And that's where it stood until recently. One major study that unambiguously shows ethnic diversity is bad for society.
And then in late 2013, a pair of social psychology researchers at Michigan State University (Zachary & Jennifer Neal) published The (In)compatibility of Diversity and Sense of Community. Here's the abstract:
Despite the repetition and academic word-salad, this artful piece of 888 disguises the seriously non-PC nature of what these researchers found when they modeled social relationship formation using like-preference and proximity weighting.
They spend the first couple of pages of the study reassuring everyone that they are doubleplus goodthinkers, emphasizing that the promotion of respect for diversity is a high priority for community psychologists (WTF?). They ever-so-gently work their way around to the uncomfortable fact that diversity and community cohesion seem to be almost tautologically exclusive every time they're investigated together. They note that a few other researchers have been noticing this too, and studying it. That's where the paper gets interesting.
They begin by referring to an apparent "Community-Diversity Dialectic." This is academic-speak for "diversity and community seem to be in opposition to each other all the time." They reference a paper by Townley, Kloos, Green, et al. titled Reconcilable Differences? Human diversity, cultural relativity, and sense of community (which I haven't read, but now plan to), in which there is posited an inverse relationship between community and diversity, backed up by several empirical studies. Neal & Neal also note:
Of course, we can file this under "No s**t
They reference a bunch of other studies too, covering a wide range of demographics and contexts, coming to the conclusion that diversity and community "may not be compatible." (WOW JUST WOW)
They also follow this up with a quick bit of LOL that has to be quoted in full so you can appreciate how retarded progressives have become:
COMMUNITY AND DIVERSITY AREN'T IN CONFLICT AT ALL IF WE DEFINE COMMUNITY TO MEAN DIVERSITY!
None of the authors of the Townley paper are obvious members of the tribe nor known to be under clinical care, but this redefinition of terms approach to make community a purely transactional bridge absolutely reeks of talmudic logic and the 'tism . Fortunately, Neal & Neal aren't buying that specious line of argument one bit.
So what do they do? They build an agent-based model of human social behavior and relationship formation, in which they set up abstractions of simulated neighborhood containing to types of people. The "type" categorization is sufficiently generic that it is not solely representative of ethnicity, but of many other types of difference as well. As they put it, the difference of type is due to difference in "any socially consequential characteristic." The important thing is that the agents make decisions based on perceived difference, hence the 'socially consequential' parameter.
The "neighborhoods" are defined by their relative level of residential integration among the two types in each case, according to the percentage of one's neighbors out to certain radii who are dissimilar to each agent, ranging from 0.0 (homogenous) to 0.50 (fully integrated). They do not consider values greater than 0.50 (dissortatively mixed) because preliminary simulations find that the rare cases where that value might occur do not effect the results.
There is also a relationship-formation model in which homophily and proximity are the primary interaction criteria. Homophily is the documented tendency for people to form social relationships more quickly with people who are more like themselves. Proximity is the documented tendency for people to form social relationships more quickly with people who are in closer proximity to themselves. There's a bunch of technical description of how they set this model up, and then they run it, iteratively, a whole bunch of times for different cases.
So, what were the results?
The discussion section follows with a whole lot of 888 about what this might not necessarily be the soul-crushing bad news for progressives that it appears to be, but it's generally unconvincing. They also ultimately admit right out that community isn't a primary goal, it's subservient to diversity: "...we speculate that favoring a respect for diversity over a sense of community may often be preferable." That sentence could be ImmigrationPolicy.txt.
They close by noting that, since their results show that diversity and community are mutually incompatible, and given the universality of the behavioral tendencies that drive their model and its results, the simultaneous promotion of both in the real world is likely to be impossible.