Keep, ancient lands, your storied pomp!” cries she
With silent lips. “Give me your tired, your poor,
Your huddled masses yearning to breathe free,
The wretched refuse of your teeming shore.
Send these, the homeless, tempest-tost to me,
I lift my lamp beside the golden door! 

Emma Lazarus’s poem “The New Colossus” is stirring poetry. Unfortunately, great poems are not a substitute for legislation.

The debate on immigration in America has hit a wall. “Debate” is the wrong word, though, with its implication that the two sides are actually speaking to one another and addressing the arguments of the other. It is more accurate to say that the posturing on immigration has hit a wall.

Types of Immigration

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Before we can proceed, we need to agree on the answer to a question. When we talk about immigration, what exactly is it that we are discussing?

You would think that it is obvious what this discussion is about. Immigration is people moving to your country. But that definition masks the fact that there are actually many, quite distinct, categories of people who fall under the broad definition.

For example, consider the following questions:

1) Is the immigration permanent or temporary?
2) Is the immigrant moving for the purpose of becoming employed or for some other reason (say, to enroll in college or to be with family)?
3) Is the immigration legal or illegal?

Those three questions alone give us eight separate groups of immigrants. There are, of course many more questions like that we could add. But, consider for a moment just those eight categories. In order to believe that people in those eight categories should all be treated the same way, one must believe either

1) there should be zero migration between countries, or
2) there should be zero restrictions on migration between countries.

There are very few people who fall into either of those extremes. Similarly, very few people believe a person on a legal, temporary work visa is the same as someone illegally settling permanently in the country for non-work-related reasons.

American immigration law reflects the varied purposes for which an immigrant might move to the United States. Surprisingly, it is actually not very easy to find out how many different visa types exist. One attempt to count came up with “about” 185 different types.

The lack of clarity on what exactly we mean when we say the word “immigrant” creates an obvious problem. Not everyone in the discussion is talking about the same thing. However, even if we could all agree about what type of immigration we are discussing, there is a more fundamental problem. What is the goal?

Consider this question: if the decision were entirely up to you, how many legal immigrants would you allow to settle permanently in the United States in a given year? You probably don’t have an exact number in mind, but think of a round number.

And after you answer that: how many permanent legal immigrants are currently allowed to settle in the United States in a given year?

Now, a third question: is the current level of legal immigration too high or too low?

Finally, be honest: was the third question easier to answer than either of the first two questions?

Illegal Immigration

It is safe to say that most of the discussion about immigration in America is not, and has not been, strictly about legal immigration. One side of the discussion says that illegal immigration should be eliminated and discusses the costs of immigration, making no distinction between legal and illegal, permanent and temporary. The other side talks about the benefits of immigration, argues that we should stop trying to curtail immigration, but also makes no distinction between legal and illegal, permanent and temporary.

This situation is not new. For decades, virtually every major legislative act has focused on illegal immigration. The effects on legal immigration have been a by-product, almost an afterthought. It has been a very long time since Americans had a frank, informed debate about legal immigration.

So how large is illegal immigration? For obvious reasons, it is quite difficult to get precise numbers on its size or composition. The most commonly cited guesses put the number of people who are currently living in the US without legal authorization at around 11 to 12 million, or somewhere between 3 and 4 percent of the US population. Those numbers are based on survey data, however, which we know is not the best means to gauge the amount of illegal activity. Researchers at MIT and Yale used a different method to come up with an estimate of around 22 million, or between 6 and 7 percent of the population.

Looking at those numbers, it is not hard to understand why the focus has been on illegal rather than legal immigration. Figuring out the proper size and composition of legal immigration is hard. It seems much easier to debate this question: How large should illegal immigration be? What is the optimal number of illegal immigrants per year?

The question seems absurd. It seems hard to think of any reason at all to give an answer other than zero. People do—at least implicitly—give numbers other than zero, however. This makes sense when you realize that when people are talking about illegal immigration, what they are really arguing about is the size of legal immigration.

Suppose you think that the number of legal immigrants is too low, that the country would benefit from a higher level of immigration. In that case, illegal immigration does not seem like a terrible thing; it is the easiest means to get the number of immigrants up to the desired level. On the other hand, if you think the number of legal immigrants is too high, then it is obvious that the number of illegal immigrants should be reduced as well.

