“Most conspiracy theorists don’t understand this, but if there really were a C.I.A. plot [involving the assassination of President Kennedy], no documents would exist.” — Author Gerald Posner (“Case Closed”) speaking to N.Y. Times reporter Scott Shane in a 10.16 story about whether the Central Intelligence Agency might be “covering up some dark secret” about JFK’s murder? “Probably not,” Shane writes. “But you would not know it from the C.I.A.’s behavior.”