Define “Terrorism”

Inspired by last week’s remembrances of the attacks on 9/11, I set out to research the prevalence of terrorist attacks in the United States since then. What I learned astonished me. What surprised me was not how common or rare such attacks have been but how controversial the definition of terrorism itself remains.

There is no internationally accepted definition of terrorism. Or, rather, there are lots of definitions—there is no single accepted one.

I would define terrorism as violence or the threat of violence intended to coerce public action by frightening or intimidating a population for a political or ideological objective. That definition has several components: violence or its threat; intimidation extending beyond the immediate victims; an attempt to coerce action; a political or ideological objective; and some question of who or what may legitimately be targeted. Somehow one or more of those components has eluded agreement whenever the international community has tried to define terrorism.

One distinction seems particularly important. Political violence is not necessarily terrorism. Political assassination is not necessarily terrorism. Anti-government violence is not necessarily terrorism. Terrorism is distinguished not merely by the motive of the perpetrator but by the use of violence to intimidate a broader population in order to coerce political action.

I can’t help but wonder whether the reason a definition has eluded us is that a rigorous definition would constrain the parties doing the defining. A definition broad enough to encompass everything one side wants to condemn may also encompass actions by itself or its allies that it considers legitimate.