Sociologists have traditionally thought about the consequences of ethnic diversity in one of two ways. The ‘conflict’ model claims that the more that diverse groups interact, the more social tension there will be. The ‘contact’ model, on the other hand, suggests that the more that different groups interact, the less they will fear each other. Unsurprisingly the first model is favoured by conservatives to justify restrictions on immigration, while liberals often call on the second in arguing for multicultural education.

Then came Robert Putnam. Around the turn of the century, the American sociologist and his colleagues interviewed 30,000 people in 41 communities across America. Their data challenged both approaches. Putnam’s results discredited the idea that greater diversity is correlated either with increased inter-ethnic hostility or with greater understanding. Rather they suggested that it is associated with an erosion of trust across the board. Other things being equal, Putnam discovered, more diversity in a community meant less trust both between and within ethnic groups. The more diverse a community, the less socially engaged were its members – they voted less, did less community work, gave less to charity, and had fewer friends. Most strikingly, people in more diverse society people were more distrustful not just of members of other ethnic groups but of their own, too. According to Putnam, diversity ‘seems to trigger not in-group/out-group division, but anomie or social isolation’. To put it another way, ‘In more diverse settings, Americans distrust not merely people who do not look like them, but even people who do.’

Putnam’s research, and the suggestion that too much diversity undermines trust and mutual regard has been seized upon by critics of immigration such as David Goodhart and and Paul Collier. Putnam himself delayed publishing his full details for more than five years, fearful of its political implications.

More recent empirical research has, however, questioned the Putnam argument. The latest such study comes in the work of Patrick Sturgis, Professor of Research Methodology and Director of the ESRC National Centre for Research Methods. Sturgis and his colleagues investigated the relationship between diversity and trust in London, ’a city with a justifiable claim to be the most ethnically diverse, not just in the UK, but in the world’. It is, they write, ‘because we can be certain that ethnic diversity is unusually high and, therefore, part of everyday life for its residents that we have chosen to focus our analysis on neighbourhoods in London.’ ‘If living in an ethnically diverse neighbourhood causes people to distrust and avoid one another’, they reasoned, ‘then we should be certain to find evidence of the phenomenon in London.

The study discovered the opposite relationship to Putnam. Once Sturgis and his colleagues had allowed for social and economic deprivation, then ‘ethnic diversity is… positively related to social cohesion, with significantly higher levels of cohesion evident as ethnic heterogeneity increases’. The relationship between diversity and cohesion is age related. The positive effect of diversity is strongest among younger people and weakest among the oldest people, and is, indeed, marginally negative for those over 85.

‘Our overall conclusion’, the authors write, is that ‘ethnic diversity does not, in and of itself, drive down community cohesion and trust. In fact, in the highly diverse neighbourhoods that characterize modern London, the opposite appears to be the case, once adequate account is taken of the spatial distribution of immigrant groups within neighbourhoods and the degree of social and economic deprivation experienced by residents.’

We should no more view Sturgis’ research as demonstrating that diversity creates trust than we should have seen Putnam’s work as having demonstrated that diversity undermines trust. Both studies are restricted by geography, one being a study of American neighborhoods, the other of London neighboruhoods. Equally importantly they are studies restricted by history. As I have suggested before, a key problem in many studies of diversity is that each offers only a snapshot of attitudes at one moment in time. Diversity, though, is not a static phenomenon but the character and meaning, and our political response to it, changes over time. So, in thinking about the Putnam data, we need to remember that

Over the past few decades, we have witnessed the demise of movements for social change, the rise of identity politics, the atomization of society, a loss of belief in universal values, all of which has led to civic disengagement and a greater sense of anomie. The real problem, then, may not be diversity as such but the political context in which we think about it.

The real issue raised by such studies is the need to think far more carefully, and subtly, what we mean by diversity, trust and cohesion. These are all complex terms with multiple meanings but which in both academic and popular discourse all too often become stripped of that complexity and subtlety. Such studies reveal the need, too, to think not just sociologically but also historically, and not to imagine that either the way we conceive of particular concepts at a particular moment in time, or their impact on attitudes, relationships and social structures are given. Nor should we ignore the political context in which these debates take place. Notions of ‘diversity’, ‘trust’ and ‘cohesion’ do not come prepackaged but only emerge against particular political and historical backgrounds. That is why a historically static understanding of these issues is so stripped down and  impoverished.

Most importantly, perhaps, we should be wary of those commentators who take such studies, especially single studies, and use them as ‘evidence’ for grand political claims about immigration and diversity. These studies should become part of the debate. But of themselves they settle nothing.

The images are ‘Dance’ by Henri Matisse and Pablo Picasso’s ‘Mother and Child’