Hillary Clinton swiftly disavowed and condemned the bombing of a Republican campaign headquarters in North Carolina. This is exactly what she should have done. Even the slightest delay or hesitation would have been a PR disaster for her because it could be interpreted as sympathy for the miscreant. There is plenty of room for controversy and jawboning in races for political office, but violence is beyond the pale — or should be. Other democracies have witnessed unjust use of power to influence the ballot box, but it is rare in the US. This campaign has descended to the lowest form of name calling and personal abuse. It is already one of the worst in memory. Wrongful acts would shred the last vestiges of civility.