Trust is important because it acts as a kind of social glue that enables business and communities to operate more effectively. In regions where people trust one another, institutions, markets and societies seem to work better. Trusting societies have more effective bureaucracies, schools that function more efficiently, less corruption and faster growth.
Trust, though, is undermined by ethno-linguistic diversity. This, at least, is what Dr Leigh found when he researched data from the Australian Community Survey. Dr Leigh found that:
Neighbourhood-level analysis also throws up a startling finding: trust is lower in ethnically diverse neighbourhoods ... The effect of diversity operates on immigrants and locals alike. In more linguistically diverse suburbs, both foreign-born and Australian-born residents are less inclined to trust those around them.
Dr Leigh believes that this pattern, in which diversity is associated with low levels of trust, holds true elsewhere:
The negative relationship between trust and ethnic diversity is not unique to Australia. Separate studies looking at the US, Britain, India, Kenya and Pakistan have shown that diversity is associated with lower levels of trust and less investment in shared resources. In the US, work by Alberto Alesina and Eliana La Ferrara has produced very similar results to my own: holding constant a raft of other factors, US cities that are more diverse tend to be less trusting. Other research has reached similar conclusions.
Dr Leigh's research corresponds closely to the well-publicised findings of Professor Robert Putnam of Harvard University. Professor Putnam's research shows that:
the more diverse a community is, the less likely its neighbours are to trust anyone ... "in the presence of diversity, we hunker down ... We act like turtles. The effect of diversity is worse than had been imagined."
So what does Dr Leigh conclude from all this? He makes it very clear throughout his article that he supports continuing large-scale immigration, despite the negative effect that diversity has on trust.
Significantly, he concludes his article with this quote from Professor Putnam:
Growing up in a small Ohio town in the 1950s, I knew the religion of just about every kid in my 600 person high school ... when my children attended high school in the 1980s, they didn't know the religion of practically anyone, it simply didn't matter ..."
In my lifetime, Americans have deconstructed religion as a basis for making decisions. Why can't we do the same thing with other types of diversity?
So here we get back to a basic problem liberal modernists like Professor Putnam and Dr Leigh face, namely of having to make things which matter, not matter. The "hope" of these men is that ethnicity might be somehow deconstructed and made unimportant to people, so that high levels of immigration, and therefore high levels of ethnic diversity, might be able to coexist with high levels of neighbourhood trust.
Ethnicity, though, is what places people within a larger tradition, and connects them closely to a particular culture and community. It's not really the kind of thing which is secondary and which can reasonably be sacrificed to the goals, or the decision making processes, favoured by economists.
What happens when diversity does become the reality? As might be expected, it can be experienced negatively, as something alienating. As an example of this, consider the recently reported reaction of Oliver James, a prominent British author and psychologist, to modern Sydney. He thought the city itself was "beautiful and spacious" but he nonetheless became "unsettled" as he was driven into town:
Oxford Street was like the "Tower of Babel, a confusing polyglot in its diversity". There were people from "all the ends of the Earth", creating a feeling of "identitylessness, so you feel like you could be from anywhere.
English journalist, Peter Whittle, wrote along similar lines about the transformation by immigration of the London suburb he had grown up in:
Sometimes now, in streets I've used since Sixties boyhood, I'm struck by the sense that I should no longer think of this place as providing my identifiable roots, and that I am simply one of many who happen to be living here, with no greater claim to it sentimentally or historically. Such anonymity might be what people are looking for when they choose to live in the teeming metropolitan centre, but in a suburb which has shaped much of your life it's a much harder feeling to negotiate.
This part of south-east London has never been affluent ... But it had something which amounted to a collective identity. Now, it appears to me fragmented, with different ethnic communities existing side-by-side, sometimes uneasily, and always with a sense of nothingness in the air.
What kind of social policy can adequately replace this kind of loss? I don't believe there is one which can even begin to compensate. A better aim would be to support the continued existence of traditional community life, rather than insisting on ever increasing levels of diversity.