A New Function: Borders as Membranes to Regulate Population Flows
(written by Lancelot Finn, September 2003 / December 2004)
The membrane is an analogy drawn from biology, and to introduce it, I hope the reader will pardon a digression into my favorite biology factoid.
Each living cell is surrounded by a membrane. The membrane is a miraculous molecular structure which contrives to be only two molecules thick! yet nevertheless is a cohesive structure which encloses and protects the cell. It is the cell’s skin, so to speak. The membrane is made of compounds called phospholipids. A phospholipid has a phosphate head, easily ionized and dissolved in water, and a fatty tail which, like grease, does not dissolve in water. Phospholipids naturally coalesce into bilayers, with the fatty tails drawing together but the ionized phosphate heads dissolving sticking out of the bilayer to dissolve in the water. Phospholipid bilayers compose most of the cell membrane, with more sophisticated proteins fixed in it to regulate the entry and exit of molecules desirable for the cell’s life.
Think of borders as bilayers, not of phospholipids, but of customs officials. There is one set of officials on each side of the border, regulating people’s entry and exit into the country.
Membranes regulate entry and exit in order to control the contents of the cell’s cytoplasm. The cytoplasm is the fluid interior of the cell, in which its organelles (cellular organs) float and perform various tasks that maintain the cell’s life. The organelles flourish best when the cytoplasm contains more and less of certain substances, and the job of the membrane is to make the cytoplasm most favorable to the organelles’ operation.
Think of population as a nation's cytoplasm. Organelles are a country’s institutions of all kinds, from Congress to Wal-Mart to the Boy Scouts, from churches to colleges to the New York Stock Exchange, from labor markets to people playing chess in the park on Saturday afternoons. The health of these institutions depends on the population. The composition of the population determines who gets elected to Congress, what products Wal-Mart decides to sell, what Eagle Scout projects get done; it fills the pews (or leaves them empty), staffs and studies at the universities, and votes by its investments which companies get the capital to expand; it bids wages for janitors and lawyers up or down. It may watch and applaud a favorite chessmaster. Or it may form gangs that scare away the chessplayers and make the park the scene of much more dangerous games.
What motivates border-membranes in their regulation of entry and exit? When the Romans built Hadrian’s Wall, their motive was to prevent invasion. When medieval Christian kingdoms expelled the Jews and prohibited their return, or when King Louis XIV of France expelled the Huguenots, the motive was to preserve a Christian realm characterized by unity of faith. What is the purpose of modern border restrictions?
A standard, realpolitik notion of the purpose of border restrictions is that on which George Borjas, in his book Heaven’s Door, bases his policy proposals. Borjas is writing about the United States, which faces issues in immigration policy that are parallel to those faced by other rich countries.
In my view, many participants in the immigration debate—although seldom saying so explicitly—have a particular weighting scheme [of the interest of natives, immigrants, and those left behind in source countries] in mind: the United States should be concerned only with the economic well-being of the native population.[1]
It is hardly just that citizens of rich countries should seek to maximize their own welfare at the expense of the freedom of migration of citizens of poorer countries. However, this result is not surprising, since democracy ensures that only those citizens are able to vote. Borjas concludes that it is in the United States’ interest to admit fewer immigrants, and immigrants with higher skill levels.
And this brings us back to the biology analogy. Cells tend to have high concentrations of nutrients, and therefore lower concentrations of water. Water cannot pass through the phospholipid bilayer itself, but proteins are fixed in the membrane to take in or expel molecules that the cell wants or does not want, and water can come in and out through these spaces. Since there is a higher concentration of water in the solution outside the cell than in the solution within it, the cell tends to absorb water and expand, which threatens to overstretch and burst the membrane. To combat this process, which is called osmosis, structures in the cell membrane have to steadily pump water back out of the cell.
To see how this applies to border-membranes, substitute the nutrients in the cytoplasm with wealth, and substitute water with people. Nations prefer to have a high proportion of wealth to people (i.e. per capita income). Rich nations enjoy just such a high ratio relative to poorer neighbors. This creates a tendency towards demographic osmosis, the migration of people from poorer countries into rich ones, which will tend to cause per capita income to move towards equality across countries. To prevent this osmosis and the accompanying reduction of per capita income, rich countries slow the influx of people and increase the influx of wealth. Wealth includes the human capital of skilled workers, since governments anticipate that these skills will soon translate into high productivity, high incomes and tax revenues. Which leads us to Borjas’s skills-favoring immigration policy.
Yet if it seems obvious that a self-interested wealthy citizenry would establish this kind of policy, think again.