City Journal's Ben Boychuk and Philadelphia Magazine's Joel Mathis talk to historian Richard Immerman about his latest book, "Empire for Liberty: A History of American Imperialism from Benjamin Franklin to Paul Wolfowitz."

Summary: City Journal's Ben Boychuk and Philadelphia Magazine's Joel Mathis talk to historian Richard Immerman about his latest book, "Empire for Liberty: A History of American Imperialism from Benjamin Franklin to Paul Wolfowitz."