What does it really take to change and reform a city or even a country? What kind of person can get the job done? We’ll look back at one such figure this hour with Wendell E. Pritchett, professor of law at the University of Pennsylvania and director of the Office of Research, Planning and Policy for the City of Philadelphia. His new book is “Robert Clifton Weaver and the American City: The Life and Times of an Urban Reformer” (University of Chicago Press, 2008).