Of all of the questions Hillary Clinton will evade on the campaign trail this week, none are more important than those she will not answer on Iraq. Clinton holds the unique distinction in the 2016 field of having supported the unpopular Iraq policies of both George W. Bush and Barack Obama. She supported Bush’s invasion and Obama’s withdrawal, and in both cases was tracking with public opinion when she started. After Bush’s war got unpopular, Clinton recanted. And one supposes that as Obama’s policy for that woe-begotten nation and its region continues to displease voters, Clinton will be tempted to...