There is plentiful historical evidence that cultural diversity and immigration need not undermine a society's cohesion. They can be sources of enrichment and renewal. Especially in a vital civilization, groups of different religious, ethnic, and national origin may be pulled, however reluctantly in particular cases, into a dynamic arid fertile consensus.
One problem with immigration into the United States today is that, at current levels, it complicates assimilation. The number of foreign-born residents is higher than at any time in American history. Over 40 percent of the residents of New York City speak a foreign language at home. In Miami the figure is 75 percent. At the same time, many immigrants resist integration into a common national culture; some groups pursue separate ethnic or racial identities.
The impact of mass immigration and separatism cannot be assessed without considering the ever-present need to balance unity and diversity. It is important to ask whether American culture still has sufficient centripetal and harmonizing pull to avert social fragmentation. Whatever other problems may attend multiculturalism and immigration, they are straining an increasingly fragile social fabric. The question arises whether there are sources of order in American society, actual or potential, that can moderate and balance the centrifugal influences. Or does the strain on society need to be reduced?