How "Progressive" Is Progressivism?

How “Progressive” is Progressivism? Is there actually a “side of history,” or is that just the lazy formula of presumptive socialists who think they have a monopoly on the truth and don’t need to argue with or persuade anyone? In another of Steve Hayward’s lecture series for the William F. Buckley Jr. Program at Yale, Steve walks through more of the details of Progressivism then and now... Source