Traditionally, economists and tax theorists justify taxation by means of externalities. In recent years, both scholars and policymakers have begun advocating ‘sin taxes’ on goods whose consumption causes ‘internalities’: unaccounted-for costs that a person imposes on herself, not on others. In this paper, we argue that sin taxes rest on a static model of individual choice. They retain neoclassical rationality—with its endorsement of stable and context-independent preferences—as a normative benchmark for good, i.e., welfare-increasing choice. We contrast this model with a more dynamic understanding of choice in which preferences are context-dependent, evolving, and open to individual processes of experimentation. Such a dynamic understanding of choice is backed by recent findings in psychology and behavioral economics and is integral to the political economy of John Stuart Mill. Contributing to the most recent literature in behavioral welfare economics, we argue that the reality of dynamic and evolving preferences animates a contractarian perspective on public policy which, in turn, provides strong arguments against the sin-tax agenda and supports preference-neutral tax rules.

传统上，经济学家和税收理论家通过外部性为税收辩护。近年来，学者和政策制定者都已开始倡导对消费引起“内部性”的商品征收“罪恶税”：一个人没有自己承担的成本，而不是别人承担的成本。在本文中，我们认为罪恶税基于个人选择的静态模型。他们保留了新古典理性，并认可了稳定的和与情境无关的偏好，以此作为善良（即增加福利的选择）的规范基准。我们将这种模型与对选择的更动态的理解进行对比，在这种选择中，偏好是与上下文相关的，不断变化的，并且对单个实验过程开放。对选择的这种动态理解得到心理学和行为经济学的最新发现的支持，并且是约翰·斯图尔特·米尔（John Stuart Mill）的政治经济学所不可或缺的。对于行为福利经济学的最新文献，我们认为动态的和不断发展的优惠政策的现实使契约主义对公共政策的观点充满了活力，反过来又为反对罪恶税议程提供了有力的论据，并支持了与优惠政策无关的税收规则。