中文摘要
本文对公共成本收益分析中社会贴现率（SDR）选择问题的相关文献进行了批判性综述。我们讨论了两种主导方法：第一种以市场价格为基础，第二种以跨期伦理为基础。尽管两种方法都各有吸引力，但均非无可置疑。即使市场是完善的，基于市场的方法也并非完全令人信服；一旦认识到市场不完善的影响，该方法还将面临更大的阻力。相比之下，“伦理”方法——将社会贴现率与单一规划者的跨期福利函数所隐含的边际替代率联系起来——并不完全依赖市场，但由此引出一个棘手的问题：该福利函数应当是什么样的。在这一问题上存在相当大的分歧，这种分歧转化为对长期收益评价的巨大差异。我们讨论了这些分歧的根源，并指出它们难以得到明确解决。这促使我们提出第三种方法，承认某些规范性分歧具有不可改变的性质，并提出对多种跨期社会福利理论进行整合的方法。我们说明了这些方法在社会贴现中的应用，并指出它们或许有助于我们超越长期困扰这一领域的争论。（JEL D60、D61、D71、H43、H54）
Abstract
This paper provides a critical review of the literature on choosing social discount rates (SDRs) for public cost-benefit analysis. We discuss two dominant approaches, the first based on market prices and the second based on intertemporal ethics. While both methods have attractive features, neither is immune to criticism. The market-based approach is not entirely persuasive even if markets are perfect, and faces further headwinds once the implications of market imperfections are recognised. By contrast, the ‘ethical’ approach—which relates SDRs to marginal rates of substitution implicit in a single planner’s intertemporal welfare function—does not rely exclusively on markets, but raises difficult questions about what that welfare function should be. There is considerable disagreement on this matter, which translates into enormous variation in the evaluation of long-run payoffs. We discuss the origins of these disagreements, and suggest that they are difficult to resolve unequivocally. This leads us to propose a third approach that recognises the immutable nature of some normative disagreements, and proposes methods for aggregating diverse theories of intertemporal social welfare. We illustrate the application of these methods to social discounting, and suggest that they may help us to move beyond long-standing debates that have bedevilled this field. (JEL D60, D61, D71, H43, H54)