[Note: I’m still trying to acclimatize to the pace of working on a Presidential campaign (I love saying that), so for the next few days I’ll be recycling material.]
In his latest report, Technorati founder and CEO David Sifry claims that in the last 20 months, the blogosphere has increased in size by over 16 times. Technorati now tracks over 7.8 million blogs which, if Montaigne is correct, makes for a great deal of diversity. Yet if opinions are so dissimilar, why does their appear to be a general homogeneity of viewpoints within the world of blogging? Why can the vast majority of blogs be grouped according to binary political categories? A forty year old experiment on racial diversity might just hold the answer.
In the 1960's, the Harvard economics professor Thomas C. Schelling devised a simple model to test his intuitions about segregated neighborhoods. Shelling found that most neighborhoods in America were mostly or entirely comprised of black or white families. Only a handful of neighborhoods where found where neither race made up more than three fourths of the total. Racism seemed to be the obvious culprit for the lack of diversity but Schelling thought something else might be involved.
His model showed how even tolerant people can behave in ways that can lead to segregated neighborhoods. It consisted of a checkerboard with 64 squares representing places where people can live. Two types of actors (representing, for example, whites and blacks) are placed at random among the squares, with no more than one per square. Schelling provided a "rule" that an actor will be content if more than one-third of its immediate neighbors (those in adjacent squares) are of the same type as itself. For example, if all the eight adjacent squares were occupied, then the actor is content if at least three of them are the same type itself as itself. If an actor is content, it stays put. If it is not content it moves. In Schelling's original model, it would move to one of the nearest squares where it would be content.
Not surprisingly, Schelling found that the board quickly evolved into a strongly segregated pattern if the agents' "happiness rules" were specified so that segregation was heavily favored. What was unexpected, though, was that initially integrated boards tipped into full segregation even if the agents' happiness rules expressed only a mild preference for having neighbors of their own type.
Figure 1 on the right shows four stages in a simulation run by The Atlantic's
Schelling's model implied that even the simplest of societies could produce outcomes that were simultaneously orderly and unintended: outcomes that were in no sense accidental, but also in no sense deliberate. "The interplay of individual choices, where unorganized segregation is concerned, is a complex system with collective results that bear no close relation to the individual intent," he wrote in 1969. In other words, even in this extremely crude little world, knowing individuals' intent does not allow you to foresee the social outcome, and knowing the social outcome does not give you an accurate picture of individuals' intent.
While the applicability to real-world housing situation may be a bit suspect, I believe that the model could provide some valuable insight into how blog clusters develop. Bloggers, for instance, would only need a mild preference for reading blogs that hold similar opinion to their own for clusters to develop spontaneously. If Schelling's model is correct, the broad diversity of viewpoints among individuals would inevitably lead them to link and interact more often with those who hold similar opinions. Over time, the eight million blogs would naturally fall into distinct groupings that would cause them to appear rather homogeneous. "Micromotives," as Schelling calls them, would lead to strikingly peculiar "macrobehavior."
Montaigne was correct when he claimed that opinions are as different as grains of sand. But just as sand collectively combines into dunes and beaches, opinions in the blogosphere collect into distinct clusters, swarms, and alliances. Oddly enough, it may just be the extreme diversity that creates congruity.
Note: A downloadable version of the Schelling Segregation Model can be found on this page.

This makes a great deal of intuitive sense. I help administer an online interfaith religious forum. Even though it is among the largest interfaith forums on the net, it is nowhere near in size to several single-faith forums. I would guess most people prefer their own kind to mingling with a diverse group.
I think there's a simpler explanation for the homogeneity that is to be found in conservative blogs:
"That’s what I mean by influential. I mean, talk about a direct IV into the vein of your support. It’s a very efficient way to communicate. They regurgitate exactly and put up on their blogs what you said to them. It is something that we’ve cultivated and have really tried to put quite a bit of focus on."
Fascinating post, Joe. Even if it is recycled.
I attended a Christian college where blacks and whites tended to live in different dorms, hang out in different places, Periodically there would be accusations of racism because of how segregated the school was, but in my experience neither the whites nor the blacks were really racist (with the possible exception of a few bad apples. Segregation just seemed to *happen*.
Schelling's model explains very well how segregation can spring up in a society that isn't vehemently racist but still has a slight preference to be near other people who are like them. Bravo!
People want to associate with those most like them.
In fact, I recall reading a news article recently which reported that people who hear political opinions that were aligned with their own exhibited a more positive physiologically response than to opinions that were politically no aligned. In other words, similar opinions made them feel better.
I can't imagine how this wouldn't similarly extend beyond the world of political though to personal associations.
Birds of a feather flock together. It's as simple as that. Which is why diversity only works when it is imposed from above. By force.