This may be off topic, but I have never been entirely able to accept that politics is the mind-killer. I suspect that two party politics may be killing the mind while multi-party systems are merely mind-numbing.
Where I live, we currently have 8 parties in parliament, let's call them the infra-reds, reds, oranges, yellows, greens, blues, indigos and violets. Currently, the blues and violets are in charge, but they need support from either the oranges or the greens and indigos in order to actually pass any laws or regulations. Last year, we had the reds, oranges and yellows in charge. (Nobody ever cares about the infra-reds because they are old-school revolutionary communists, but for some reason they usually manage to grab a seat or two.) My point is that with every decision being an obvious compromise and usually with most of the negotiations between the interesting parties out in the public media, politics is a significantly more nuanced exercise.
Politics in the sense of the title isn't limited to identifying with one faction within a party system; it has more to do with entangling your identity with us-vs.-them factionalism more generally. Now, in a two-party system, the battle lines are drawn a lot more clearly than in a multi-party, which provides the conditions for identifying strongly with a literal political party; a Democratic voter in the US probably thinks of their elections in more partisan terms than a Lib Dem voter in the UK, and both are probably more partisan than a UMP voter in Fran...
One of my favourite Less Wrong articles is Politics is the mindkiller. Part of the reason that political discussion so bad is the poor incentives - if you have little chance to change the outcome, then there is little reason to strive for truth or accuracy - but a large part of the reason is our pre-political attitudes and dispositions. I don't mean to suggest that there is a neat divide; clearly, there is a reflexive relation between the incentives within political discussion and our view of the appropriate purpose and scope of politics. Nevertheless, I think it's a useful distinction to make, and so I applaud the fact that Eliezer doesn't start his essays on the subject by talking about incentives, feedback or rational irrationality - instead he starts with the fact that our approach to politics is instinctively tribal.
This brings me to Joseph Bottum's excellent recent article in The American, The Post-Protestant Ethic and Spirit of America. This charts what he sees as the tribal changes within America that have shaped current attitudes to politics. I think it's best seen in conjunction with Arnold Kling's excellent The Three Languages of Politics; while Kling talks about the political language and rhetoric of modern American political groupings, Bottum's essay is more about the social changes that have led to these kinds of language and rhetoric.
Video of a related lecture can also be found here.