Let me tell you about one of the most frightening moments of my life. It came when I was at university, spending a week in Blackpool as a delegate to the National Union of Students conference.
Clearly, if that's one of the most frightening things he has witnessed he needs to get out more. He goes on to compare an NUS meeting seeking to expel a group of Tories to a Nuremberg rally. Yes really.
I have two serious-ish points to make. First, it's worth noting in passing that Sunstein describes Mandela as an extremist in the book - but one with a valid cause. He also talks about 'good extremism'. And obviously the Finkster's terrifying experience with the NUS was directly related to the anti-apartheid cause. I'm not saying that this excuses the behaviour he describes, or that Sunstein provides justification for it either. Just it's a bit odd that he doesn't make this link.
Secondly, though I regard myself as a moderate lefty, I found this bit of his post really annoying:
I believe that the work, and now the life, of Cass Sunstein provide a lesson to political moderates. The views of individuals change when they are part of groups. Certainty becomes greater as theories are corroborated, people gather information that confirms their earlier views, and group members seek approval from others. All this pushes individuals farther in the direction they were already inclined to go. Professor Sunstein calls his book Going to Extremes, but group polarisation means that a mildly centrist group would become more resolutely centrist.
What I don't like about it is the implication that being a centrist is the same as being a moderate. There are two problems with this in my opinion. First, being a centrist (as in somewhere between Left and Right) does not at all mean that you are a moderate. If both Left and Right agree on immigration controls, and you plant your flag between them, that doesn't make you a moderate on the issue in general, it just means you have split the difference between two dominant views. Also what about historical drift? What was the 'moderate' position on a sensible level of public ownership of industry 30 years ago, and what is it now? The moderate if they are a centrist will have just floated on the surface as the tide of this debate shifted.
Secondly, and more importantly, this idea of left/right/centre is generally pretty hopeless because it encourages people to think that these concepts sit on a map with almost measurable distances between them. It is a really unhelpful metaphor. The clustering of sometimes inconsistent political beliefs around the poles of Left and Right should tell us that it is not that simple. Centrists can be extremists too, and not in the sense of extremely moderate.