Few areas of economics are as contentious as a study of economic inequality and, in part, this is because at the same time that "equality" is for many a deeply held value about how society should be, "inequality" is a description of how society is. The most straightforward definition of economic inequality is probably "differences among people in their command over economic resources" (although to be useful one must be more specific about which economic resource and how it is measured). In this book, we do not enter the debate on whether society should be economically equal or unequal or how a "just" degree of economic inequality should be defined. Rather, the emphasis here is on description and analysis—description of the extent of economic "inequality" and analysis of its causes. The omission of a full discussion of what "ought to be" is not due to any view that it is an unimportant topic; the omission arises solely because there is more than enough material involved in the description and analysis of economic inequality to fill this, or indeed a much larger, book.
Most people's interest in the extent and causes of inequality stems, however, from the value which they place in "equality." Such a value is traced by many writers to religious roots, that "all men are equal in the eyes of God," since regardless of "superiority in the arts which bring wealth and power, judged by their place in any universal scheme, they are all infinitely great or infinitely small" (Tawney, 1952:38). The value of equality finds expression in such classic statements as the American Declaration of Independence: "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness." "Equality" is thus a very powerful ideal, closely connected to (but not identical with) the criteria of "equity," "fairness," and "justice" by which we judge the moral authority of existing and potential social institutions.