“A middle-aged man driving a car in Dijon, France, mowed down more than a dozen pedestrians within 30 minutes, occasionally shouting Islamic slogans from his window. The chief prosecutor in Dijon described the attacks, which left 13 injured but no one dead, as the work of a mentally unbalanced man whose motivations were vague and “hardly coherent.” That was a year and a half ago. After last week’s horrific Nice attack, leading politicians immediately called the incident a terror attack. All this brings up a complex question examined by the NYT: In the Age of ISIS, Who’s a Terrorist, and Who’s Simply Deranged?

+ Fusion: How to volunteer to fight ISIS in Syria, in eight steps.