Compare and contrast
Two new blog entries on political science research on diversity.
Daniel Larison (at the new, revamped American Scene) on Robert Putnam's "Ethnic Diversity and Social Capital" research (see his Skytte Prize Lecture), showing that increases in local diversity can be "devastating" to social capital in all the affected communities; people hunker down in the face of unfamiliar neighbors, their intracommunal associational life dries up and intracommunal ones don't develop anytime soon.
Henry Farrell on Scott Page's book, The Difference, showing that under various not-too-restrictive conditions diversity in a pool of decisionmakers has benefits. Different perspectives, assuming that they're perspectives on a shared question, problem, or enterprise, can be more valuable than expertise. (Diverse agents with divergent preferences don't getthe same results.)
Note that these conclusions are entirely compatible with one another. A neighborhood isn't an enterprise association. It may be that the epistemic benefits of diversity can only be obtained in fairly artificially structured environments. (Most formal decisionmaking bodies are artificially structured environments.)
Add Putnam and Page to my reading pile; and puzzle over the implications for liberal theory and democratic theory respectively. Or else throw it out into the world and encourage a grad student to do the puzzling...