Inequality, Bipolarization, and Tax Progressivity
评估了旨在减少收入不平等和两极分化的税收制度设计可能性，基于两种不同度量指标，为税收累进性提供了统一基础：累进税当且仅当能减少不平等，而减少不平等的税当且仅当能减少两极分化。
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.