It is commonplace to hear fanaticism described as a deviant or extreme variant of an already irrational set of religious beliefs, an assertion that helps to demonize convictions outside political orthodoxy.

Alberto Toscano’s compelling and erudite counter-history explodes this accepted convention by exploring the critical role fanaticism played in the formation of modern politics and the liberal state. Showing how fanaticism results from a failure to formulate an adequate emancipatory politics, this illuminating history sheds new light on an idea that continues to dominate debates about faith and secularism. This expanded edition includes new material that revisits the idea of fanaticism as it operates at the limits of the liberal political imaginary, highlighting its relation to fraternal violence, political purity and the refusal of compromise, as well as its centrality to times of social crisis and international conflict.