For over a century, the Democratic Party has embraced the idea of progress. While the old progressivism focused almost exclusively on economics, the new progressivism has expanded its demands to cover everything from on-demand contraception to same-sex marriage. Progressive claims about the inevitability of progress are, however, increasingly undermined not only by the costs of progressive policies, but also by opposition from conservative Republicans. What are the principles and virtues that move each party? How will they stand up to events?