it has been a dizzying period for the white house. in series of interviews, the president hasn t odd answers to questions. he said he would be honored to meet with kim jong-un if the circumstances are right. i would absolutely be honored to do it. he promised something his current plan doesn t consider. pre-existing conditions are in the bill. and he also questioned why he had to have a civil war, the american civil war, the big war 150 years ago. why was there the civil war? why could not one not have been worked out. joining us now the historian at princeton university. and cnn presidential his tor