I've changed the tagline to this blog. "An extremist, not a fanatic" is intended to highlight a much overlooked distinction. It endorse A.J.P Taylor's quip - "extreme views, weakly held" - against the "passion" of our political leaders.
What puzzles me about so many people is not what they believe, but the sheer vehemence with which they do so.
I suspect there are at least four biases that cause such fanaticism.
1. Over-rating intellect and learning. Most politically active people are more intelligent or better educated than average. And a common error amongst intelligent educated people is to exaggerate the importance of intelligence and learning. They forget (or never knew) Hayek's insight, that knowledge is inherently dispersed, and unattainable by any single mind.
2. Ego involvement. Political views define who we are, so a challenge to them is a challenge to our identity.
3. Groupthink. For most of us, there's a huge correlation between our political opinions and those of our friends. Hardly anyone echoes Robert Nozicks' view: "I do not welcome the fact that most people I know and respect disagree with me" (quoted in this great book). This means we become over-confident in our opinions, bolstered by the fact that so many good people agree with us.
4. Incentives. One problem with vulgar democracy is that incentives favour cheap talk. If we overstate our case, government is more likely to listen to us than if we state our case to the extent warranted by the evidence. Hence the importance of "community leaders."
These biases - there may be others - mean that people with centrist views can be irrational too. They also mean we shouldn't expect political debate to be fruitful or even enlightening.
Still, we can try, can't we?