The eminent Harvard political philosopher Michael Sandel is Radio 4's "Public Philosopher." Now, as America prepares for its Presidential elections, he and Radio 4 are going on the road in America with a unique mission to lay bare the deeper moral questions bound up in the noisy Romney and Obama campaigns. In this week's programme, Professor Sandel visits the heartland of America's deep south, hosting a public discussion at the University of Dallas in Texas. He challenges ordinary Texans to consider the moral issues raised when it comes to controlling immigration and deciding who should be entitled to citizenship. Texas has a long frontier with Mexico and the issue of immigration divides people sharply. A million people in Texas are "undocumented" living without immigration papers. Many Hispanic voters want immigration to be reformed and President Obama recently outlined initiatives aimed at this base. Mitt Romney, too, is reaching out to Hispanic voters but many in the Tea Party movement pull the Republicans in the other direction. They insist that the border must be closed and deportations must be stepped up. Against this backdrop, our public audience will be asked: "how far should an open society go on accepting outsiders?" Michael Sandel weaves through these issues with the help of philosophers past and present. Producer: Mukul Devichand.