For many, the tragic events in Paris have highlighted the importance of free expression. But beyond such shocking terrorist acts, of course, free expression is always under threat, as evidenced by the American Library Association’s tracking of book challenges and its annual Frequently Challenged Books list. But what do we really know about book banning in America?

In Book Banning in 21st-Century America (Rowman & Littlefield), author Emily Knox, assistant professor of library and information science at the University of Illinois at Urbana-Champaign, goes beyond the usual legal discussions of free speech and censorship, looking at why people challenge books—and what those challengers tell us about the immense power of reading. I recently caught up with Knox to talk about book banning in America.

ARA: The murders in Paris over cartoons depicting the Prophet Muhammad shocked the world and rallied many to the cause of free expression. But threats to free expression are, in fact, frequent, though most are far less dramatic. Can you talk about what book banning typically looks like in America?

Emily Knox: It’s usually much more personal. A kid will bring home a book, often as part of either a curriculum or because one of the kids has gotten it from the library, and the parents will take a look at the book, and they’ll be upset about something they find in it. What I find in my work is that issues of sexuality come up most. The book that came up most in my cases is Sherman Alexie’s The Absolutely True Diary of a Part-Time Indian. That book has been banned in many places across the country, and it’s really for two or three sections that deal with teenage boys’ sexuality. But other things also come up. For me, my most interesting case is one that happened out in Seattle, where a woman was very upset about Brave New World, because, in that book, Native Americans are called savages, and her daughter came home crying because she’s a Native American and her teacher told her that this is a classic book by a great writer.

For the last two years, Captain Underpants has been at the top of the ALA’s most-banned list. What is it about Captain Underpants that people are so afraid of?

Well, that’s really an issue of behavior. There are a few things going on in Captain Underpants. One common concern is about the behavior of the kids who read it—that little boys will read it and then they start doing diaper jokes, fart jokes, that sort of thing. Also, some of the concerns revolve around the fact that there are improper spellings in the books—for example, when the boys write their own comic books, that they don’t spell well. And there are concerns that children are reading below grade, that the book encourages their kids not to push themselves to read books without pictures in them, not to read chapter books. So there’s actually a lot going in the Captain Underpants. And in some ways it ties to all these stereotypes about boys, and how they act and what sort of things they want to read, and how Captain Underpants reinforces some of those perceptions.

In a case in the headlines now, parents in Highland Park, a wealthy suburb of Dallas, have objected to students reading David K. Shipler’s The Working Poor: Invisible in America. Is this kind of politically driven challenge common?

A: There was another similar shake-up a few years ago, when Barbara Ehrenreich’s book Nickel and Dimed was banned for about the same reason. In the book, I talk a little bit about how a lot of book banning really goes back to the culture wars, that this is really a clash of worldviews more than anything else. What I show in my book is that challenges are often about people wanting their schools and libraries to reflect their own values. And if you think that people should pull themselves up by their bootstraps, but your school is teaching a book that says something else, that’s going to be a problem for you.

But what I’m really trying to get at in my book is how people understand the act of reading. Why does it matter that things that you might disagree with come up in books? I try not to come from a left/right point of view but from the central idea that reading is a powerful practice, and that all of us believe that reading changes lives. And we can see how much reading changes lives, by looking at what books people want to ban, and why they want to ban them. What I find is that what people who want to ban books all have in common, whether they’re from the left or the right, is that they believe in one type of interpretation—in the book, I call it a monosemic interpretation: in other words, there is no sense that people could read the same text and come away with different things, there’s only one way of looking at how texts work. That’s a common thread I’ve found among all people who challenge books—there’s just not much thought that different people can look at a book in different ways.

A lot of people, myself included, have a visceral reaction to the idea of banning books. Was there anything that surprised you when you were putting this book together? In doing your research, did you begin to see things with a little more nuance?

Yes, I really was surprised at how sympathetic I felt toward a lot of the challengers. I interviewed many of them, and, you know, these are people who are very concerned about their kids and their communities. And they’re willing to put themselves on the line and receive horrible messages so they can say, “Well, I think this is right.” It was surprising to me that I felt a lot of empathy toward some of these challengers. Often these issues really cut through communities. It leads to people not talking to their neighbors anymore. There’s often not much healing that takes place. And there are occasionally these blowups with huge media-driven hearings. I would go to hearings, and you could just see anger from people on both sides. And it really can hurt people’s lives and divide neighbors from each other.

To me, book challenges almost always seem outrageous. But in your research, did you find that some challenges were thoughtful? Was there benefit to at least having a discussion about a book, even if it is in the context of someone trying to ban it?

I think they are often very thoughtful. And I don’t necessarily think that it’s wrong for people to challenge books. As a professional who takes the kind of ethics of the American Library Association seriously, it is never my job to censor a book, of course. But I am willing to talk to people and really try to find a book that they would prefer to read. That’s my job. And when I teach my classes, teaching people who are going to be librarians or information professionals, what I try to show them is that it’s our job to protect all knowledge, even knowledge that we ourselves disagree with. But that doesn’t mean that we can’t have a conversation about what people find problematic.