A rising tide of extremist movements threatens to destabilize civil societies around the globe. It has never been more important to understand extremism, yet scholars and policy makers can't even define who is an extremist and why. In this volume in the MIT Press Essential Knowledge series, J. M. Berger offers an introduction to extremist movements, explaining what extremism is, how extremist ideologies are constructed, and why extremism can escalate into violence. Available in English, Spanish, Finnish and Chinese. 

"Elegantly written, the book provides a lucid discussion of a contested concept." -- Perspectives on Terrorism

"J.M. Berger wrote a book that everyone has needed for more than a decade. He combines a wealth of experience from research of extremist groups of all types and sizes to develop a useful taxonomy for all - from the beginner to the expert." -- Clint Watts, author of Messing with the Enemy


The Algorithm Wars have ended, and the world has been optimized. Thanks to the System, everything that happens is recorded, liked, commented, shared and analyzed at scale in order to produce nonstop and ever-improving recommendations. It is a world of total information and total freedom… although things tend to go more smoothly when you follow the System’s prompts.

"Berger’s absorbing story skewers reliance on social media... A sharp, gripping story of a bleak future." -- Kirkus Reviews

"Optimal is a brilliant exploration of the implications of ceding our personal responsibility and relying on algorithms to teach us how to live. But more than that, it’s great storytelling." --

"I was hooked from the first chapter - not because it's so deep, but in spite of that. ... In other words, it's fun to read. You barely notice how terrifying the implications are until you're too far in to care - I promise." -- Amazon Vine Voice reviewer


"Jessica Stern and J.M. Berger's new book, 'ISIS,' should be required reading for every politician and policymaker... Their smart, granular analysis is a bracing antidote to both facile dismissals and wild exaggerations... a nuanced and readable account of the ideological and organizational origins of the group." -- Washington Post 


The definitive book on Americans who joined jihadist movements from the 1970s through 2011. 

"Berger lifts the veil on the phenomenon of American jihadists in this timely and chilling examination." -- Publisher's Weekly

"A sober, factual account of the Americans who have been lured to the cause of religious violence, offers a useful reminder that this phenomenon is nothing new, long predating the Sept. 11 attacks."  -- New York Times

"This is an good and comprehensive overview of the Americans who have fought overseas and within our borders for the cause of intentional jihadism. Berger sheds light on people and stories - especially from the early years immediately after the Soviet invasion of Afghanistan and the US covert support for the mujaheddin - that many likely never knew or hoped were never written about." -- Amazon Vine Voice reviewer