One of the memorable moments in my career was a lunch with Isaac Bashevis Singer. It took place in July 1984 at the home of Simon Weber, who was then editor of the Jewish Daily Forward. Weber lived on the top floor of an apartment block overlooking Brighton Beach in Brooklyn. I’ve often told the story. When lunch commenced, I reported that the Wall Street Journal, for which I was then working, had just come out in favor, at least in principle, of open borders. “Oy,” said the Nobel laureate, without looking up from the bagels and smoked fish, “all those Mexicans.”

His remark prompted me to slap the table and explain that I couldn’t believe a member of the Journal’s redaktzia, visiting the home of the editor of the newspaper that lit the way for the great wave of Jewish immigration into America, would hear the greatest immigrant writer of his generation exclaim, “Oy, all those Mexicans.” At which Si Weber summoned me onto his balcony, where, overlooking a section of New York in which English is hardly spoken, he wagged his finger at me and said, “I know you guys from the Wall Street Journal. All you want is cheap labor.”

Wouldn’t it have been nice to have been able to reach into my coat pocket for a copy of a book published 24 years later, “Let Them In: The Case for Open Borders,” which is the latest volume from a member of the Journal’s editorial board. Its author, Jason Riley, deals not only with the canard of cheap labor but has built his book around what he calls “six common arguments against immigration and why they are wrong.” Mr. Riley’s book will prove an invaluable and trusty volume for all who are engaged in the great debate over public policy in this country.

Mr. Riley starts with the population argument, or what he calls “doom and demography,” and the “odd political bedfellows” who have lined up against immigration. And not just illegal immigration. These are an amalgam of factions who, when allied, mix extreme environmentalism normally associated with the left with nativist, racist elements on the extreme right. Mr. Riley cites one survey of 20 U.S. environmental organizations that found 14 that “consider overpopulation to be ‘a problem.'” He notes that “‘stabilizing world population’ ranks fourth on the Sierra Club’s twenty-first-century to-do list.”

The answer to that argument is that economic growth is essential to a cleaner environment and population growth is essential to economic growth, which Mr. Riley deals with in a chapter called “Help Wanted.” He is an advocate of flexibility in the labor market, arguing that if America fails to maintain this flexibility — which is part of what attracts so many immigrants — its fate will be akin to the slowest growing of the major European economies, France.

In many ways, Mr. Riley’s is a radical book, embracing the economists who argue that in terms of promoting labor market flexibility and economic growth, illegal immigration may be more efficient than legal immigration. In his chapter on welfare, he has a wonderful section on static analysis, which, during the Reagan years, was the redoubt of those on the left who argued that supply-side tax cuts would reduce revenues — only to discover, as the Reagan boom unfolded, that the growth the tax cuts ignited economic growth that produced even greater revenues.

Mr. Riley faults at least some conservatives for abandoning dynamism and retreating to static analysis in the immigration debate. And he is at pains to carve out of the immigration argument the problem of black unemployment. “If you’re looking for a villain behind the black unemployment rate,” he writes, “try the welfare state.” Argues he: “The black family survived slavery, Reconstruction, and Jim Crow, but the well-intentioned Great Society sounded its death knell.” He gives the scoop to Daniel Patrick Moynihan. “Difficult as it may be to fathom today,” Mr. Riley writes, “black participation in the labor force in the 1950s more or less matched that of whites.”

In a chapter on assimilation, Mr. Riley deals with nativist arguments. He goes back to Benjamin Franklin, whom Mr. Riley quotes as having complained of German immigrants. The sage of Philadelphia called them “the most stupid of their nation” and asked, “Why should Pennsylvania, founded by the English, become a Colony of Aliens, who will shortly be so numerous as to Germanize us instead of us Anglifying them, and will never adopt our Language and Customs?” From there he takes on the faction among conservatives who oppose immigration on cultural grounds.

The big question is what all this means for 2008. Mr. Riley sketches how the fracturing of the Republicans intelligentsia and politicians over immigration foreshadowed the Republican rout in the mid-term elections of 2006. Since then the one politician who likes to voice a passionate pro-immigration position, Mayor Bloomberg, has stood down from the Republican Party, not to mention from the presidential race. Mr. Riley reckons, in a chapter called “Pup Tent Republicanism,” that the stumble by the GOP on the issue in 2006 may be the best thing the Democrats have going for them in 2008. It’s a disappointing denouement from the ironies that eddied through my lunch with the editor of the Jewish Daily Forward and I.B. Singer a generation ago.