Why the Immigration Debate Has Been Unproductive

When one side of a debate says we need to limit the number of people illegally residing in the country and the other side responds by saying that we need more highly trained legal immigrants, it is no wonder that the debate never gets anywhere. If this is right, if we are ever going to have a meaningful discussion about immigration, we first need to have a discussion about the optimal number of legal immigrants.

As promised, here is the number: according to the Department of Homeland Security, in 2017 (the most recent year for which the data have been released) the number of people obtaining lawful permanent resident status was 1,127,167.

Now that you have seen the number, your likely reaction is that you have no idea how to interpret it in a meaningful manner. Is that a high or a low number of immigrants? In order to answer that, you would need a standard of comparison.

That standard of comparison is exactly what is lacking in the current immigration debate. Without it, it is literally impossible to have a substantive discussion about immigration. How do we determine the right level of immigration? Assuming the optimal number of immigrants per year is neither zero nor infinite, what is it? Five hundred thousand? One million? Two million? Five million?

There is also another, perhaps deeper, rhetorical problem. Consider the following: “I would like lower or constant levels of legal immigration and I oppose illegal immigration. But of course my mom should be allowed to immigrate.”

The problem with much of the rhetoric surrounding lowering legal or illegal immigration is that it does indeed sound like an argument for deporting someone’s mom, and maybe even your own mom. The problem with much of the rhetoric surrounding arguments against doing anything to reduce illegal or legal immigration is that it does sound like an argument for having absolutely no restrictions on who should be allowed to permanently settle in the country.

A Path Forward

Thus, we not only need to change the substantive starting point for the discussion on immigration, we also need to find a new rhetoric.

The substantive challenge is easier. The obvious starting place is to look at the economics of immigration. Here, the evidence is very clear. For the country to which the immigrants are moving, there are both costs and benefits. In the aggregate, they are about equal to one another. There are distributional effects that I will discuss in a subsequent essay. But, there is no net aggregate economic benefit or cost from immigration.

That conclusion comes as a shock to just about everyone who is not well-versed in the economic literature. In the public discussion, those who favor higher levels of immigration cite only the very real benefits of immigration. Those who favor lower levels of immigration cite only the very real costs of immigration. Since it is quite easy to read only things with which you agree, most people have no idea about the other side of the literature.

If the debate on immigration is thus not an economic debate, what is it? A cultural debate. What kind of a nation are we? If you are like most people, that question just caused your rhetorical defense mechanisms to go up. So, to make progress in the discussion, we need some way to defuse the rhetoric.

One option is presented in Paul Collier’s excellent book, Exodus: How Migration is Changing our World. In it, Collier lays out a simple model that can be used to think about the matter. Collier’s model looks at the size of the diaspora, the immigrant community in a country. Obviously, the diaspora increases in size as more people immigrate into the country. However, the diaspora decreases in size as, for example, people marry outside of the immigrant community and become assimilated with the larger population.

Comparing the inflow of immigrants to the outflow from assimilation instantly tells you whether the diaspora is rising or falling. Because those inflows and outflows are affected by the size of the diaspora, there are many possible points where the size of the diaspora will stabilize. However, there are also tipping points in both directions that will not result in a stable diaspora. If the inflow from immigration is small enough relative to assimilation, over time the diaspora will vanish. If the inflow of immigration is large enough relative to assimilation, the diaspora will increase without bound.

The question is thus not about whether a country should have zero or infinite immigration, but where the tipping points are. The short answer is that we simply do not know. Those tipping points matter, however.

There are conflicting American narratives. We are a nation with a shared set of ideals, and we are a nation of immigrants. America can only maintain both of those narratives if the level of immigration does not cross the tipping point in either direction. If immigration gets too low, then America will lose its much beloved self-image as the haven for the huddled masses yearning to be free. If immigration gets too high, then America will lose its much beloved self-image that we are people e pluribus unum, out of many, one.

Framing the question this way does give us a way to reset the immigration debate. If we all agree that we want to preserve both of these aspects of the American national culture, then we can start our discussion about immigration from this shared set of ideals and begin the laborious task of determining the levels and types of immigration that will allow the continuation of the American experiment. We are all acknowledging that there is a finite size of legal immigration that is desirable, and the discussion is simply about how large we want the diaspora to be. We are then at least talking about the same thing.

However, without a radical change to the rhetorical nature of the debate on immigration, it is impossible to conduct a discussion on the desirable levels of legal immigration. Sometimes, short-term political gains from heated rhetoric get in the way of long-term discussions about the future.