The more than $400 billion Americans donate annually to charitable causes of all kinds, such as houses of worship, universities and efforts to cure cancer, add up to around 2 percent of the economy. The Indiana University Lilly Family School of Philanthropy, the only school of its kind, brings together scholars of sociology, history, economics, religious studies and other disciplines to explore what drives all this giving. In an interview, which has been edited for length and clarity, Lilly School Dean Amir Pasic, explains why he believes public debate over philanthropy is growing and how U.S. giving has begun to change.