Runners at the start of the 117th Boston Marathon. Stew Milne / AP

 

It was a report of the now numbingly familiar sort. Witnesses at the synagogue in Paris recounted that an Iranian immigrant had been screaming “Allahu Akbar!” while he chased the rabbi and his son. When he finally caught up, he slashed away at them with a box-cutter, causing severe lacerations. Nevertheless, the Associated Press assured readers that “[a]n official investigation was underway to determine a possible motive.”

Quite a mystery, that.

It is necessary to search for some “possible” motive because to notice the actual and perfectly obvious mo ...