Having spent the better part of a week asking teachers why they'd risk a public backlash by going on strike, I've concluded that the answer is best summed up by what one told me at their Labor Day rally: "Mayor Emanuel's pushed us to the limit. He's the world's biggest asshole."

Actually, I think he may have dropped the F-bomb once—or twice. But I'm trying to clean things up since this is a family newspaper, dammit!

But here's the bottom line: so much of this fight is fueled by the animosity of thousands of teachers toward one man.

I know—I shouldn't joke. A teachers' strike is serious stuff: the lives, careers, and future plans of thousands of teachers, kids, and parents are at stake.

I just read an open letter "To the Leaders of the Chicago Teachers Union from Leaders of the Faith Community." It's an ad in the Sun-Times, published before the strike and signed by various clergymen with close ties to the city government, calling on teachers to do what's right for the kids and call off their strike.

"We do not side with the Mayor, the Chicago Public Schools, or your organization," the letter reads. "We side with the 350,000 students who will be placed in harm's way if you lead Chicago teachers into a strike."

Of course, by writing this letter they're very much siding with the mayor. Because if the union calls off the strike they lose what little leverage they have to force the tough and powerful people who run this city to give them even a fraction of what they want.

Or as Frederick Douglass put it: "Power concedes nothing without a demand."

Speaking of power, I'd like to say a word or two in defense of Mayor Emanuel. I know, you don't hear me say that too often. But the truth is that this showdown has been brewing since long before he came on the scene.

Traditionally, CPS has been a top-down, vaguely militaristic system in which central-office bosses issue mandates like Zeus from above.

The teachers—you know, the folks doing the real work in the classroom—are supposed to do what they're told as new dictates come and go. It's like the weather. Don't like the latest policy on curriculum or testing mandated by the board? Just wait—they'll mandate something new in a day or two.

For better or worse—and many years it was worse—the union protected teachers from some of this nonsense. But in the last three years, Chicago mayors have started going after the union.

The assault began under Mayor Daley. Not sure why, though I'm starting to think the poor guy became a little unhinged in his last year in office after he didn't get his Olympics.

In 2010 Ron Huberman, the guy Daley put in charge of the schools, circumvented the union contract by essentially declaring an end to teacher tenure. His weapon was a personnel policy called "redefinition." So a principal could "redefine" an English teaching position into an English teaching position with a specialty in, say, basket weaving. Presto—out goes the old, "unqualified" English teacher and in comes a new one who's generally younger, paid less, and well aware of the need to worship the principal. Because children won't learn to become productive citizens without teachers who are afraid of their shadows.

Into this world marched Mayor Emanuel, like Napoleon invading Russia.

Emanuel will tell you that he knew what was wrong with Chicago's public schools and was determined to change it, because that's what strong leaders do.

My theory is that he knew next to nothing about the schools when he got elected. And what he did know was shaped by campaign rhetoric, which was itself largely based on his efforts to impress out-of-town pundits, who had themselves bought into the conventional wisdom that just about everything wrong with schools today can be blamed on bad teachers and the unions who protect them.

Whatever his motivation, Emanuel stepped up the war on the union, using the nonunion charter schools as his main weapon. In last year's mayoral campaign, he insisted that the top-scoring high schools in Chicago are charters—even though no charters are in the top ten. In fact, there's no strong evidence that charters are educating children any better than regular schools.

Once elected, Emanuel appointed charter advocates and charter funders to his schools transition team and then to the board of education. He supported efforts in the state general assembly to divert more state aid from regular unionized schools to the charters. He opened up more charters. And just in case somebody out there wasn't paying attention, he started dropping by charter schools for visits and praising them for the cameras, saying it would be wonderful if all the schools could be just like them.

Meanwhile, his only official meeting with CTU president Karen Lewis was the one last August 2 when they had their infamous squabble. He wound up telling her "Fuck you, Lewis." And she told him—well, we're not sure what she told him. But I'm sure it wasn't pretty.

Then came his obsession with the longer school day.

Yes, yes, yes—all children should spend more productive time in school. But no, no, no—we shouldn't just mandate it without giving schools the resources to do something meaningful with the time, like offer classes in art, drama, music, and dance, which are not taught in most Chicago schools.

But point this out to Mayor Emanuel and you can count on him, or one of his spokespeople, to accuse you of coddling teachers or hating on kids. He went as far as to faintly criticize Mayor Daley—though not by name—for trading a longer day for labor peace in the 2003 contract negotiations. The politicians, Emanuel said, got their "labor peace," the teachers got their "pay raises," and "our children got the shaft." As if teachers were venture capitalists sending jobs to the Cayman Islands and stashing their cash in Swiss bank accounts.

I don't think teachers will ever forgive him for that one.

The mayor also had his appointed school board rescind the raise the previous board had negotiated with the union on the grounds that the system was too broke to pay it. Even though the system wasn't too broke to raise the pay of CEO Jean-Claude Brizard—and most of his central-office appointees—over what their predecessors were making. Just as their predecessors got a boost over the people before them, and so on.

In short, after Daley took away teachers' tenure, Emanuel increased their hours, cut their pay, portrayed them as money-grubbers, closed unionized schools, and opened more nonunion charters, thus depleting the union's power through attrition. And I haven't even gotten into the merit pay issue, which he's also tried to shove down their throats.

And you wonder why teachers are so angry they went on strike.

In some quarters they garner understandably little sympathy, especially among parents who are inconvenienced or students who miss out on important athletic events or crucial college deadlines, or who just need the time in school.

Still, keep this in mind before you join the rip-the-teachers chorus. Mayor Emanuel's pushing us toward a system in which all teachers—charter and union—are lower-paid, at-will employees who have about as much job protection and say in their workplace as grill-line workers in a fast-food restaurant.

Please tell me how that's good for kids.