Nicholas Kristof has written an excellent op-ed in the NYTimes today that I am in total agreement with.

So is President Bush a liar?

Plenty of Americans think so. Bookshops are filled with titles about Mr. Bush like "Lies and the Lying Liars Who Tell Them," "Big Lies," "Thieves in High Places" and "The Lies of George W. Bush."

A consensus is emerging on the left that Mr. Bush is fundamentally dishonest, perhaps even evil — a nut, yes, but mostly a liar and a schemer. That view is at the heart of Michael Moore's scathing new documentary, "Farenheit 9/11."

In the 1990's, nothing made conservatives look more petty and simple-minded than their demonization of Bill and Hillary Clinton, who were even accused of spending their spare time killing Vince Foster and others. Mr. Clinton, in other words, left the right wing addled. Now Mr. Bush is doing the same to the left. For example, Mr. Moore hints that the real reason Mr. Bush invaded Afghanistan was to give his cronies a chance to profit by building an oil pipeline there.

"I'm just raising what I think is a legitimate question," Mr. Moore told me, a touch defensively, adding, "I'm just posing a question."

Right. And right-wing nuts were "just posing a question" about whether Mr. Clinton was a serial killer.

I'm against the "liar" label for two reasons. First, it further polarizes the political cesspool, and this polarization is making America increasingly difficult to govern. Second, insults and rage impede understanding.

Lefties have been asking me whether Mr. Bush has already captured Osama bin Laden, and whether Mr. Bush will plant W.M.D. in Iraq. Those are the questions of a conspiracy theorist, for even if officials wanted to pull such stunts, they would be daunted by the fear of leaks.

Bob Woodward's latest book underscores that Mr. Bush actually believed that Saddam did have W.M.D. After one briefing, Mr. Bush turned to George Tenet and protested, "I've been told all this intelligence about having W.M.D., and this is the best we've got?" The same book also reports that Mr. Bush told Mr. Tenet several times, "Make sure no one stretches to make our case."

In fact, of course, Mr. Bush did stretch the truth. The run-up to Iraq was all about exaggerations, but not flat-out lies. Indeed, there's some evidence that Mr. Bush carefully avoids the most blatant lies — witness his meticulous descriptions of the periods in which he did not use illegal drugs.

True, Mr. Bush boasted that he doesn't normally read newspaper articles, when his wife said he does. And Mr. Bush wrongly claimed that he was watching on television on the morning of 9/11 as the first airplane hit the World Trade Center. But considering the odd things the president often says ("I know how hard it is for you to put food on your family"), Mr. Bush always has available a prima facie defense of confusion.

Mr. Bush's central problem is not that he was lying about Iraq, but that he was overzealous and self-deluded. He surrounded himself with like-minded ideologues, and they all told one another that Saddam was a mortal threat to us. They deceived themselves along with the public — a more common problem in government than flat-out lying.

Some Democrats, like Mr. Clinton and Senator Joseph Lieberman, have pushed back against the impulse to demonize Mr. Bush. I salute them, for there are so many legitimate criticisms we can (and should) make about this president that we don't need to get into kindergarten epithets.

But the rush to sling mud is gaining momentum, and "Farenheit 9/11" marks the polarization of yet another form of media. One medium after another has found it profitable to turn from information to entertainment, from nuance to table-thumping.

Talk radio pioneered this strategy, then cable television. Political books have lately become as subtle as professional wrestling, and the Internet is adding to the polarization. Now, with the economic success of "Farenheit 9/11," look for more documentaries that shriek rather than explain.

It wasn't surprising when the right foamed at the mouth during the Clinton years, for conservatives have always been quick to detect evil empires. But liberals love subtlety and describe the world in a palette of grays — yet many have now dropped all nuance about this president.

Mr. Bush got us into a mess by overdosing on moral clarity and self-righteousness, and embracing conspiracy theories of like-minded zealots. How sad that many liberals now seem intent on making the same mistakes.