This is definitely not my topic of research. So you may very well ask why would I venture to wrote about it, beyond the obvious reason that it is probably one of the most debated issues these days in the US, with the government shutdown being related to the now infamous wall. I am myself twice an immigrant, I descend from immigrants (my parents returned to their country of origin, but had emigrated, and on my mother side my grandfather was also an immigrant, and the same goes on my father's side a few generations before), I might add. But that is not the whole, or the most relevant, reason.Most debates about immigration center on labor market issues, and discuss the issue analytically with the tools of marginalism. The conclusions, by definition, are the logical consequence of the
Matias Vernengo considers the following as important: Capital Controversy, immigration, neoclassical economics, Surplus Approach
This could be interesting, too:
Michael Stephens writes Bad Faith and the US Census
Edward Harrison writes The border wall and the Fed’s reaction function
Mike Norman writes James Pethokoukis — Republicans have a big new economic idea. It’s terrible.
Most debates about immigration center on labor market issues, and discuss the issue analytically with the tools of marginalism. The conclusions, by definition, are the logical consequence of the assumptions in that model, and the reading of the evidence is biased by those theoretical concepts. Here is a place were the capital debates (go read this very old post) might be important for a policy issue that is in the news constantly and that should concern economists. Being in favor of a return to the old and forgotten method of classical political economy, or the surplus approach, and not having seen any discussion of the issue along those lines is what led me to write this brief post.
Let me start with a very simple representation of the conventional argument. In the conventional story, you have a market for factors of production (labor in this case), and equilibrium is obtained when the marginal productivity of labor equals the marginal disutility of labor, where firms maximizing profits and individual workers maximizing utility find the optimal solution, shown in point C in the figure below (with variables with their traditional meanings; note I use N for labor, since I leave L, for liquidity; yep, I still teach the ISLM with that pesky L in there).
In this case, the effects of immigration are relatively simple to understand. Mainstream economics suggests that immigrants would add to the labor force, increase the labor supply, reduce the real wage, and lead to firms hiring more workers and increasing production. Output and employment should go up, while real wages would go down. The effect on the wage bill (W/p * N) depends on certain assumptions, but certainly native workers lose to the extent that their real wages go down. Hence, a backlash against immigration by working class native groups should be expected.
This simple analysis abstracts lots of things, of course. Differences in the quality (skills) of workers, and immigrants, and what would happen in the presence of capital mobility (with profits going up, with lower real wages, and capital mobility, then new factories should move into the country to take advantage of lower wages and increase the demand for labor, eliminating any initial effects on real wages). A lot of the academic debate has been based on arguments along these lines (see, for example, the Card and Borjas debate on the effects of the Marielitos Cuban immigrants in Miami real wages in this nice Vox post). Note, also, that the evidence suggests that the effects of immigration on real wages of unskilled workers are relatively small (if you believe Card).
In this view, then, there are some acceptable reasons for workers to be concerned with immigration. Note that this says nothing about fiscal issues, which many conservatives also use against immigration, suggesting incorrectly that they do not pay taxes (they certainly pay sales taxes, and other local taxes, and given the low incomes of most unskilled workers, would not qualify for income tax anyway), and take advantage of public goods. However, there are many analytical problems with the assumptions of the model above.
Note that the basis of the marginalist (or neoclassical) model presented above is the principle of substitution. In other words, as labor becomes cheaper than capital, that is by assumption fully utilized, then firms hire more labor. So the lower wages guarantee the full utilization of labor. The intensity of labor increases as its remuneration falls, and the price of labor, as any other price in marginalist theories (Austrian too, although they sometimes confuse this) reflects the relative scarcity of the factor of production. Note that for classical political economy authors (including Adam Smith) real wages resulted from historical and institutional factors, and supply and demand were only one of the factors affecting them. Under the conditions they analyzed the economies of their time they assumed that real wages were essentially at subsistence level.
The capital debates become relevant because they essentially show that the substitution principle has logical problems, and they open the possibility to a return of the sort of historical and institutional analysis of the labor market of classical political economics. I will not discuss the whole issue here again (check that post linked above), but the essence of the argument is that sometimes when real wages go down instead of leading to firms hiring more workers, the opposite might occur. Think of a situation in which real wages fall, and as a result, there is less demand for the goods produced by the firm. Perhaps the firms goods are bought by workers themselves. Even though labor is cheaper, there is no reason for the firm to hire more workers if they cannot sell their goods, and the income effect overwhelms the substitution effect (the capital debates suggest that the substitution effect may go in the wrong direction, on top of that). That's essentially what Keynes said on chapter 19 of the General Theory (in chapter 2 he basically accepts the marginalist demand curve above, which is problematic, and shows the limitations of the supply curve; my paper on reading Keynes after Sraffa, the key author of the capital controversy, here).
The point is that it cannot be guaranteed that immigration would lead to a reduction of real wages, at least not on the basis of the logic of the model above. The actual result is ambiguous. Classical political economy provides an alternative framework to look at the labor market effects of immigration. It is clear that an increase of the labor supply might affect negatively the bargaining power of the established workers. But note that this is not always necessarily the case. Arguably, in the case of many immigrants in the so-called first globalization (late 19th to early 20th century), in which significant amounts of Socialists and Anarchists from Eastern and Southern Europe came to the US (and other parts of the Americas), the effect was to raise the class consciousness and the combativeness of the working class, helping strengthen some unions.
And the reverse is true, a country that experiences emigration might actually lose key workers, and unionization rates might decrease. In the last 30 years or so, the US has experienced an increase in the population of immigrants, many came from Mexico of course, and yet both countries have experienced a decrease in unionization rates (see here for Mexico). This suggests that other forces are in action, and that wage stagnation might be related to those policies, and not just, or not even fundamentally, as a result of the flows of workers from one country to the other.
Note also that classical political economy authors assumed that output was given in their discussion of distribution, and that separation of the theories of output and employment (dominated by Ricardian Say's Law, that was not a necessary feature of classical thinking, and that can be superseded by the Keynesian Principle of Effective Demand) allows us to understand other aspects of immigration. In other words, the level of output and employment would depend on autonomous spending (demand), and immigrants can easily be accommodated in society without displacing the native workers. Of course that would depend to a great extent on the government macroeconomic policies (not just fiscal and monetary policy, but also the setting of minimum wages, industrial and trade policy and so on).
In this view, it is less the effects of immigration on the labor market (along neoclassical lines of reducing real wages and increasing employment) that matter. It has been the policies that actually led to lower growth, lower union participation, trade policies that favored the loss of manufacturing jobs that have created the conditions for real wage stagnation. In that sense, it is those policies that are responsible for the backlash against immigrants among large groups of resident (native) workers, that could be exploited politically by right-wing populists, often with fascistic and authoritarian tendencies (not just in the US). Immigrants are actually escaping from similar neoliberal policies in their countries of origin.
And all of these points are just about the most direct economic consequences of immigration. There are other issues that are as relevant beyond economics. And it goes without saying that both immigrants and refugees (in particular those that result from US direct or indirect intervention abroad) deserve humane treatment, even if the conventional mainstream story was correct and immigration did cause inequality.