I’m an advocate for extremely liberalized immigration policy. I’m hesitant about the using term “open borders” only because I don’t want anyone to assume I’ve signed on to someone else’s notion of open borders. But, yeah, I believe in mostly open borders. People who are dodgy about immigration think that an open immigration policy will swamp us with massive mobs of “the great unwashed.” All kinds of people will come here, the thinking goes, and degrade out culture, pollute our political institutions, take from our social safety net, and generally bother us at every turn. I want to argue that there is nothing to worry about.
For most of your day, you are ensconced in very exclusive private institutions. If you go to work, you are one among many employees who have been thoroughly vetted to work there. You probably spend most of your non-work hours at home. Here, you have an even more exclusive policy than you do at work. Even very good friends who have been thoroughly screened can only enter your palace for very limited times on your say-so. You surely have a locking door on your home, perhaps an even more sophisticated alarm system. Or maybe you live in an apartment complex with outside doors that are locked to non-residents, or a gated community that performs the same function for full-sized houses. Perhaps you go shopping for groceries and other necessities every week or so. Here you are protected by a store that, while far less selective than your employer or your home, will still throw out people who are rowdy or offensive to the other customers. If you go to a private club in your leisure time (as I do for jiujitsu class and as many parents do for their children’s after-school athletics and other activities), you are once again being protected by a private organization’s exclusivity policy, and you can extract yourself from anything that’s not exclusive enough to your liking. Without quite realizing it, you've constructed useful borders to keep undesirable people out of your life, and every institution you belong to helps you build these borders.
Even putting aside legal barriers to entry, think about what an immigrant needs to do to come here. He needs to convince an employer that he’s a good worker. He needs to convince a landlord to rent to him, or convince a bank to loan him the money to buy a house. You can’t just come here and sort of wander around and exist. You have to somehow connect yourself to the world through your housing and employment arrangements. To do that, you have to convince a few people who are already here that you’re worth dealing with. Merely getting into the country doesn't guarantee clear sailing. There are all kinds of border checks you have to pass once you get here, and if you fail them you don't get to work or acquire shelter or buy stuff.
Public property is a different matter. I'll grant that you are legitimately exposed when you travel on public property, because it is nearly impossible to exclude "undesirables." Anyone can enter public property. When you drive on public roads or enter public parks or walk on public sidewalks or shop in stores located on public squares, you expose yourself to people who haven't gone through any exclusionary vetting. Presumably if traffic safety becomes a serious issue, that can be solved with more thorough patrols of public roads and lower tolerance for reckless driving. And if crime becomes a problem in public places, it shouldn't be too difficult to increase the number of police officers patrolling those areas on foot. Granted you can't just preemptively exclude "undesirable" people from public property, you can certainly make them behave themselves by actively policing criminal behavior. Not that I think our public spaces will be swamped with "undesirables." I think this worry is totally overblown, but I felt a need to address it because there aren't enforceable borders around public spaces like there are for private spaces.
Incidentally, this is a kind of argument against public property. It's possible that some public spaces would better serve the public if they were made into private spaces, managed to maximize value for the users. Gatherings of rowdy teenagers can be told to "move along;" groups of brash, cat-calling men can be ushered out. People who aggressively panhandle can be banned from the premises. (I mean "aggressively panhandle" in a manner that invades people's personal space, which can be very frightening if you're walking alone.) Many people have an instant revulsion to the suggestion that we privatize anything currently owned by the government, but don't overlook this useful tool for dealing with social problems. Private spaces can be more thoroughly policed (or less thoroughly policed, if the public policing is excessive and obnoxious) than public spaces.
I suspect the discussion in the previous two paragraphs will be repulsive to some, because on a careless reading it looks like I'm arguing that immigrants in public spaces should be policed more thoroughly than everyone else. If that was your impression,please re-read, because you missed the point. My point was rather that it's more merciful to let them enter the country, conditional on their being more thoroughly scrutinized by police and private security, than to not let them come here at all. My overall point with this post is that problems of social decay and social disruption within immigrant communities (once again, a vastly overblown problem) can be solved or are already solved with private property. Or rather, if private property doesn't fully solve these problems, it at least keeps them from touching you. If there are "icky" people who you want to cordon off because you don't want to deal with them, you can mostly have your way. But I'd rather people do their own dirty work. Form your own exclusive private club or exclusive homeowners association. If you don't like the people you work with then quit, or suck it up and recognize that your co-workers have accepted these "undesirables" as colleagues. If people want to indulge anti-immigrant prejudices in their private lives, I don't really have a problem with that. But I don't want to be conscripted to enforce someone else's bigotry. Excluding immigrants shouldn't be public policy. It should be a privately enforced policy, and those people with anti-immigrant prejudices should personally pay the price of enforcing it. If an immigrant makes it here, it's because someone (an employer, a landlord, a spouse, a university) has accepted them. If you don't want to accept that person, that's fine, but you don't have the right to veto the decisions of those who have.
It's not the borders around the country that are keeping us safe and comfortable. It's mostly the borders within our borders that protect us.