Terrorism seems like the kind of thing that has existed since the beginning of states some 5,000 years ago. Understood in one, narrow way–as what we call “insurgency”–it probably has. But modern terrorism is, well, modern as Martin A. Miller explains in The Foundations of Modern Terrorism: State, Society, and the Dynamics of Political Violence (Cambridge University Press, 2013). Miller traces our kind of terrorism to the French Revolution or thereabouts, and specifically to the formation of the idea that “citizens” have a right (and indeed duty) to rebel against their wayward governments “by any means necessary.” Take that notion and another–that there are several different “legitimate” ways to organize governments–and you have modern terrorism: campaigns designed to change or overthrow governments that are deemed by political radicals to be acting illegitimately or to be wholly illegitimate.