Warren professor of American history James T. Kloppenberg, a specialist in the intellectual history of the United States and Europe and now chair of the history department, observed the 2008 presidential election from afar: he was teaching at the University of Cambridge. As he lectured on the U.S. political tradition and studied Barack Obama’s writings, he began to see three strong, but unexamined, themes. The first is Obama’s sophisticated understanding of America’s history and its continuing democratic experiment. The second is the idea of pragmatism—America’s principal contribution to Western philosophy—which was first elaborated by William James and John Dewey, themselves...