Material needs may be defined in either absolute or relative terms. Absolute material needs are those that are universal, or fixed, for everyone in the population, while relative material needs are those that may vary depending on circumstances or norms (Ravallion, 1994).(2)
Based on research in developing countries, some analysts argue that there is an "irreducible core" (Sen, 1979) of absolute basic needs that are closely linked (theoretically and empirically) to a physiological interpretation of those things that are vital to human survival: "minimum specified quantities of such things as food, clothing, shelter, water, and sanitation that are necessary to prevent ill-health, undernourishment and the like" (Streeten, 1981, p. 25).
In contrast, relative needs are those "things that established rules of decency have rendered necessary" ([Adam] Smith, 1776, quoted in Sen, 1979, p. 288). In this case, the standard of need may vary depending on two factors social wealth and context. As a society gets "richer" the relative standard of need changes to reflect societal wealth. For example, 75 years ago no one would have considered a telephone to be a necessity. However, today, given the almost universal access to telephones and the important role access to a telephone plays in people's ability to function in daily life, it could be argued that not having a telephone is a material hardship. Needs also are contextual. Basic needs or a minimum living standard might vary by region of the country or urban versus rural settings. Even for an absolute material need such as food, a threshold may be set in relative terms, far above the physiological minimum but corresponding to a view as to what people "should" have.
Despite the benefits of a relative standard of need that reflects social wealth and context, it could be argued that defining need in absolute or near-absolute terms has several advantages.
- An absolute standard is more likely to remain relevant across individuals, time and place;
- Measures that assess whether people meet their very basic material needs may be more easily linked to short- and long-term outcomes; and,
- People are less likely to voluntarily forego opportunities to meet their very basic needs, which means that these needs are more likely to be universally applicable (Beverly, 1999b).