WASHINGTON — Half a million people poured into the streets of Los Angeles on Saturday, chanting slogans in Spanish and waving the Mexican flag, to protest the various Republican-sponsored proposals in Congress that would demonize illegal immigrants. Hundreds marched Monday in Detroit, which, last I checked, is nowhere near the Mexican border. Tens of thousands have demonstrated in Phoenix, Denver and other cities across the country. In every case, the crowds were mostly Latino.

We all know that Latinos are the nation's largest minority, and that most of the people in those demonstrations either were born in the United States or are here legally. But we also know that at least some of those protesters had gone through the experience of crossing the border illegally under the tutelage of avaricious people-smugglers known as "coyotes." At least some had been here for months or years, working to send money home to their families, keeping their heads down, somehow managing to carve out lives for themselves and their children.

Who are they? After the demonstrations were over, where did they go? Are they so diabolically clever at hiding in plain sight? Or is it that the rest of us refuse to see them, because by seeing them we would have to acknowledge their humanity?

That willful blindness is why the debate on illegal immigration is so hypocritical. If we lump undocumented immigrants into an undifferentiated mass of Those People, we can avoid really looking at the immigrant experience. And we can convince ourselves that it is somehow different from the periodic waves of immigration that have shaped this nation — that suddenly it is not an issue or even a problem, but an urgent crisis.

There are an estimated 12 million immigrants in the United States illegally. That many people don't just fade into the woodwork. The fact is, we see undocumented immigrants every day.

Maybe they vacuum your office at night. Maybe they landscape your garden or clean your house or cook the food at your favorite restaurant. You probably don't know where they live. You probably don't know their children's names or where they go to school. You probably don't know what it was like for them to buy a car or even get a driver's license. You probably don't know where they get medical care.

If you did know these things about individual immigrants, whether they're from Mexico or El Salvador or China or Brazil, I think you would find the debate in Congress almost grotesque.