What has the left really accomplished over the past two centuries? FDR's New Deal remains one of the great American success stories. In the '60s, leftist politics created a massive countercultural movement -- and sexual and feminist revolutions. The civil rights movement transformed both American society and the American soul. But, if you compare the accomplishments of the American left to those of other parts of the world, like Western Europe, its record is remarkably dismal, with a surprising lack of real political and social impact.

At least, that's the main takeaway from "American Dreamers," a new book by Michael Kazin, professor of history at Georgetown University, which covers nearly 200 years of struggle for civil rights, sexual equality and radical rebellion. His book explores the way the national conversation has been changed by union organizers, gay rights activists and feminists. He also writes about how their techniques have now been adopted by the Tea Party movement. From Michael Moore to "Wall-E," he argues that, although the left has been successful at transforming American culture, when it comes to practical change, it's been woefully unsuccessful.

Salon spoke to Kazin over the phone about the difference between Europe and America, the rise of the professional left -- and why the Lorax is a progressive icon.

In the book, you argue that the left has been very successful at changing American culture -- but not at making real economic or political change. Why?

It's easier to get people to think about things differently than it is to construct institutions that alter the basic building blocks of society. When leftists talk about having a vision of how things might be different, they attract an audience and create a new way of perceiving things. It's a different issue altogether to go up against entrenched structures of wealth and political power. There are few obstacles to talking differently, singing different kinds of songs, or making a different kind of art, but it takes a sustained movement of millions of people to really change the structures, and that is much harder to organize. Also, most Americans accept the basic ground rules of capitalist society. The ideas are that if you work hard you can get ahead and that it's better to be self-employed than employed by the people. They believe that the basics of a capitalist society are just or can be made just with small alterations. Americans want capitalism to work well for everybody, which is somewhat of a contradiction in terms since capitalism is about people competing with each other to get ahead, and everyone's not going to be able to do well at the same time. That's simply not possible....