Extremist groups like ISIS and al-Qaeda are unable to accept an imperfect society. By force, ISIS would bring in its conception of the perfect society, the Caliphate. The followers of ISIS believe their perfect knowledge justifies killing innocents to attain power.

Less extreme versions exist in democratic societies. My brand of politics isn’t just better than your brand—your brand is a threat to democracy. Only my brand works. I will accept money from any source whatever if only my candidate will win and enact our own Perfect Society. Those who disagree with me are communists or fascists or red necks or whatever epithet will show my absolute disdain for anyone who dares to disagree.

When we can no longer compromise in government, we’re fated to know paralyzing dysfunction. When we require our society to be perfect, we risk losing it.