Andrew Sullivan has a post today about the resurgence of ideological purism, quoting a reader who describes being ostracized from a left-wing group for believing that the U.S. did not deserve the 9/11 attacks.

I agree that such purism is nefarious and prevalent, but I'm not sure it's on the rise. Weblogistan certainly gives it a new and powerful platform, and so many of the top sites seem to be specifically catered to readers who know what opinions they want to read and know where they can consistently find them. In my experience, however, ideological purism has been both a constant threat and a consistent temptation, and it is by no means limited to politics.

When I was in my late teens and early 20s, I was a full-on music snob. I would express shock when a like-minded connoisseur would express an appreciation for, say, Pearl Jam, and I would feel pangs of shame if I caught myself singing along to Madonna or some other cantor non grata in the hipster universe (nowadays it is perfectly OK for a hipster to like Madonna; extra points if it's an ironic appreciation). Worst of all, I would pass judgment on others for their music taste, attributing their penchant for Squeeze or the J. Geils Band to ignorance or some sort of brain defect.

I have since learned a powerful lesson: I was being an asshole.

Around the height of my music snobbery, I was also an insufferable, puritanical scold when it came to politics and a host of other things as well. I think this is normal for college-aged people who are just coming into adult political and cultural consciousness. Orthodoxy and identification with a group or "type" provide a powerful mooring for the tenderfoot. The problem comes when people can't leave the vestiges of adolescence behind.

In real life, identifying yourself wholeheartedly with a "kind of people" is the most insidious form of groupthink and it strips away at the core of your individuality. Any political movement that demands absolute homogeneity from its adherents is suspect, if not downright dangerous. The core responsibility of adherents to Nazism or communism—or any cult-like group for that matter—is fealty to the infallible leadership and the ideals which they jealously guard. Individuality and free-thinking are anathema in an organization where any one member can be expected, as Georg Lukács wrote, to sacrifice his inferior self on the altar of the higher idea.