Let’s just say it plainly: The United States needs more low-skilled immigrants.

You might consider, for starters, the enormous demand for low-skilled workers, which could well go unmet as the baby boom generation ages out of the labor force, eroding the labor supply. Eight of the 15 occupations expected to experience the fastest growth between 2014 and 2024 — personal care and home health aides, food preparation workers, janitors and the like — require no schooling at all.

“Ten years from now, there are going to be lots of older people with relatively few low-skilled workers to change their bedpans,” said David Card, a professor of economics at the University of California, Berkeley. “That is going to be a huge problem.”

But the argument for low-skilled immigration is not just about filling an employment hole. The millions of immigrants of little skill who swept into the work force in the 25 years up to the onset of the Great Recession — the men washing dishes in the back of the restaurant, the women emptying the trash bins in office buildings — have largely improved the lives of Americans.

The politics of immigration are driven, to this day, by the proposition that immigrant laborers take the jobs and depress the wages of Americans competing with them in the work force. It is a mechanical statement of the law of supply and demand: More workers spilling in over the border will inevitably reduce the price of work.