One of the great benefits touted by diversiphiles -- those who love diversity and promote it everywhere they can -- is that having a diverse student body, for example, would teach each group to respect and understand the others. But in a new study Robert Putnam finds that "in the presence of diversity, we hunker down".

We act like turtles. The effect of diversity is worse than had been imagined. And it's not just that we don't trust people who are not like us. In diverse communities, we don't trust people who do look like us.

Is there such a thing as "cultural convergence"? Interestingly, four years ago Putnam was saying something different. I am not sure why we find this surprising; even in his relatively famous "Bowling Alone", Putnam found that a high degree of homogeneity is needed to form "social capital" -- a term I have never used with great comfort.

This really isn't that unusual a conclusion. Economists for some time (one example) have understood that group formation is lower when groups are more heterogeneous. I noted this because of a paper I read a few years ago for a conference in which the writer found that racially heterogeneous counties answered the mailed form of the Census at lower rates than those more homogeneous. That is to say, the efforts of diversiphiles in admissions offices has to extend well beyond simply bringing the students together and singing "Why Can't We Be Friends?"