In the history of our diverse country, there have always been differences in viewpoints. That's why our nation's founders came up with the idea of geographic representation, so that such varied viewpoints would be heard.
Extremism isn't so much about ideals, however, as it is about one's willingness to be challenged at all. It exists on both sides of the aisle. It drives campaign fundraising and votes.
Yet, as history proves, it is also a refuge for scoundrels.
Listen to audio link above to hear tales, anecdotes and observations of extremism.