Here’s the question: If a teacher shows students lewd and lascivious material, can she escape punishment because that material is part of an approved curriculum? Not if a new bill in Kansas is approved. The case raises some difficult questions: Are some forms of knowledge harmful? If so, who gets to decide which ones? …and how?

Those aren’t the only difficult questions. The bill itself is hard to figure out at first glance. Politico reported yesterday that the bill has already passed through the Senate and is heading for the House. Senate Bill 56 amends an earlier law. If 56 passes, teachers will no longer be able to defend themselves against charges of impropriety by saying that any offensive material was part of an approved curriculum.

It’s a little confusing, so I’ll say it again: An earlier state law had specified that librarians, college professors, and K-12 teachers could be prosecuted for using any material “harmful to minors” unless that material was owned (or leased) by the school or library and used as part of an “approved course or program of instruction.”

Under the proposed law, professors and librarians could still claim that defense, but K-12 teachers could not. The bill had its origins in a poster controversy last year. The poster listed ways people might act on their sexual feelings. The sponsor of today’s bill, Senator Mary Pilcher-Cook, called it “highly offensive and harmful.”

Is this a misdemeanor?

Pilcher-Cook’s attitude raises a central culture-war question. The notion that children in school must be protected from harmful words and ideas is a vital tradition among educational conservatives.

To be clear, not only conservatives want to ban harmful ideas from schools. Progressives, too, often assume that certain kinds of knowledge are harmful. From Huckleberry Finn to the University of Oklahoma, for instance, racist language and ideas have long been targets for progressive censorship. Merely hearing racist words, some activists have argued, can damage children.

In the case of sex education, though, progressives tend to think that more information is a good thing. Students need to hear explicit sexual terms. Students need to know about specific sex acts. Learning it in a classroom setting, the classic progressive argument goes, is better than learning it on the street.

Conservatives, in contrast, often think that exposure to sexual information is damaging. In this case, as Senator Pilcher-Cook told Politico, the “damage” caused by the middle-school sex-ed poster “could not be undone.” Merely hearing these words constitutes harm to children.

As I argue in my new book, conservatives have traditionally enjoyed great political success with these anti-sex-ed arguments. In the 1970s, for example, conservative school board member Alice Moore from Kanawha County, West Virginia, rallied protesters against a new series of textbooks by reading part of a salacious passage, then refusing to go on because the material was too offensive.

Children, the argument goes, are harmed by seeing or hearing certain sexual terms. They are harmed by knowing about certain sex acts. One goal of proper education, some feel, must be to protect children from these kinds of sexual knowledge.

The language of the Kansas bill makes clear the crux of the issue. If enacted into law, teachers could be prosecuted for sharing material that is “harmful to minors,” even if that material is part of an approved curriculum. Of course, such a law would put teachers in a terrible pickle.

Supporters of the bill insist that common-sense guidelines would protect teachers. As we all know, though, common sense is anything but common. Teachers and parents who think explicit sexual information is helpful would be up against those who think the exact same information is harmful.

Beyond such concerns, though, the language of the bill reveals our divided conscience. No one thinks teachers should harm students. But is exposure to information about sexual behavior—even explicit information—harmful?