Books by J.M. Berger
The Berger definition of extremism:
Extremism is the belief that an in-group’s success or survival can never be separated from the need for hostile action against an out-group.
Excerpt from J. M. Berger's Extremism (The MIT Press Essential Knowledge series) (click here to buy):
The in-group is a group of people who share an identity, such as religious, racial, or national. It is the group to which one belongs—the “us” in “us versus them.” The out-group is a group of people who are excluded from a specific in-group. They are part of “them.” [...]
Extremism refers to the belief that an in-group’s success or survival can never be separated from the need for hostile action against an out-group. The hostile action must be part of the in-group’s definition of success. Hostile acts can range from verbal attacks and diminishment to discriminatory behavior, violence, and even genocide. [...]
Extremism can be the province of state or nonstate actors, unlike terrorism, which after years of similar debate and ambiguity, has come to be understood primarily as a nonstate phenomenon. Each component of this definition is important, since not every harmful or violent act is necessarily extremist. Competition according to a set of negotiated rules is not usually extremist, because in-group success (winning) can be separated from harmful, out-of-bounds acts against competitors (such as persecution, sabotage or assassination). This applies to such pursuits as politics, sports, or business. The need for harmful activity must be unconditional and inseparable from the in-group’s understanding of success in order to qualify as extremist.
The call to action is inherent to this definition. For instance, it is not extremist to disapprove of a religion based on its tenets. But it is extremist to demand that all adherents of a religion be arrested or deported.
Finally, the definition is dependent on an assertion of identity. Societies are entitled to craft laws regulating behavior, for instance by establishing a minimum age for marriage, and these rules may conflict with the rules of some group identities. It is not extremist to differ over values. But laws crafted specifically to target an out-group identity—for instance, Jim Crow laws enforcing segregation, or laws restricting religious belief—are extremist under this definition. The question of intent leads to some unavoidable gray areas, but evaluating legal and political decisions against the other components of this definition can help clarify the question in many cases.
Violent extremism is the belief that an in-group’s success or survival can never be separated from the need for violent action against an out-group (as opposed to less harmful acts such as discrimination or shunning). A violent extremist ideology may characterize its violence as defensive, offensive, or preemptive. Here again, inseparability is the key element—a stipulation that the need for violence against an out-group is not conditional or situational. War is not automatically extremist, but a genocidal war is.
Radicalization into extremism is the escalation of an in-group’s extremist orientation in the form of increasingly negative views about an out-group or the endorsement of increasingly hostile and/or violent actions against an out-group. Radicalization is a process of change, not outcome.