mr. gorbachev, tear down this wall! but the historians say this did more to end the cold war. >> finally, we're all thought that politics changed history, but larry flynn historians say that politicians, as important. >> that's our show tonight. >> and now, john stossel. >> what built the middle class? unions, i'm told, but union leaders often tell me when i confront them about bad things that unions do, we built the middle class they say. here is the head of wisconsin's firefighters union. the middle class would not be where it is today without the unions. >> the unions claim they helped minorities. a sample of my interview with the head of new york city's 3400 member transit union. >> you discount the extremely positive impact that the trade union has had in this country launching people into the middle class, particularly african-americans and latinos, but that's just not true say tom woods and damon root. woods is the author of "33 questions about american history you're not supposed to ask" damon root writes for reason magazine. both have studied history and shocked how much of what they learned in school turned out to be wrong, like what? >> well