中文摘要
政治经济学文献大多将低效政策归咎于制度或政治家供给劣质政策的动机，但选民自身可能也需对需求劣质政策承担部分责任。本文提出，选民在评估潜在政策变动时可能出现系统性偏差，原因在于其低估了新政策如何引致新的均衡行为。这使得选民偏向于那些能产生直接收益的政策变动——若行为保持不变，福利将会上升——即使这些改革最终因人们调整行为而降低了福利。相反，选民对施加直接成本的政策存在偏见而予以反对，即使这些政策能引致更大的间接收益。通过实验室实验，我们发现多数被试投票反对那些虽施加直接成本，但有助于其克服社会困境从而增加福利的政策。被试也支持那些虽产生直接收益，但会引发社会困境并最终损害福利的政策。这两种误判均源于被试未能完全预期新政策的均衡效应。更确切地说，我们证实被试系统性地低估政策变动影响他人行为的程度，且这些错误信念对劣质政策的需求产生了因果效应。
Abstract
Most of the political economy literature blames inefficient policies on institutions or politicians’ motives to supply bad policy, but voters may themselves be partially responsible by demanding bad policy. In this article, we posit that voters may systematically err when assessing potential changes in policy by underappreciating how new policies lead to new equilibrium behaviour. This biases voters towards policy changes that create direct benefits—welfare would rise if behaviour were held constant—even if those reforms ultimately reduce welfare because people adjust behaviour. Conversely, voters are biased against policies that impose direct costs even if they induce larger indirect benefits. Using a lab experiment, we find that a majority of subjects vote against policies that, while inflicting direct costs, would help them to overcome social dilemmas and thereby increase welfare. Subjects also support policies that, while producing direct benefits, create social dilemmas and ultimately hurt welfare. Both mistakes arise because subjects fail to fully anticipate the equilibrium effects of new policies. More precisely, we establish that subjects systematically underappreciate the extent to which policy changes will affect the behaviour of other people, and that these mistaken beliefs exert a causal effect on the demand for bad policy.