I.1.1. The Necessity-Luxury Continuum
Despite confusions, researchers across all disciplines share a basic understanding of luxury. To begin with, luxury is defined as something that is more than necessary (e.g. by Bearden and Etzel 1982, p. 184; Mühlmann 1975, p. 69; Reith and Meyer 2003, p. 10; Sombart 1922, p. 85).
In contrast to necessity, some authors also characterize luxury by non-necessity and superfluity (e.g. by De Barnier et al. 2006, p. 5; Dubois et al. 2001, p. 15; Csaba 2008, p. 3; Geerts and Veg 2010, p. 2; Jäckel and Kochhan 2000, p. 75).
The distinction between necessity and luxury is based on the availability or exclusivity of resources. While necessities are possessed by virtually everyone, luxuries are available exclusively to only a few people or at least only on rare occasions (Bearden and Etzel 1982, p. 184).
Bearden and Etzel (1982, p. 186) imagined the necessity-luxury dimension as a continuum ranging from absolute necessity to absolute luxury. Accordingly, they developed a six-point Likert scale ranging from "a necessity for everyone’" to "a luxury for everyone" in order to measure the luxuriousness of a number of product categories (see also Kemp 1998, p. 594).
The Necessity Luxury Continuum
Today however, people spend the biggest portion of their income on goods that satisfy more than their necessary or basic human needs, but most of these goods might still not be considered a luxury. Therefore, Chaudhuri (1998, p. 158 et seqq.) criticized the necessity-luxury continuum produced by Bearden and Etzel (1982) and measured necessity and luxury as two separate variables on a seven-point agree/disagree scale ("This product is a luxury [necessity] for me.") No significant relationships were found among these variables (p. 163), which supports the approach of these authors. However, there were goods with low ratings on both variables such as cornflakes, frozen dinners, and potato chips, indicating the need for another category of ordinary goods. Bearden and Etzel (1982, p. 186) actually already considered this category, as they defined luxuries "as not needed for ordinary, day-to-day living.’" Instead of subsuming ordinary goods into the necessity category, the scale can also be extended to the necessity-ordinary-luxury scale, which might be more intuitive for today’s consumers.
In very old lexica, luxury is defined as anything that is more than necessary (e.g. Brockhaus 1846, p. 179). After the increase in the standard of living over many social classes in the late 19th century, the definition was further narrowed by luxury being also that which is more than ordinary (e.g. Meyers 1890, p. 1035). Since then, most lexica share the notion of luxury as anything that is more than necessary and ordinary (e.g. Meyers 1995, p. 189).
However, not everything that is neither necessary nor ordinary is a luxury. For instance, most people rarely have moths in their wardrobe, but still do not consider this extraordinary occurrence a luxury. This demonstrates that the characterization of luxury as non-necessary and superfluous can be misleading because luxury is always meant to satisfy some human needs and desires (Berry 1994, p. 4 et seqq.; Geerts and Veg 2010, p. 2; Giacalone 2006, p. 34; Goody 2006, p. 341). Accordingly, luxury is also associated with "dream" (e.g. by Seringhaus 2002, p. 5; Dubois and Paternault 1995, p. 69). While necessary and ordinary goods are also desirable (or required), a study by Kemp (1998, p. 599; 603) points out an essential difference: "similar items [are] more likely to be perceived as a luxury if they [produce] a positive effect for the recipient than if they [relieve] a state of discomfort [… so that luxuries are…] positive instead of negative reinforcements." Therefore, Kemp (1998, p. 592) compares the necessity-luxury continuum with the hierarchy of needs produced by Maslow (1970), which ranges from basic physiological needs such as hunger (necessities) up to needs of self-actualization (luxuries). These facts demonstrate that the luxuriousness of any resource is not only based on its availability, but also on peoples’ desire for it.
Accordingly, the basic definition of luxury may be summarized as follows:
Luxury is anything that is desirable and more than necessary and ordinary.
Luxury usually refers to single items, in which case it is described as qualitative luxury. In contrast, quantitative luxury refers to the profusion of an excessive amount of resources, which are not necessarily luxurious. For instance, this includes lighting a cigar with a handful of matches (Sombart 1922, p. 86).