What extremism is, how extremist ideologies are constructed, and why extremism can escalate into violence.

A rising tide of extremist movements threaten to destabilize civil societies around the globe. It has never been more important to understand extremism, yet the dictionary definition―a logical starting point in a search for understanding―tells us only that extremism is “the quality or state of being extreme.” In this volume in the MIT Press Essential Knowledge series, J. M. Berger offers a nuanced introduction to extremist movements, explaining what extremism is, how extremist ideologies are constructed, and why extremism can escalate into violence. Berger shows that although the ideological content of extremist movements varies widely, there are common structural elements.

Berger, an expert on extremist movements and terrorism, explains that extremism arises from a perception of “us versus them,” intensified by the conviction that the success of “us” is inseparable from hostile acts against “them.” Extremism differs from ordinary unpleasantness―run-of-the-mill hatred and racism―by its sweeping rationalization of an insistence on violence. Berger illustrates his argument with case studies and examples from around the world and throughout history, from the destruction of Carthage by the Romans―often called “the first genocide”―to the apocalyptic jihadism of Al Qaeda, America's new “alt-right,” and the anti-Semitic conspiracy tract The Protocols of the Elders of Zion. He describes the evolution of identity movements, individual and group radicalization, and more. If we understand the causes of extremism, and the common elements of extremist movements, Berger says, we will be more effective in countering it.

什么是极端主义，极端主义意识形态是如何构建的，以及为什么极端主义会升级为暴力。

不断涌现的极端主义运动有可能破坏全球各地公民社会的稳定。理解极端主义从未像现在这样重要，但字典上的定义--寻找理解的逻辑起点--只告诉我们，极端主义是 "极端的品质或状态"。在麻省理工学院出版社《基本知识》系列的这一卷中，J.M. Berger对极端主义运动进行了细致的介绍，解释了什么是极端主义，极端主义意识形态是如何构建的，以及为什么极端主义会升级为暴力。伯杰表明，尽管极端主义运动的意识形态内容千差万别，但有一些共同的结构要素。

伯杰是研究极端主义运动和恐怖主义的专家，他解释说，极端主义产生于 "我们与他们 "的看法，并因坚信 "我们 "的成功与针对 "他们 "的敌对行为密不可分而变得更加强烈。极端主义与普通的不愉快--普通的仇恨和种族主义--不同的是它对暴力的坚持的全面合理化。伯杰用世界各地和历史上的案例研究和例子来说明他的论点，从罗马人对迦太基的毁灭--通常被称为 "第一次种族灭绝"--到基地组织的世界末日圣战主义、美国的新 "反右派 "和反犹太主义的阴谋小册子《锡安长老的议定书》。他描述了身份运动的演变，个人和团体的激进化，以及更多。伯杰说，如果我们了解极端主义的原因，以及极端主义运动的共同要素，我们就能更有效地反击它。