I see this argument thrown around a lot on reddit, and I think people generally look at "no-gun zones" the wrong way. Obviously someone with the intent on shooting up a school or mall will pay no attention to a sign, but then again, that's not really the point. We don't rely on signs to stop murderers: we have laws and a justice system and law enforcement officers whose job it is to prevent and respond to people who do that kind of thing.

The signs are more about making the people in those areas feel safe and help easily identify who should have a gun and who shouldn't.

Take a school, for example. Open/closed carry laws are notoriously complicated and vary wildly from place to place. Now let's imagine you're an 8 year old, for whom remembering how to tie their shoe is a difficult daily task. If you're that eight year old and you see someone who clearly isn't a police officer carrying a pistol on his hip, what are you supposed to think? You certainly have no idea if that guy is trustworthy or if they are a parent or a staff member or just some random dude who wandered onto the playground. You may never have seen a civilian with a gun... hell, you may not have ever seen a gun outside of a movie. You have no idea if you should tell a teacher, go about your day, or hide. Consider that all it takes is one student (or faculty member) to freak out, and suddenly that guy -- who may have been completely benign and well within his rights -- has set off all kinds of alarms, none of which, in the post-Columbine world, are taken lightly.

All of this is a recipe for panic, and it's all completely and totally avoided by letting everyone know as soon as they walk on the premises that you're not allowed to have a gun here. It sets clear guidelines for everyone and lets places like schools and malls set a clear and standard procedure for if/when someone does show up armed. The almost ironic thing is, by putting up that sign, you actually make it easier for people to spot a terrorist or school shooter, because, well, they have a gun where they're obviously not supposed to.

Now, it's easy to say, "well, that's everyone else's problem... I'm within my rights..." and I feel you on that. And sure, there are places where people can open carry anything they want and the public doesn't freak out. But, as we've established in countless other cases, sometimes your constitutional rights have to be limited for the sake of public safety and tranquility.

And while it's also tempting to argue that these zones only provide a false sense of security, events like school shootings and terrorist attacks -- despite being big news -- really are extremely rare occurrences in the U.S.. So at some point you are throwing out a system that, for all intents and purposes, seems to work just fine in the vast, vast, vast, majority of cases.