Diversity has a downside.

Preposterous? In the world of academia, where administrators eat, sleep and breathe the concept of multiculturalism, such a statement surely is. Yet it was one of the academy's own, Harvard political scientist Robert Putnam — a self-described liberal, no less — who reached the seemingly blasphemous conclusion in a study released earlier this year in the journal Scandinavian Political Studies.

Culling data from nearly 30,000 interviews in 41 sites across the U.S., Mr. Putnam found diversity exerts a negative effect on a host of civic and social indicators in communities. In racially diverse neighborhoods, people volunteer less. They vote less often. They have fewer friends. They give less to charity. They stay at home more often. They harbor more negative thoughts about their local governments. On the whole, people trust each other less — and not only members of other races, but even those of the same race as themselves.

According to Mr. Putman, the trend applies to communities both large and small. It applies regardless of a whether a community is rich or poor, or whether it has a high or low crime rate.

Most people likely shrug when they learn of Mr. Putnam's findings. If world history can be boiled down to one blanket statement, it could be this: People don't always get along with people who are different from themselves. Given a choice, people generally like to be around people with whom they are similar. Mr. Putnam's empirical findings hardly speak to any revelation.

Yet his research reminds us that there are challenges to be faced by any country with a diversifying population. Cultural issues can't just be summarily dismissed as irrelevant.

But before you award the 21st century to a homogenous country — say, oh, China — be aware that people do eventually come to trust each other and form new bonds. In the long run, diversity leads to a vitality that is positive, according to Mr. Putnam. The United States will be quite all right.

The question, then, is how to handle increasing diversity before its benefits become visibly apparent. It's not an easy question to answer.

There seems to be one approach, however, that must be rejected. It's called multiculturalism, and it's championed by almost every university administrator in the land, along with assorted others on the left.

Under the multiculturalist approach, people are encouraged to identify first and foremost as members of their particular race. Assimilation is treated as a dirty word. Discussions of race and ethnicity are encouraged, but only if the dialogue fits a certain worldview and level of political correctness. Members of certain races are assumed to be oppressed, which logically requires that others be oppressors — a tacit assumption usually, though occasionally explicitly, as evidenced by a recent housing program policy at the University of Delaware that amounted to nothing short of indoctrination.

To drive a further wedge between people, multiculturalists insist on treating different races disparately. When decisions could be left exclusively to the merits, such as school admissions, they inject race as a factor.

Given Mr. Putnam's research findings, the multiculturalist approach would seem, on the surface, to be an appropriate plan of action. Since different cultures are a little wary of each other, why not bring everybody together and talk things through?

The problem with the approach is that diversity, simply for the sake of diversity, isn't much good. Happy, productive, diverse communities can't be manufactured — they must come organically. Residential patterns in this country — currently largely de facto segregated — will change over time, but it won't be an instant process.

Earlier this year, the United States Supreme Court struck down enrollment plans in Seattle and Louisville that assigned students to particular city schools because of their race, such that each school would maintain a certain racial mix. Writing for the majority, Chief Justice John Roberts remarked simply, "The way to stop discrimination on the basis of race is to stop discriminating on the basis of race."

Mr. Robert's statement drives home a certain point: Instead of accentuating differences — as is the essence of multiculturalism — commonality must be sought. Then, and only then, can the inconvenient findings of Mr. Putnam's research be overcome.

Ryan Masse ([email protected]) is a first-year law student.