"When I went to graduate school, in the 1950s, that’s what everyone said, that Americans are very unique. Americans are unique because America is unique. America is unique because of a number of reasons, because of frontier experiences (that’s what Turner said), because our absence of feudalism (some other historians pointed out), and that’s the 1950s. But in the 1960s Americans became more self-critic so to speak, because of the war in Vietnam that affected a lot of historians, and made a lot of people started to see American imperialism and aggression, that kind of thing."