I’m ambivalent about Banned Books Week, which runs through Saturday. On the one hand, we clearly still need such a public affirmation, as the recent tumult over Sarah Palin and her “rhetorical” inquiries to the Wasilla, Alaska, public library show.

On the other, Banned Books Week offers up the sort of toothless, feel-good spectacle that makes us less likely to consider the actual ramifications of free expression.

The basic message here is one of astonishment: Why would anyone ban books when literature is such a positive and ennobling force? Yet while I agree with that, I also believe that some books truly are dangerous, and to ignore that is simply disingenuous.

Lest this make me seem an apologist for the book banners, nothing could be further from the truth. In fact, I’m against restricting anything other than material that graphically portrays certain illegal acts.

Yet it’s foolish, self-defeating even, to pretend that books are innocuous, that we don’t need to concern ourselves with what they say. If that’s the case, then it doesn’t really matter if we ban them, because we have already stripped them of their power.

Books do change things: Just think of “Common Sense,” which lighted the fuse of the American Revolution, or “Mein Kampf,” which laid out the blueprint for Hitler’s Germany.

These are very different books -- one a work of hope and human decency, the other as venal a piece of writing as I’ve ever read -- but what they have in common is a kind of historical imperative, the sense that, at the right place and time, a book can be a galvanizing factor, for good or ill.

“Mein Kampf” is a title you don’t hear a lot during Banned Books Week; the focus is more on classics such as “Song of Solomon” or “The Catcher in the Rye” that have been challenged in libraries and schools.

That’s understandable, but again, it reduces the territory of censorship and free expression to something neatly clarified, rather than the ambiguous morass it is. What happens when our ideals require us to defend a piece of writing that is reprehensible, that stands against everything we stand for?

It’s easy to condemn those who would remove “The Adventures of Huckleberry Finn” from a library, but what about “The Turner Diaries” or “The Protocols of the Elders of Zion”? Or for that matter, “Tintin in the Congo,” which Little, Brown dropped from its “Tintin” reissue series last fall after controversy arose about the book’s racist overtones?

These are not just academic questions; they are the heart of the matter, regardless of where you stand on the ideological divide. How do we defend one book without defending all? Such a notion can’t help but make us uneasy, but then, that’s one of the most essential things books can do.

We read for many reasons -- to be educated, entertained, illuminated, challenged -- but more than anything to confront someone else’s ideas. Much of the time, this is miraculous: I think of all the books that have transformed me, that literally changed the way I thought.

What would my life have been like if I had never encountered Kurt Vonnegut, or read Joan Didion’s “Slouching Towards Bethlehem,” the first book ever to make me think of nonfiction as a literary art?

Yet we forget the world is complicated, that it is full of opposing viewpoints and beliefs that, in many cases, we can’t accommodate, at our own peril. What to do, then? Sweep them under the rug? Or face them and consider what we’re up against?

This is the conversation we ought to be having during Banned Books Week, a conversation that encompasses not just a love of reading and a disdain for those who would restrict it but also the implications of the free flow of ideas. Even the most horrific things have something to teach us, something about human darkness, our capacity to go wrong.

I was thinking about this recently while reading Irvine Welsh’s new novel, “Crime,” which deals with a ring of pedophiles. It’s a squeamish, tricky read, and yet, like other writers who deal with transgressive or repugnant material, Welsh has a larger moral vision: His story is not about sex but sensibility, an investigation into the twisted landscape of the soul. There are those who’d argue that the subject he explores in “Crime” is not just provocative but detrimental, something we’d be better off without.

I couldn’t agree less; the more troublesome a piece of writing, the more we need to take it into account.

"[T]he peculiar evil of silencing the expression of an opinion,” John Stuart Mill wrote in “On Liberty” (in a quote featured on the American Library Assn. website), “is that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it. If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error.”

Here we have the point entirely, for if books don’t make us uncomfortable, they’re not doing their job.

To call that a mixed blessing is an understatement in a world where a work like “Mein Kampf” can continue to exert its awful pull. And yet to suggest otherwise is to declare that writing is unessential, which is even worse.

david.ulin@latimes.com

David L. Ulin is book editor of The Times.