美国的不平等程度正处于近一个世纪以来的最高点。不管你如何解读,收入最高的人群正享用着更大的一块蛋糕;位于贫困线以下的人群正在扩大,中值收入和最高收入人群之间的差距也在拉大。美国曾经认为自己是一个中产阶级国家,但情况已不再是这样了。经济学家们引用“边际生产率理论”(Marginal productivity theory)为此类差异提供理由,该理论用更大的社会贡献来解释更高的收入。但那些提供推动技术进步的 The level of inequality in the United States is at the highest point in nearly a century. No matter how you interpret, the highest-paid people are enjoying a bigger piece of cake; the population below the poverty line is expanding and the gap between the median and the highest income groups is widening. The United States once considered itself a middle-class country, but the situation is no longer the case. Economists cite Marginal productivity theory for reasons of such discrepancies, which explain greater income with greater social contribution. But those who provide the impetus for technological progress