Welcome to elementary school. No sooner had the bullets stopped flying at Sandy Hook last week than those who favor unlimited access to military-grade assault weapons began advancing one of their favorite theories:

If only folks at the elementary school had been armed, that crazy kid would have been popped in the head before he shot anyone.

(Anyone, presumably, except for the kid's mother, whom he shot twice in the head before he left her house with her guns.)

Republican Representative Louie Gohmert, for example, went on FOX News this weekend to deliver exactly that message:

"I wish to God [Sandy Hook principal Dawn Hochsprung] had an M-4 in her office locked up — so when she heard gunfire, she pulls it out and she didn’t have to lunge heroically with nothing in her hands...But she takes him out, takes his head off, before he can kill those precious kids."

This is a common argument and a common fantasy: If the "good guys" also have assault weapons, they'll take out the "bad guys."

It is also completely insane.

It would likely lead to thousands more gun-related deaths every year (of good guys, not just bad guys). And it would also turn America into an armed police state in which hundreds of millions of normal citizens had to act and feel like they might be shot by anyone at any moment — and conduct themselves accordingly.

It is a very common argument, though, so let's play it out.

First, let's think about exactly the scenario Gohmert laid out.

"I wish to God [Sandy Hook principal Dawn Hochsprung] had an M-4 in her office locked up..."

Based on the detailed account of the shooting written by a team at the Hartford Courant, if Dawn Hochsprung had had "an M-4 in her office locked up," it wouldn't have helped her. Hochsprung was in a conference room in a meeting when Adam Lanza shot his way through the door. An assault rifle "locked up" in an "office" isn't a particularly effect killing tool when it isn't handy.

Dawn Hochsprung, shot and killed last week. via ABC News Also, in the more detailed accounts of the massacre, Hochsprung did not "lunge at " Lanza empty-handed to try to stop him. Rather, it appears, she burst out of the conference room to see what on earth was going on. Lanza was clearly ready for this and shot and killed her so fast that she may not have even had time to process what was happening.

But maybe what Gohmert meant is that he thinks Hochsprung should have taken the M-4 out of its locked case every morning, strapped it on her back like an old-time bandillero (along with ammo belts), and worn it around the school every day.

If Hochsprung had done that, she would have least have had the weapon with her when Lanza blew away the front door.

Of course, Lanza wasn't an idiot.

He planned the attack carefully.

He was wearing a bullet-proof vest.

And if Lanza had been attacking a school in which it was known that the principal carried an assault weapon around, he presumably would have been ready to be shot at. He might not have burst through the door the way he did. He might have shot through the windows. Or he might have figured out where the principal was likely to be and made sure he took her out before she took him out. (Bad guys know how to fight, too).

So, let's assume that if part of Hochsprung's job were to protect the school from an armed assault, she would have to be trained in counter-attack tactics. She would have wanted to wear body armor. She would have wanted to clean and fire her M-4 regularly, to make sure it was ready to go at a second's notice in the highly highly unlikely event that the school was attacked. And she would have somehow trained herself to remain on high alert every hour of every day for all the years and decades that she worked as a teacher and administrator, all the while also being an excellent educator and manager.

And then, the morning of the attack, Hochsprung would have had to have reacted perfectly — hearing the gunfire and shattered glass from her conference room, unslinging the M-4, releasing the safety, crawling silently toward the door of the conference room, and then taking aim at a highly alert gunman and shooting him in the head before the gunman noticed that she was there or had fired a single bullet at anyone.

(In other words, she would have to assassinate Adam Lanza on the assumption that he was there to kill kids, and not wait for him to do it. Or was she supposed to wait for him to kill someone, on the theory that he might just be a dime-a-dozen crazy person who didn't actually intend to kill anyone? There are lots of those, too.)

In other words, Hochsprung would have had to have acted and reacted like a soldier in a war zone. All day. Every day. For decades.

And what if Hochsprung had been on the other side of the building when the attacker shot through the door? Principals do, occasionally, leave the vicinity of the front door.

Just another day at Walmart in an Armed America. Gavin Aronsen via Twitter Well, to eliminate that risk, Gohmert and others who want to keep giving almost all citizens unlimited access to military weapons will presumably want to arm every teacher and employee at the school. So they'll all walk around all day with M-4s and bullets strapped to their shoulders. And they will all have to be trained and act and react in precisely the same way — all without someone ever making a mistake and shooting a kid instead of a bad guy.

If Gohmert really wants his kids to go to an elementary school like that — if he thinks his kids will be "safer" there than at a normal school — he's certainly entitled to think that.

I personally think his kids will be in much greater danger of getting shot and killed in that school (probably by accident — a gun goes off, a kid grabs a gun and fires it as a "joke", etc.) than they would in a normal school. And I think it's a sick, insane vision of what is otherwise supposed to be a highly civilized country. But we're all entitled to our opinions, and if Gohmert wants to live in a police state, he can.

Of course, if we're going to arm everyone who works in schools with M-4s, we're probably going to want to arm everyone who works or goes to any other place that someone might open fire: malls, theaters, parks, arenas, stores, streets, etc.

(Lots of people go to Walmart. Do we really want to take the risk that some nut-case is going to barge in there and start shooting people? Of course not. We should have every Walmart employee carry an M-4.)

We'd be much safer if everyone had one! (Not.) Academy And when we're finished arming all of those people, everyone else pretty much will have to carry a locked and loaded M-4 in this country to feel even remotely safe. Lots of those guns will just "go off" a lot, of course — because that's what guns occasionally do. And lots of kids will pick up the guns and accidentally shoot themselves, their siblings, their parents, and their friends because that's what kids sometimes do when loaded guns are left lying around. And when we're in a public place and someone starts acting weird, we might want to just pop them in the head just to be sure, because, you know, you never can tell when someone's just going to open fire. And lots of people will of course be dropped in the resulting crossfire.

The idea that we can reduce gun-related deaths and mass shootings in this country by arming everyone is a fantasy. In some respects, it is even a pleasant fantasy. It takes us back to our "wild west" roots and makes us feel empowered and righteous — a nation of Clint Eastwoods and Marlboro Men who always get the bad guys. It takes us back to our childhoods, in which "good guys" and "bad guys" could shoot it out all afternoon, and the "good guys" always won.

It's a pleasant fantasy. But it's a fantasy.

And it's time we outgrew it.

SEE ALSO: I'm Just Not Ready To Accept That We Have To Have Mass Shootings All The Time