It is hard to imagine a world in which acts like the murders of James Foley and Steven Sotloff simply as Americans, in connection with an American decision to rescue others from imminent annihilation, did not produce among Americans a demand for punishment as both practical and moral necessity. Yet there is a tendency even among many would-be supporters of President Obama, or of his plans to “degrade and ultimately destroy” “the group known as ISIL,” to diminish and disdain politically aggravated homicides as actual and compelling bases for a specifically American reaction.