From a recent op-ed: For five millennia, politicians have proposed walls like Trump’s. They don’t work.  From The Washington Post, Sunday July 29, 2016.

The opening:

Donald Trump’s proposal to build a wall along the border between the United States and Mexico to block the flow of migrants has been justly criticized on moral, economic and political grounds. But while the Trump Wall (as he has called it) is the most provocative proposal of the election season, it is not particularly original. Over the past five millennia, politicians have repeatedly turned to large walls to solve problems. We should look carefully at the track record of this ancient technology before we invest what some estimates suggest could be $25 billion in construction costs for a 2,000-mile-long wall, plus millions more in annual maintenance.

And the conclusion:

What is most captivating about barrier walls, like the Trump Wall, is neither the scope of their construction nor the resoluteness of their strategic vision. Rather, they are powerful symbols of a particular kind of hubris, the conceit that the translation of mania into masonry can alter the decisions, fortunes and futures of countless others through architectural intimidation. Here, the Berlin Wall should still live in all of our memories as a potent symbol of how walls and totalitarian politics often find common cause. Barrier walls are not simply clumsy, imprecise solutions to problems of population movement, past and present; they also represent a catastrophic failure of political imagination endemic to totalitarian thinking.

Click on the link above for the full op-ed.