Everybody wants to keep children safe in school. That, I hope, is a given. President Trump wants that. Democrats want that. Republicans want that. The NRA wants that, too. But the added tragedy of America's unique rash of school shootings is that, no matter how sad and angry and sickened everybody is after a slaughter of innocents, the federal government keeps doing nothing.

Well, not nothing, exactly — in September 2004, five years and five months after the murder of 12 students and one teacher at Columbine High School in Colorado, the Republican-led Congress let the Federal Assault Weapons Ban expire. Four years later, in 2008, the conservative majority on the Supreme Court ruled for the first time that the Second Amendment guarantees an individual right to own firearms, not just in a well-regulated militia. On the state level, Republican-led governments have loosened gun laws and Democratic-led states have tightened them, to the extent allowed.

After the murder of 14 teenagers and three adults at Florida's Marjory Stoneman Douglas High School last week, the hot new alternative to gun control is fortifying — or, rather, fortress-ifying — America's schools. More specifically, Trump's big idea is to encourage 10-40 percent of American K-12 teachers to carry a concealed firearm to school, and to advertise that fact to deter shooters. The NRA approves of this idea — more guns in schools means more guns, gun owners, and gun sales, after all. And as the argument goes, nothing stops a bad guy with a gun as effectively as a good guy with a gun. (It should be noted, however, that the armed guard at Stoneman Douglas High did not stop the bad guy with a gun.)

There are a lot of reasons why arming teachers could be a bad idea: cost, logistics, risk of deadly accidents or theft, added pressure for people whose testing-fueled job is already stressful enough. But it would also completely change the modern idea of childhood. Are we ready to do that in order to preserve the easy accessibility of unnecessarily powerful, unreasonably rapid-fire firearms?

We could choose to keep children safe — we know how. There are very few "prison shootings," for example. America could retrofit schools with metal detectors in their one unlocked entryway, with armed security officers screening K-12 students as they show up for school. We could put bars over bulletproof-glass windows. Hell, we could build alligator-filled moats around schools or put them behind barbed-wire fences — that would certainly cut down on hooky-playing.

And there is a certain appeal in the idea that, once you drop your children off at Fortress Academe and they make it through TSA-like security, you don't have to worry about them until pickup. We give up convenience to feel safer in airports and on airplanes, after all, and our concern for the safety of every child can be seen in the peanut bans many schools have enacted.

But protecting people with peanut allergies is much closer to the modern ideal of childhood than locking them up for eight hours a day, even as safety-obsessed as American parents have become over the past 30 years. Because more than anything, what we strive to protect today is a child's innocence and sense of safety, and guards or teachers with guns shatter that illusion pretty quickly.

Trump seems to get that. He told officials at the White House on Thursday that "active shooter drills is [sic] a very negative thing," because they are "crazy" and "very hard on children." He added: "I don't like it. I'd much rather have a hardened school." (White House spokesman Raj Shah clarified that Trump only opposes "the term 'active shooter drills'" because "the brand of it" might "be frightening for young children.") Trump also opposed the idea of posting armed guards in schools, for a similar reason: "It would look bad — you know, if you have guards, it looks like you have an armed camp, that would look terrible."

Knowing that a teacher is or may be packing heat is probably even more unsettling for students.

By most metrics — mass shootings are a glaring exception — being a child in America today is safer than ever. And partly because of that, childhood lasts longer than it used to, in most ways. The days of coming home from school, picking up your hunting rifle (and maybe a pack of cigarettes), and walking through the woods or prairie until dinnertime are mostly stuff of nostalgic fiction now. Child labor has been relegated to scattered farmwork and foreign countries, and car seats and bike helmets are legally required or at least expected. Modern medicine has made once-deadly ailments fixable.

Ironically, the modern idea of hallowed childhood is the beating heart of the renewed push for more stringent gun laws. The teenagers who survived the shooting at Marjory Stoneman Douglas High School have a moral authority largely derived from the fact that their childhood was violated.

Now the options are to preserve childhood or preserve a maximalist interpretation of the Second Amendment that says it is a God-given right for every American 18 and older to purchase a military weapon. Which side wins is anyone's guess.