From Ethan Zuckerman’s blog post.

The Guardian (UK) yesterday carried a wonderful column by Oliver Burkeman, “This column will change your life” on a topic dear to our heart—and mentioning LibraryThing to boot.

The topic is “homophily,” the “faintly depressing human tendency to seek out and spend time with those most similar to us.” Homophily informs whom we spent time with and filters our understanding of the wider world. As the author writes, his American friends were sure Obama was going to win:

“[T]hey hadn’t met one person—not one!—who planned on voting Republican. They were right about the outcome, of course. But 58m people voted against Obama; it was just that you didn’t run into them in the coffee shops of Brooklyn.”

Quoting the Harvard sociologist Ethan Zuckerman that “Homophily causes ignorance,” Burkeman adds that it tends to make people more extreme. The internet can increase the effect, allowing dittoheads of various persuasions to “exist almost entirely within a feedback loop shaped by your own preferences.”*

Burkeman closes by recommending the LibraryThing Unsuggester:

“You don’t need technology to do that, but then again, technology needn’t be the enemy: Facebook could easily offer a list of the People You’re Least Likely To Know; imagine what that could do for cross-cultural understanding. And I love the Unsuggester, a feature of the books site LibraryThing.com: enter a book you’ve recently read, and it’ll provide a list of titles least likely to appear alongside it on other people’s bookshelves. Tell it you’re a fan of Kant’s Critique Of Pure Reason, and it’ll suggest you read Confessions Of A Shopaholic by Sophie Kinsella. And maybe you should.”

The topic is interesting to me from a number of different angles. First, as a social network that works largely through shared reading, LibraryThing gets the upside of homophily and is subject to the downside too.

Second, with Zuckerman, I’ve fascinated by the notion of serendipity, of “surprising someone helpfully.” As I’ve argued to library audiences in the past, both Amazon-style collaborative filtering and contemporary library catalogs are bad at serendipity—worse, in some ways, than browsing physical shelves can be. As Zuckerman notes, the somewhat mechanical process of subject assignment can break through the “flocking together” tendency of collaborative filtering. But I bet there are better ways too. Is a true “serendipity algorithm” possible?

Third, my own experience is characterized by some rather vexed homophily issues. Zuckerman mentions “02138” at one point, no doubt baffling some internet listeners. It is, of course, the zipcode of Harvard and much of west Cambridge, where I grew up and spent most of my life. A popular t-shirt (I own one) proclaims “02138: The World’s Most Opinionated Zip Code,”** but there can be no mistaking that opinions largely go one way. Growing up in Cambridge, and attending a certain private school, taught me that respect for diversity was at the center of human virtues—something I still agree with—but that everyone had houses filled with books***, Volvo was the nation’s most popular automaker, that large families and stay-at-home mothers were suspect, that religion was for mental defectives, that Mondale was going to win in 1984, and so forth. In a very real way Cambridge taught me how to think—and I’ve spent the rest of my life thinking through what to keep and what to chuck.

For more on this topic, check out:

• Homophily, serendipity, xenophilia. Long, thoughtful blog post by Ethan Zuckerman.
• Technologies and Emerging Democracies: Building a Better Gatekeeper. Wonderful short talk by Zuckerman.

*David Weinberger has a very good reply somewhere—in Everything is Miscellaneous?—where David argues (as I recall) that this is an unrealistic notion. Conversations happen because of shared ground. I shall avoid thumbnailing any more because I shall surely get it wrong.
**See Flickr user Nabeel_H for the motto on a window, allegedly quoting the NYT. 02138 is now also the title of a Magazine for Harvard Alumni (see it). As a lifelong resident of 02138, but not a Harvard Alumnus, I am considerably irritated that four-years residence in that second-rate sausage factory gives people the right to claim my zipcode.
***Certain books, mind you. I am a great connoisseur of Cambridge bookshelves.