In the aftermath of the deadly explosions in Boston, one word quickly became attached to the tragedy: terrorism. The major media honed in on the presence of the term in President Barack Obama’s speeches, and as the investigation continues into the motives of its unknown culprit or culprits, so too will speculation into the terrorist pathologies underlying it all. In post–9/11 America, terrorism is the frame through which we now instinctively make sense of seemingly senseless violence.

My colleague Michael Scherer has a good post on the semantic gymnastics terrorism has been put through by the Beltway’s political classes. But, for some scholars, the usage of the term deserves a far deeper historical reckoning. “In the decade that has past, the concept terrorism carries with it an assumption of understanding a danger even before we know what it is, as is the case in Boston,” says Martin A. Miller, a professor of history at Duke University. Miller is the author of The Foundations of Modern Terrorism: State, Society and the Dynamics of Political Violence, a recent book that charts the evolution of terrorism from the French Revolution into its current incarnation of al-Qaeda’s insurgents and CIA drones....