I was thinking about this a couple days ago. It seems to me that stationing one or two police at schools would be more effective than this idea if we're interested in taking an active defense approach to stopping school shootings or minimizing their harm, though I hasten to add that they're a tiny fraction of total homicide and probably don't deserve this kind of attention.
My thinking is that uniformed officials with the weight of authority behind them would probably have a more salient deterrent effect than whatever armed schoolteachers would imply, and also that forging non-confrontational links between police forces and civilians would have substantial positive externalities. Though this latter would depend greatly on style; a scare-'em-straight approach might backfire, and I'm almost sure that using cops purely as glorified security guards would. Arming and training teachers might put shooters down faster, but I can't see much deterrence or any substantial externalities, and it would be an expensive program.
Though on the other hand I don't see many negative externalities either; last time I looked at data on shootings (accident and murder inclusive) attending trained and licensed bearers of firearms, the rates turned out to be quite low.
Some schools already do this. My high school, for instance. But that was a school with a particularly low level of threat to begin with. Not that there was never any crime for him to deal with even in a well off suburban school; the worst case I ever heard about him having to deal with was a stolen laptop.
I don't know how to keep this topic away from http://lesswrong.com/lw/gw/politics_is_the_mindkiller/ , so I'm just going to exhort everyone to try to keep this about rationality and not about politics as usual. I myself have strong opinions here, which I'm deliberately squelching.
So I got to thinking about the issue of gun control in the wake of a recent school shooting in the US, specifically from the POV of minimizing presumed-innocents getting randomly shot. Please limit discussion to that *specific* issue, or we'll be here all year.
My question is not so much "Is strict gun control or lots of guns better for us [in the sole context of minimizing presumed-innocents getting randomly shot]?", although I'm certainly interested in knowing the answer to that, but I think if that was answerable we as a culture wouldn't still be arguing about it.
Let's try a different question, though: how would we know?
That is, what non-magical statistical evidence could someone give that would actually settle the question reasonably well (let's say, at about the same level as "smoking causes cancer", or so)?
As a first pass I looked at http://en.wikipedia.org/wiki/List_of_countries_by_intentional_homicide_rate and http://en.wikipedia.org/wiki/List_of_countries_by_firearm-related_death_rate and I noted that the US, which is famously kind of all about the guns, has significantly higher rates than other first-world countries. I had gone into this with a deliberate desire to win, in the less wrong sense, so I accepted that this strongly speaks against my personal beliefs (my default stance is that all teachers should have concealed carry permits and mandatory shooting range time requirements), and was about to update (well, utterly obliterate) those beliefs, when I went "Now, hold on. In the context of first world countries, the US has relatively lax gun control, and we seem to rather enjoy killing each other. How do I know those are causally related, though? Is it not just as likely that, for example, we have all the homicidally crazy people, and that that leads to both of those things? It doesn't seem to be the case that, say, in the UK, you have large-scale secret hoarding of guns; if that was the case, they'd be closer to use in gun-related homicides, I would think. But just because it didn't happen in the UK doesn't mean it wouldn't happen here."
At that point I realized that I don't know, even in theory, how to tell what the answer to my question is, or what evidence would be strong evidence for one position or the other. I am not strong enough as a rationalist or a statistician.
So, I thought I'd ask LW, which is full of people better at those things than I am. :)
Have at.
-Robin