I've fallen victim to one of the classic blunders, right after never going in against a Sicilian when death is on the line, which is: don't get into an argument with a libertarian about anything, really, but especially about guns. But, alas I have, so I'll go one more round on this with Megan McArdle (and her tag-team partner Will Wilkinson) and then I promise I'll be done.

McArdle writes:

Jason Zengerle indicates that the real point is that openly carrying weapons at a protest makes it harder for the Secret Service to do their job.  Probably.  On the other hand, lots of things make it harder for the Secret Service to do their job.  Protesting is much harder on the Secret Service--almost certainly harder than one guy openly carrying a gun, because the protesters are a crowd of people who have to be watched constantly for suspicious movements.  Should we ban protesting?  Or force the people who do it off the premises and into a park eight blocks away?

Meanwhile, Wilkinson weighs in with this similar point:

The silliest thing is Zengerle’s casual assumption that if the free and peaceful exercise of an enumerated constitutional right “takes up resources,” then the state may therefore limit it. I doubt he’d like to generalize this principle. Of course, the real issue is likely that Zengerle is not impressed with the idea of an individual right to bear arms. So he’s untroubled by limiting it on the grounds that it might cost a little money or slightly affect the probability of harm to the president.

But the thing is, when it comes to the protection of the president, the state does limit the free and peaceful exercise of an otherwise enumerated constitutional right. To wit, while I won't get a knock on my door for writing on the Internet that I want to harm Joe Blow, I will if I write that about the president. I don't want to ban protesting, I don't want to ban free speech. But it just seems like basic common sense that we not allow people with guns in close proximity to the president. I'll leave it at that.