成本效益分析与代际公平:新代际折现思路

Cost-benefit Analysis and Intergenerational Equity:A New Intergenerational Discounting Approach

成本效益分析在评价涉及长期资源环境影响的项目和政策时因损害代际公平而颇受批评,因此如何修正成本效益分析使其能够用于这类项目和政策的评价是研究的焦点。本文从可持续发展理论出发,首先比较分析经验代际折现率、零社会折现率、单一环境折现率和双重社会折现率四种当前具有代表性的代际折现率的提出背景、计算方法和运用范围,然后构建基于多重社会折现率的新代际折现思路,最后以水土保持项目为例,利用数字模拟方法验证了新代际折现思路的具体运用。结果表明:其一,与四种当前代表性的代际折现率相比,多重社会折现率在评价具有复杂环境影响的项目和政策上更具优势;其二,基于多重社会折现率的新代际折现思路能够为涉及长期资源环境影响的项目和政策评价提供系统的折现率选择指导;其三,多重社会折现率下的环境折现率遵循随着时间推移递减,随着人造资本与资源环境间替代难度的增大而递减的原则。最后文章从构建多领域专家参与平台和编制折现率查询表两个方面提供政策建议。

Becanse of the harm to intergenerational equity,cost-benefit analysis has been thought of as an invalid instrument for evaluating the projects and policies with long-term impacts on natural resources and environment.It,therefores is a research focus on how to adapt cost-benefit analysis to these projects and policies at present.From the perspective of sustainable development theory,the paper,first,conducts a comparative analysis of the background,calculation methods and application scopes of four sorts of representative intergenerational discount rates including experimentation-oriented intergenerational discount rate,zero social discount rate,unitary environmental discount rate and dual social discount rate.Then it establishes a new intergenerational discounting approach which centers on multi-social discount rate,and last,a new discounting approach is simulated in a numerical simulation way with an example of water and soil conservation project.It is concluded that：①multi-social discount rate is superior to the four sorts of representative intergenerational discount rates in terms of evaluating the projects and policies with long-term and complicated impacts on natural resources and environment;②the new intergenerational discounting approach centered on multi-social discount rate could provide systematic guidance to how to select discount rate in the evaluation process of projects and policies;③each environmental discount rate in the framework of multi-social discount rate must be estimated in accordance with the principle that it decreases in time span and in the difficulty of substitution between man-made capital and environmental resources.The paper ends up with the policy implication of establishing a stakeholder of multi-discipline experts and compiling a discount rate table.