Megan McArdle asks, "Are Guns at Protests Really Dangerous?" in order to argue that they aren't:

I think carrying guns to protests is entirely counterproductive.  Indeed, I'm not sold on the general virtues of protesting, which worked for Gandhi and the civil rights marcher, but has a dismal track record on other concerns.  But I think people have a perfect right to do it, including with guns, though I also think the secret service is within its rights to ensure that they don't have a sight line on the president.

But the hysteria about them has been even more ludicrous.  Numerous people claim to believe that this makes it likely, even certain, that someone will shoot at the president.  This is very silly, because the president is not anywhere most of the gun-toting protesters, who have showed up at all sorts of events.  It is, I suppose, more plausible to believe that they might take a shot at someone else.  But not very plausible:  the rate of crime associated with legal gun possession or carrying seems to be very low.  Guns, it turn out, do not turn ordinary people into murderers.  They make murderers more effective.

This is very silly. Look, just on a basic level, the Secret Service's capacities aren't infinite: protecting the president is hard enough in normal circumstances; throw in the job of making sure gun-toting protestors don't have a sight line on the president, and the agents' jobs become that much more difficult. Even if the gun-toting protestors whose rights McArdle is defending pose no harm to Obama, keeping a constant eye on them takes up resources--resources the Secret Service might need to thwart people who do mean to do harm to the president.

Then McArdle goes from silly to offensive, writing:

So perhaps unsurprisingly, when offered the opportunity to put some money down on the proposition that one of these firearms is soon going to be discharged at someone, they all decline.

Or maybe they just have enough basic decency not to wager on whether or not Obama--or anyone else, for that matter--is going to get shot.