In response to the Islamic State’s execution of American journalist James Foley, President Obama referred to Foley’s killers as a “cancer.” That, of course, implies that anti-American terrorism is like a disease, one that strikes at nations willy nilly, without rhyme or reason. Obama’s cancer metaphor for ISIS brings to mind what President Bush said about al Qaeda after the 9/11 attacks — that the terrorists were motivated by hatred for America’s freedom and values. Under either formulation —...
