Today, Krikorian and Jiménez debate the effects and future of tougher immigration enforcement. Later in the week, they'll discuss immigration as an issue in the presidential primaries, Real ID and more.

All we are saying is give enforcement a chance

Illegal aliens are people too.

And precisely because they are people like any others, they respond to incentives just like anyone else. What we've seen over the past year or so is that when government changes the incentives that illegal immigrants face, they change their behavior.

In other words, immigration enforcement is working.

By the end of this year, about half the additional border fencing mandated by Congress should be complete. Deportations and detention beds are up significantly. The Department of Homeland Security is pushing ahead with efforts to expose illegal workers who provided fake or stolen Social Security numbers to their employers. Sometime this year, all federal contractors will be required to check the legal status of new hires using the online E-Verify program. And virtually every state legislature in the nation is considering tough new immigration control measures, following in the footsteps of Georgia, Oklahoma, Arizona and Colorado.

The results are starting to come in. Fewer people are sneaking across the Mexican border. Some illegal immigrants are deporting themselves, while others are moving to less-inhospitable states, ensuring crackdowns there as well. Workplace enforcement is forcing employers to reach out to unemployed and underemployed American workers, as well as to turn to labor-saving technologies.

Are immigration restrictionists happy? You bet. But regaining control of immigration is a process, not an event. Our approach cannot be to focus intensively on enforcement for a few months or a year and then declare the borders secure and return to business as usual. This is has happened in the past — for instance, after the 1986 immigration law making it illegal for the first time to employ an illegal alien, crossings from Mexico fell until it became clear we didn't mean it, at which point they started rising again. This would appear to be what Sen. John McCain has in mind when he has spoken of a one- or two-year period of enforcement before implementing his amnesty.

Instead, the goal must be to change the climate surrounding the issue, to "define deviancy up," to adapt former Sen. Daniel Patrick Moynihan's phrase. Specifically, this would mean things like making legal status a labor standard that is internalized by employers and ensuring that visitors from abroad have good reason to fear that if they overstay their visas, they'll be identified.

Reducing the illegal population by cutting the inflow and increasing the outflow is not a pipe dream; we've seen self-deportation work on small scales before. For instance, after 9/11, Pakistani illegal aliens, the largest group from the Islamic world, got the message that circumstances for them had changed, and for every one detained by immigration authorities, 10 self-deported.

My own institution has modeled that consistent enforcement with a modest increase in resources over existing plans could reduce the illegal population by half in five years. In the event, maybe the reduction will be only 30%, or maybe 70%. But we can be quite sure that such a strategy of "attrition through enforcement" will work in significantly reducing the illegal population — but only if we keep it up.

Mark Krikorian is executive director of the Center for Immigration Studies and author of the forthcoming book, "The New Case Against Immigration, Both Legal and Illegal" (Sentinel).

The great pull of economic forces

Dear Mark,

Good of you to acknowledge the humanity of undocumented immigrants. It's too bad you make unrealistic assumptions about the forces that shape their behavior.