an item increases his utility, he cannot say by how much. Nor is it logically possible to compare the utility experienced by different persons. Nevertheless the concept of utility has been widely employed in development of economic theory.
Origins and development
The term utility was mentioned by the classical economists but its present-day usage is generally attributed to its derivation towards the end of the nineteenth century by William Stanley Jevons [1]. It was derived independently at about the same time by Alfred Marshall who expounded it in words and in mathematical terms in his Principles of Economics [2] and deduced from it the concept of the demand curve. Those derivations were further developed and extended in the early twentieth century by Francis Edgeworth and Vilfredo Pareto. The theory that emerged has no empirical content, having been derived entirely by verbal and mathematical deduction from introspective postulates, but it has been widely used to construct economic models that have themselves been subject to empirical testing.