Background and purpose: The post-modern approach in the field of international law saw its previous epistemology in a cognitive crisis and claimed that the foundations of the previous methods were damaged. The purpose of this article is to investigate the validation of the fluidity of international law with an emphasis on the ideas of postmodernism.
Materials and methods: This article is descriptive and analytical. Materials and data are also qualitative and data collection was used in collecting materials and data.
Ethical considerations: In this article, the originality of the texts, honesty and trustworthiness are observed.
Findings: Postmodernism in international law is considered a negative school, according to the interpretation that it does not seek to create a conceptual and operational system in the field of law, and as a result, a unified and regular functional system cannot be obtained. But in any case, this procedure is used in the process of legal arguments, and this application has led to the adjustment of many extreme theories in different legal schools.
Conclusion: The limited use of post-modernism as a criticism of some of the current rules of the international law system leads to the emergence of a school called legal pluralism, and according to this, international law emphasizes cultural diversity from the point of view of post-modernism.