In the theoretical toolkit of social science we find two diametrically opposed perspectives on the effects of diversity on social connections. The first, usually labelled the “contact hypothesis”, argues that diversity fosters interethnic tolerance and social solidarity. As we have more contact with people who are unlike us, we overcome our initial hesitation and ignorance and come to trust them more. More formally, according to this theory, diversity reduces ethnocentric attitudes and fosters out-group trust and solidarity. For progressives, the contact theory is alluring, but I think it is fair to say that most (though not all) empirical studies have tended instead to support the so-called “conflict theory”, which suggests that, for various reasons (above all, contention over limited resources) diversity fosters out-group distrust and in-group solidarity. On this theory, the more we are brought into physical proximity with people of another race or ethnic background, the more we stick to ‘our own’ and the less we trust the ‘other’.
Contact theory suggests that diversity erodes the in-group/out-group distinction and enhances out-group solidarity or bridging social capital, thus lowering ethnocentrism. Conflict theory suggests that diversity enhances the in-group/out-group distinction and strengthens in-group solidarity or bonding social capital, thus increasing ethnocentrism. However, once we recognize that in-group and outgroup attitudes need not be reciprocally related, but can vary independently, then we need to allow, logically at least, for the possibility that diversity might actually reduce both in-group and out-group solidarity – that is, both bonding and bridging social capital. We might label this possibility ‘constrict theory’. Diversity seems to trigger not in-group/out-group division, but anomie or social isolation. In colloquial language, people living in ethnically diverse settings appear to ‘hunker down’ – that is, to pull in like a turtle.
A wide array of other measures of social capital and civic engagement are also negatively correlated with ethnic diversity. Diversity does not produce ‘bad race relations’ or ethnically-defined group hostility, our findings suggest. Rather, inhabitants of diverse communities tend to withdraw from collective life, to distrust their neighbours, regardless of the colour of their skin, to withdraw even from close friends, to expect the worst from their community and its leaders, to volunteer less, give less to charity and work on community projects less often, to register to vote less, to agitate for social reform more, but have less faith that they can actually make a difference, and to huddle unhappily in front of the television. Note that this pattern encompasses attitudes and behavior, bridging and bonding social capital, public and private connections. Diversity, at least in the short run, seems to bring out the turtle in all of us.
[E Pluribus Unum: Diversity and Community in the Twenty-first Century. The 2006 Johan Skytte Prize Lecture. 2007 Nordic Political Science Association. Robert D. Putnam]