International institutions are facing a new paradox: there is an urgent need for them, but they are increasingly being resisted, and one of the main grounds for supporting and resisting international institutions is their legitimacy. Every organization claims legitimacy for itself and denies the legitimacy of others. However, a framework for evaluating legitimacy is lacking. This paper defines the concept of legitimacy for international institutions and suggests that it derives from four sources (normative values, comparative benefits, national recognition, and confirmation by other international institutions). Based on their relevancy and their capacity for operationalization in this evaluation, indicators for input, operation, and output legitimacy have been selected to methodically evaluate the legitimacy of international institutions.

国际机构面临新的悖论：人们迫切需要它们，但它们却日益受到抵制，而支持和抵制国际机构的主要理由之一就是其合法性。每个组织都声称自己的合法性并否认其他组织的合法性。然而，缺乏评估合法性的框架。本文定义了国际机构的合法性概念，并提出其源自四个来源（规范价值、比较利益、国家认可和其他国际机构的确认）。根据评估的相关性和可操作性，选择了投入、运作和产出合法性指标，系统地评估国际机构的合法性。