It is the nature of conspiracy theories to turn tragedy into grist, to transform grief and human suffering into an abstract game. The latest horrifying example came out of news late July that Barack Obama’s chef Tafari Campbell had drowned in the waters off Martha’s Vineyard. What was a terrible accident and a tragic loss for Campbell’s family and friends was almost immediately seized upon by the paranoid corners of the internet as proof that somehow Barack and Michelle Obama had been involved in an assassination. It was not the first time that conspiracists have seized on a senseless death...