We erect them everywhere around us for the purpose of protection and privacy.
The exterior walls of our home is strong to protect us from the weather outside. The interior walls of our home is intended to give us privacy or separation from other areas of the home. It is where we can escape for intimacy, solitude, and sometimes reflection...lowering our emotional walls. In our backyards, we sometimes build walls and fences to identify boundaries or for added security for our pets and children, so they don't run astray.
Since the introduction of the Information Age, we have created new walls to protect our government, businesses and personal data. The are called firewalls. In recent years, politicians have implemented legislation to break into these walls without probable cause. They give these legislations populous names like the Patriot and Freedom Acts. As to imply if you disagree, you are not a patriot or your not for freedom.
In recent politics, many conservative politicians (Rubio, Trump and Cruz) have described creating a physical wall that will be H-U-G-E and beautiful...to keep immigration under control. In years past (after 911), politicians wanted the walls down so they could lower wages and not have to pay a living wage. If they really wanted to control immigration, then why don't they create a "Legislative Wall" to highly penalize businesses that hire undocumented immigrants? This would be much cheaper and more humane.
Could it be that the failed policies of moving jobs offshore and opening the boarder to lower wages has angered Americans?
Could it be that the conservative politicians are creating an environment of bigotry against blacks, whites, latinos, asians (middle to lower income families) to deflect accountability away from their failed ideology? In other words, creating new walls between people, races and cultures...instead of paying respectable Living Wages, enacting immigration reform and providing a respectable path to US Citizenship?
People also create personal emotional walls to protect themselves from those that have hurt them or to keep personal thoughts and feeling private. When we trust people, some of those walls come down and we feel free to share our thoughts and feelings.
Do you want to build walls, live in fear, or do you want an environment of trust where walls come down and people and politicians share their real intentions?