中文摘要
经济不平等可能影响广泛的社会结果，例如犯罪率、经济增长和政治极化。本文讨论如何在福利主义框架中对此类效应进行建模。我们的主要建议是将经济不平等本身视为一种外部性，这对经典经济理论具有广泛影响。我们通过Mirrlees（1971）最优非线性所得税模型阐明这一点，其中我们聚焦于税后收入不平等外部性。最优最高边际税率尤其受到这种外部性的影响，这为最优最高税率设计引入了一个新的平等维度。我们提出，不平等的外部性属性对最优最高税率的影响可能比常规的财政收入考量更大；因此，我们的模型为现实中政府那些在标准最优税收模型下看似不合理的税收选择提供了理论依据。我们还表明，当前美国税制所隐含的总体不平等厌恶程度不足以同时容纳随收入增加而递减的社会福利权重，以及对不平等外部性效应的显著关切。
Abstract
Economic inequality may affect a wide range of societal outcomes, for example crime rates, economic growth, and political polarization. In this paper we discuss how to model such effects in welfarist frameworks. Our main suggestion is to treat economic inequality itself as an externality, which has wide-ranging implications for classical economic theory. We show this through the Mirrlees (1971) optimal non-linear income taxation model, where we focus on a post-tax income inequality externality. Optimal top marginal tax rates are particularly affected by the externality, implying a novel equality dimension to optimal top tax rate design. We propose that inequality’s externality properties may have larger optimal top tax rate implications than standard revenue concerns; our model thus provides a theoretical basis for real-world governmental tax choices that seem irrational under standard optimal taxation models. We also show that the total inequality aversion implied by the current U.S. tax system is insufficient to accommodate both social welfare weights that are decreasing in income and a significant concern for inequality’s externality effects.