I'm almost done reading Drew Westen's excellent The Political Brain. Short version: The enlightenment ideal of a rational mind (and, hence, a rational voter) is complete poppycock. Republicans know this and use it to beat the stuffing out of Democrats, who are distrustful of emotional appeals. There is nothing wrong, however, with making an emotional appeal. Republicans tend to make unprincipled emotional appeals (i.e. lying about their opponents record to getcha all riled up), Democrats need to make principled emotional appeals.