The number of immigrants who might someday turn into terrorists is small. Yet it only takes a few to cause trouble. And terrorism is only an extreme symptom of a far larger problem. A massive new wave of only superficially assimilated citizens would undercut the shared civic beliefs that have long held America together. On top of that, the new wave of Republican support for immigration reform assumes a pattern of assimilation that is no longer typical of this country.

So the Boston bombings are a wake-up call that ought to place the broader issue of assimilation at the center of our immigration debate. America’s experiment with multiculturalism has made us more like Europe when it comes to patterns of assimilation (or lack thereof) and less like the America of old. Although the implications of this change include the danger of terrorism, they extend to the strength of our shared ideas of citizenship. Fonte and Nagai show that our ideals citizenship, civic participation, and constitutional government have all been weakened by the breakdown in patriotic assimilation.

Turning to the latest spate of articles on the Boston-immigration connection, it’s clear that including the missing assimilation issue would thoroughly transform the debate. One common argument, for example, is that Boston is irrelevant because the Tsarnaevs were legal immigrants. But if patriotic assimilation is failing even for legal immigrants with years of experience in America, then a path to citizenship would only aggravate the problem (in the absence of the deeper reforms proposed by Fonte and Nagai).