A large segment of the political left identifies as “progressive,” but what does a belief in progress entail? This short essay, written for a symposium on Jonathan Gienapp’s fascinating new book, Against Constitutional Originalism, takes up that question. It argues that even under a relatively modest or thin conception of progress, a judgment that moral progress has occurred over some period of time entails a judgment that something like social or moral learning has taken place during that time. If that conclusion is right, it has implications for how we ought to think about social change and the conditions under which it occurs. Since some of the most important Founders also believed in moral progress, it may have implications for constitutional originalism as well.