The Economist reports that border enforcement costs the US $18 billion a year, more than all other federal criminal-law-enforcement agencies combined. On some stretches of the Mexican border enforcement it is reckoned to be only 30% effective, even given fences, drones, tower-mounted cameras and 21,000 patrol agents.

Were Epicurus alive today there is every likelihood that he would advocate the obvious: if, instead of wasting $18 billion on border enforcement you invested $10 billion in jobs/aid/improved living standards in central America you would keep potential Latino immigrants at home, do some actual good, and save the taxpayer $8 billion.

But then the whole immigration debate is not really about common sense.