Living standards have soared during the twentieth century, and economists expect them to continue rising in the decades ahead. Does that mean that we humans can look forward to increasing happiness?

Not necessarily, warns Richard A. Easterlin, an economist at the University of Southern California, in his new book, Growth Triumphant: The Twenty-first Century in Historical Perspective. Easterlin concedes that richer people are more likely to report themselves as being happy than poorer people are. But steady improvements in the American economy have not been accompanied by steady increases in people's self-assessments of their own happiness. "There has been not improvement in average happiness in the United States over almost a half century----a period in which real GDP per capita more than doubled," Easterlin reports.

The explanation for this paradox may be that people become less satisfied over time with a given level of income. In Easterlin's word: "As incomes rise, the aspiration level does too, and the effect of this increase in aspirations is to vitiate the expected growth in happiness due to higher income."

Money can buy happiness, Easterlin seems to be saying, but only if one's amounts get bigger and other people aren't getting more. His analysis helps to explain sociologist Lee Rainwater's finding that Americans' perception of the income "necessary to get along" rose between 1950 and 1986 in the same proportion as actual per capita income. We feel rich if we have more than our neighbors, poor if we have less, and feeling relatively well off is equated with being happy.

Easterlin's findings, challenge psychologist Abraham Maslow's "hierarchy of wants" as a reliable guide to future human motivation.

Maslow suggested that as people's basic material wants are satisfied they seek to achieve nonmaterial or spiritual goals. But Easterlin's evidence points to the persistence of materialism.

"Despite a general level of affluence never before realized in the history of the world." Easterlin observes, "Material concerns in the wealthiest nations today are as pressing as ever and the pursuit of material need as intense." The evidence suggests there is no evolution toward higher order goals. Rather, each step upward on the ladder of economic development merely stimulates new economic desires that lead the chase ever onward. Economists are accustomed to deflating the money value of national income by the average level of prices to obtain "real" income. The process here is similar----real income is being deflated by rising material aspiration, in this case to yield essentially constant subjective economic well-being. While it would be pleasant to envisage a world free from the pressure of material want, a more realistic projection, based on the evidence, is of a world in which generation after generation thinks it needs only another 10% to 20% more income to be perfectly happy.

Needs are limited, but not greeds. Science has developed no cure for envy, so our wealth boosts our happiness only briefly while shrinking that of our neighbors. Thus the outlook for the future is gloomy in Easterlin's view.

"The future, then, to which the epoch of modern economic growth is leading is one of never ending economic growth, a world in which ever growing abundance is matched by ever rising aspirations, a world in which cultural difference is leveled in the constant race to achieve the goods life of material plenty, it is a world founded on belief in science and the power of rational inquiry and in the ultimate capacity of humanity to shape its own destiny. The irony is that in this last respect the lesson of history appears to be otherwise: that there is no choice. In the end, the triumph of economic growth is not a triumph of humanity over material wants; rather, it is the triumph of material wants over humanity."

人们的生活水平在20世纪飞速提高，经济学家预计在未来的几十年里，人们的生活水平还会进一步提高。这是否意味着我们人类的日子有望越过越幸福呢？

未必如此，南加州大学一位经济学家理查德?A?伊斯特林在其新书《增长的胜利：从历史的视角展望21世纪》中如是告诫世人。他承认，一般来说，富人比穷人更有可能称自己是幸福的。然而，美国人对幸福感的自我评价并未伴随着美国经济稳步发展而有所提高。伊斯特林指出：“过去近半个世纪中，美国的实际人均国内生产总值增加了2倍多，而人们并未感到比以往更幸福。”

对于这种自相矛盾的现象也许可作如下解释，随着时间的推移，人们对一定的收入会越来越不满。用伊斯特林的话来说：“收入增加了，人们的期望值也相应提高了，期望值的提高会抵消收入提高所带来的预期有所增加的幸福感。”

伊斯特林似乎在说，金钱可以买来幸福，但这只有在自己金钱不断增多，而别人收入不变的情况才会如此。他的分析有助于人们理解社会学家李?雷恩沃特的调查结果----从1950年到1986年，在美国持收入“必须维持基本生活”观念的人随着实际人均收入的增加而同比增长。如果收入比邻居多，我们就会感到自己富有；反之，则觉得自己贫穷。由此可见，人们把幸福感与相对富裕程度等同起来。

伊斯特林的调查结果向心理理学家亚伯拉罕?马斯洛的“需要等级体系”理论提出了挑战，该理论为人类未来的动机提供了可靠指南。马斯洛认为：一旦人们的基本物质需求得到满足后，就会转而追求更高层次的精神需求。但伊斯特林的论证却指出人类的物欲永无止境。

伊斯特林还评述到：“尽管人类历史上从未实现过普遍水平的富裕，但今日最富有的那些国家对物质的关注还是那么迫切，对物质需要的追求还是那样的强烈。”这表明人类并未朝更高层次的精神目标进展。更确切地说，经济发展每上一个台阶只会刺激新的经济需求，进而促进经济持续向前发展。经济学家通常用国民收入的货币价值减去平均物价上涨额度来计算“实际”收入。同样，人们日益增长的物质欲望，在此主要是持续不断对经济富裕的主观要求，削减了实际收入。虽然设想一个没有物欲压力的世界是件惬意的事，但一个基于事实的更为现实的想法是设想在这样一个世界里，世世代代的人们都认为只要将收入再提高10%--- -20%，就可达到无比幸福的境界。

需求是有极限的，而贪欲却无止境。科学再进步也尚未研制出治疗嫉妒的良药，因此只有当我们的财富让邻居相形见绌的时候，我们才会感到片刻的幸福。所以在伊斯特林看来，未来的前景不容乐观：“当今经济发展的趋势告诉我们，未来经济会不断发展、永不停歇，未来世界会是一个财富不断增长而欲望节节上升的世界；一个为达到富裕不断角逐而导致文化差异尽失的世界；一个建立在信仰科学和智力并相信人类有最大的能力塑造自己命运的世界。具有讽刺意味的是，在最后一点上，历史的经验教训似乎告诉我们事物的发展并非如此：人类别无选择，并不能掌握自己的命运。最后，经济发展的结果不是人性战胜物欲，而是物欲战胜人性。”