Finding all things Putnam-related, Steve Sailer points us to this 2004 Economist story, which reported:

Less back-slapping will occur during Mr Putnam’s return visit next week, to a private seminar organised by the home secretary. That is because his research has taken a dismal turn. A large ongoing survey of American communities seems to show, uncomfortably, that levels of trust and co-operation are highest in the most homogenous neighbourhoods. People living in diverse areas, it turns out, are not just more suspicious of people who don’t look like them; they are also more suspicious of their own kind. Because of that, they suffer socially, economically and politically. 

It may be worth noting that this lack of trust also functions as an obstacle to the creation of social democratic welfare systems, as a lack of social homogeneity seems to make people less willing to support such a system when it is for the benefit of a different group of people.  Scandinavian welfarism has succeeded, if we can call it success, because of their (until recently) almost entirely homogenous populations.  Thus it is often in those countries with the most elaborate dole systems that mass immigration causes the greatest resentment.  Earlier in the same week in February 2004, The Guardian published David Goodhart’s essay, in which he advanced this argument that promoting and celebrating ethnic diversity actually weakened support for social welfarism.  Thus Goodhart:

Evolutionary psychology stresses both the universality of most human traits and - through the notion of kin selection and reciprocal altruism - the instinct to favour our own. Social psychologists also argue that the tendency to perceive in-groups and out-groups, however ephemeral, is innate. In any case, Burkeans claim to have common sense on their side. They argue that we feel more comfortable with, and are readier to share with and sacrifice for, those with whom we have shared histories and similar values. To put it bluntly - most of us prefer our own kind.  

But what if you are like Bagehot, who finds “his own kind” to be tyrannical and an impediment to an exciting, creative life?  To explain, here’s The Economist again:

Even if there were a stark choice between diversity and social solidarity, it is not clear that the latter would be better. In 1856 Walter Bagehot, deprived of the diversity which the past century and a half has brought, railed against his tight-knit society, which he thought stifled excitement and innovative thinking. “You may talk of the tyranny of Nero and Tiberius,” he wrote, “but the real tyranny is the tyranny of your next-door neighbour.”

Certainly one can sympathise with Mr. Bagehot’s neighbours, who probably felt just as strongly about the frequent impositions of his views that he made upon the community, but what we have here is nothing so much as the perfect example of someone not knowing how good he has it.  There was a fair amount of innovative thinking going on in mid-19th century Britain, as Steve Sailer notes, so what can it possibly mean to say that a tight-knit society of Bagehot’s day ”stifles excitement and innovative thinking”?  Presumably, the “excitement” Bagehot sought is not that of what people euphemistically call “vibrant” neighbourhoods (on why writers should avoid using the word vibrant, see here).  As for “innovative thinking,” why would it be the case that increased diversity would produce it?  If diversity helps to weaken bonds of trust between and within groups, it probably also encourages people to retreat into ever-more comfortable and lazy assumptions as effective communication and the exchange of information go the way of trust.  It adds nothing to ”innovative thinking” if the different groups in a city or country do not speak much to each other because of fear and suspicion, and it adds nothing if they do not even use the same language.    

Usually whenever a multiculti makes comparisons between the “tight-knit” homogenous society and what would have to be the “threadbare” diverse society, he summons a vision of an impoverished village of illiterate pig farmers on the one hand and the pulsating energy of pre-1997 Hong Kong, and then asks his urbanite audience, “Where would you rather live?  In a penthouse in Hong Kong or in a thatched hut with no floor among the pigs?  See, diversity is great!”  Somehow I suspect the average person’s experience of the boons of diversity is more like the mutual suspicion and hostility of modern L.A.  For what’s worth, I would wager that people living in Baghdad today would prefer less “excitement” and more real neighbourliness.  Baghdadis do have to worry about the “tyranny of the neighbour,” but this is mainly because their neighbours are of a different sect in a time when sectarian identity has become far more pronounced and meaningful.  Obviously, when there is no social cohesion, people have a hard enough time surviving, much less engaging in “innovative thinking.”