That the Enlightenment shaped modernity is uncontested. Yet remarkably few historians or philosophers have attempted to trace the process of ideas from the political and social turmoil of the late eighteenth century to the present day. This is precisely what Jonathan Israel now does.

In Democratic Enlightenment, Israel demonstrates that the Enlightenment was an essentially revolutionary process, driven by philosophical debate. The American Revolution and its concerns certainly acted as a major factor in the intellectual ferment that shaped the wider upheaval that followed, but...