摘要： 近年来，美国正在发生一场具有深远历史影响的大变局，这一变局的基本逻辑是美国政治正在从过去一百年来的进步主义周期，进入到一个保守主义的周期，它不仅深刻影响美国，而且深刻影响世界。面对这一大变局，既有研究更多基于国家视角和制度主义路径，无法解释美国大变局的历史动因和底层逻辑。事实上，美国大变局是世界百年未有之大变局的一部分，美国的国家体系及其制度框架没有发生本质性变化，但美国赖以立足的生态体系和社会基础已经发生了根本性变化，有必要确立生态制度主义的视角进行分析。从生态制度主义视角看，美国大变局导致美国在国内和国际维度都发生了深刻的历史转型：在国内社会，美国越来越成为一个建制主义与反建制主义二元竞争的国家；在国际社会，美国越来越成为一个全球主义与本土主义二元竞争的霸权。无论是国内转型还是国际转型，美国大变局的根源在性质上均基于身份政治逻辑，这一逻辑将驱动一个新美国的诞生。

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Abstract: In recent years, a profound transformation with far-reaching historical implications is unfolding in the United States. The fundamental logic of this transformation is that American politics is breaking away from the progressive cycle of the past century and embarking on a conservative cycle. This transformation not only has a profound impact on the United States itself but also on the world at large. In fact, the profound transformation in the United States is part of the unprecedented global changes in the past century. While there have been no essential changes in the U.S. national system and its institutional framework, the ecological system and social foundation on which the United States stands have undergone fundamental changes. From the perspective of ecological institutionalism, the major transformation in the United States has led to profound historical transitions both domestically and internationally: domestically, the United States is increasingly becoming a country marked by a binary competition between institutionalism and anti-institutionalism; internationally, it is increasingly becoming a hegemon characterized by a binary competition between globalism and nativism. Whether it is the domestic or international transition, the root causes of the profound transformation in the United States are fundamentally based on the logic of identity politics, which will drive the emergence of a new America.

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