What we’re seeing here is how three structural changes that have been building in American politics have now, together, reached a tipping point — creating a world in which a small minority in Congress can not only hold up their own party but the whole government. And this is the really scary part: The lawmakers doing this can do so with high confidence that they personally will not be politically punished, and may, in fact, be rewarded. When extremists feel that insulated from playing by the traditional rules of our system, if we do not defend those rules — namely majority rule and the fact that if you don’t like a policy passed by Congress, signed by the president and affirmed by the Supreme Court then you have to go out and win an election to overturn it; you can’t just put a fiscal gun to the country’s head — then our democracy is imperiled.