This article examines sustainability from a policy perspective rooted in environmental economics and environmental ethics. Endorsing the Brundtland Commission stance that each generation should have undiminished opportunity to meet its own needs, I emphasize the foundational status of the intergenerational commitment. The standard concepts of weak and strong sustainability, WS and SS, are sketched and critiqued simply and intuitively, along with the more recent concept of WS-plus. A recently proposed model of a society dependent on a renewable but vulnerable resource (Barfuss et al. 2018) is introduced as an expositional tool, as its authors intended, and used as a platform for thought experiments exploring the role of risk management tools in reducing the need for safety. Key conclusions include: (i) Safety, in this case, the elimination of risk in uncertain production systems, comes at an opportunity cost that is often non-trivial. (ii) Welfare shocks can be cushioned by savings and diversification, which are enhanced by scale. Scale increases with geographic area, diversity of production, organizational complexity, and openness to trade and human migration. (iii) Increasing scale enables enhancement of sustainable welfare via local and regional specialization, and the need for safety and its attendant opportunity costs is reduced. (iv) When generational welfare is stochastic, the intergenerational commitment should not be abandoned but may need to be adapted to uncertainty, e.g., by expecting less from hard-luck generations and correspondingly more from more fortunate ones. (v) Intergenerational commitments must be resolved in the context of intragenerational obligations to each other in the here and now, and compensation of those asked to make sacrifices for sustainability has both ethical and pragmatic virtue. (vi) Finally, the normative domains of sustainability and safety can be distinguished—sustainability always, but safety only when facing daunting threats.

中文翻译：

---

关于代际承诺、弱可持续性和安全性

本文从植根于环境经济学和环境伦理的政策角度审视可持续性。赞同布伦特兰委员会的立场，即每一代人都应该有不受减少的机会来满足自己的需求，我强调代际承诺的基础地位。弱可持续性和强可持续性的标准概念 WS 和 SS，连同最近的 WS-plus 概念，都被简单直观地勾勒和批判。最近提出的依赖可再生但易受攻击的资源的社会模型（Barfuss 等人，2018 年）被引入作为说明工具，正如其作者的意图，并用作思想实验的平台，探索风险管理工具在减少风险方面的作用安全的需要。主要结论包括： (i) 安全，在这种情况下，消除不确定生产系统中的风险，往往需要付出不小的机会成本。(ii) 储蓄和多样化可以缓冲福利冲击，而储蓄和多样化可以通过规模得到加强。规模随着地理区域、生产多样性、组织复杂性以及对贸易和人口迁移的开放程度而增加。(iii) 扩大规模可以通过地方和区域专业化提高可持续福利，减少对安全的需求及其伴随的机会成本。(iv) 当代际福利是随机的时，不应放弃代际承诺，而可能需要适应不确定性，例如，对倒霉的一代期望得少，而对幸运的一代期望得更多。(v) 代际承诺必须在此时此地的代内义务的背景下得到解决，对那些被要求为可持续发展做出牺牲的人的补偿具有道德和务实的优点。(vi) 最后，可以区分可持续性和安全性的规范领域——可持续性总是存在的，但只有在面临令人生畏的威胁时才安全。