Anyone who suggests that we should compare welfare rates, crime rates, high school dropout rates and drunk driving arrest rates among immigrants from different countries before we set immigration quotas is likely to be stigmatized as a bad person.
Above all, we need to look at immigration laws in terms of how they affect the American people and the American culture that gives us a prosperity that has long been among the highest in the world.
Americans, after all, are not a separate race but people from many racial and ethnic backgrounds.
Yet most Americans have a higher standard of living than other people of the same racial or ethnic background in their respective ancestral home countries. That is even more true for black Americans than for white Americans.
Clearly, whatever we have in this country that makes life here better than in the countries from which most Americans originated is something worth preserving.
A hundred years ago, preserving the American way of life was much easier than today, because most of the people who came here then did so to become Americans, learn our language, and adopt our way of life.
Today, virtually every group has its own "leaders" promoting its separate identity and different way of life, backed up by zealots for multiculturalism and bilingualism in the general population.
The magic word "diversity" is repeated endlessly and insistently to banish concerns about the Balkanization of America - and banish examples provided by the tragic history of the Balkans.
We are importing many foreigners who stay foreign, if not hostile.
Blithely turning them into citizens by fiat, rather than because they have committed to the American way of life, is an irreversible decision that can easily turn out to be a dangerous gamble with the future of the whole society.
What happened in Boston shows just one of those dangers.
Sowell is a senior fellow at the Hoover Institution at Stanford University in California. His website is www.tsowell.com.