We can disagree on placing a wall along our southern border, but only a fool argues a wall isn't an effective barrier to crossing over a land border.

Everybody knows that walls work to reduce trespassers. For some reason, there has developed a school of thought that claims walls don't work. Most of the people who make that claim know it is false. They would rather sound ridiculous to most people, create doubt with some people and keep from discussing the reasons why others believe a wall at the U.S.-Mexico border is necessary.

By claiming that a wall won't work on the border and that walls are actually a flawed idea for preventing trespassers, the open borders crowd avoids the discussion of illegal immigration in the United States.

Their argument that "walls don't work" is a rhetorical wall, and it is as effective in limiting discussion as a real wall is in preventing trespassers. The wall they have created in the discussion about the use of walls has delayed the passage of funding for a southern border wall. Their efforts have build mental walls in some people's minds about the concept of a simple wall.

Think about your own experience in life with the simple wall. I bet you have met a wall before; you have probably lived behind a wall. You may have even decided a wall would solve a problem, and then you funded and hired a contractor to build a wall for you. You may have gone so far as to participate in a government process to get your wall built.

If you have a pool in Massachusetts, you have a wall. If you live near a home that has a pool, you have experienced a wall. Is a wall around a pool offensive to you?

The Great Wall of China is something we all learned about in school as children. Tourists flock from around the world to visit the Great Wall of China. That wall is used in advertising campaigns every year. It isn't taught and visited and hailed in advertising because it is a failure. The Great Wall of China is a success, as most walls are at protecting the people who build it.

A wall isn't perfect. I used to jump over the wall at the concert arena then called Great Woods, now the Xfinity Center, in Mansfield. I saw Guns N' Roses, Stevie Ray Vaughn, Eric Clapton, Robert Plant and many more for free because I was willing and able to jump over the two walls meant to keep people out. Most people just did the right thing and bought a ticket to the concert. The walls worked for most people. If they didn't have a wall, people would have just walked across their border for free and the concert facility would have failed economically and vanished.

Walls work for pools and concerts—and countries.

Chris McCarthy is the host of The Chris McCarthy Show on 1420 WBSM New Bedford. He can be heard weekdays from 10 a.m. to noon. Contact him at chris.mccarthy@townsquaremedia.com and follow him on Twitter @Chris_topher_Mc. The opinions expressed in this commentary are solely those of the author.