The steady rise in income and wealth inequality in the last four decades, together with the evolution of a vanishing middle class, has raised concerns about potentially pernicious effects of these trends on social stability and economic growth. This paper evaluates the possibility of designing tax systems aimed at reducing income inequality and bipolarization. Using two fundamentally different metrics, we provide a unified foundation of tax progressivity whereby, roughly, taxes are progressive if and only if they are inequality reducing; and taxes are inequality reducing if and only if they are bipolarization reducing. (JEL D31, H22, H24)

中文翻译：

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不平等、两极分化和税收累进

过去 40 年中收入和财富不平等的稳步上升，以及正在消失的中产阶级的演变，引发了人们对这些趋势对社会稳定和经济增长的潜在有害影响的担忧。本文评估了设计旨在减少收入不平等和两极分化的税收制度的可能性。使用两个根本不同的指标，我们提供了税收累进性的统一基础，大致而言，当且仅当税收减少不平等时，税收才是累进​​的；当且仅当税收减少两极分化时，税收才能减少不平等。(JEL D31, H22, H24)