So is it the same person or not? Several weeks have passed since newspapers ran side-by-side pictures of the new president of Iran and an unidentified student revolutionary with his paws on a blindfolded American during the 444-day occupation and hostage-taking at our embassy in Tehran 25 years ago. The Iranian government insists it's someone else in the embassy photo, but the United States is withholding judgment.

We all know the answer, though, don't we? Of course it's not the same person. How many of us are the same person in our late forties that we were in our early twenties -- even if that older person occupies the same body (or, more likely, a somewhat decayed version of the same body)? Mahmoud Ahmadinejad seems to have changed less than most. He retains his rosy-cheeked idealism. "We did not have a revolution in order to have democracy," he declared in May before winning the presidential election.

There is a lot of talk about long memories in dealings among nations. But it is short memories that make the wheels of international relations turn. At the State Department, they must be hoping desperately that Iran's president is not the man in the earlier photograph, because that will make the embassy episode hard to ignore.

Just look what's going on next door in Iraq. It's like a race to see who can forget the most the soonest. The United States marched into Baghdad two years ago terribly excited to start a process known as "de-Baathification," which sounds like a 10-year-old boy's fantasy but which meant purging representatives of Saddam Hussein's Baath Party from the government and other seats of power. But as the country sank into chaos, the occupiers came to realize that it's hard to run a country without all the people who ran it last week. So forget about that. Baathists, except for those at the very top, are welcome to resume where they left off.

In fact, the judge who is hearing the first mass murder charges against Hussein is a former Baath Party member named Raid Juhi. Apparently, he is good at the job. The Americans in charge are pleased and eager to keep him. I bet he was good at the job when he was judging for Hussein, too. The truth is that the type of person who did well in Hussein's Iraq is not unlike the type who does well in post-Hussein Iraq -- or in Germany 1938 or Germany 1948. Or in America 2005, for that matter. (As Tom Lehrer once sang about a Nazi scientist hired by NASA: " 'Once the rockets are up, who cares where they come down? That's not my department,' says Wernher von Braun.") Unfortunately, in our initial enthusiasm for de-Baathification, we said no Baathists could work for the tribunal we set up to prosecute high officials of the former Baath government. I guess it seemed reasonable at the time. Now we're sorry. But Iraq's deputy prime minister and chief de-Baathifier is insisting that our rule must be enforced and Juhi must go.

And who is this anti-American troublemaker? It's Ahmed Chalabi. Chalabi spent decades in exile, meddling a bit from afar but devoting most of his energies to financial chicanery. For a few months in 2003 we forgot Chalabi's little foibles and promoted him as the Nelson Mandela of Iraq. Why? Because the Bush administration liked what he was saying about how the weapons of mass destruction covered the streets of Baghdad like manna from heaven. That turned into an embarrassment, and it's been "Ahmed Who?" ever since.

Chalabi is a secular, westernized type. But in the recent presidential election, he forgot all that and made a Faustian alliance with the popular religious extremist, Moqtada Sadr. In 2003, Juhi tried to have Sadr arrested for ordering the assassination of a clerical rival. Nothing came of that, but Chalabi still has it in for Juhi. At least for the moment.

The charges against Hussein that Juhi is hearing concern the slaughter of 150 men and boys in a town called Dujail. This is supposed to be a warm-up for the prosecution of Hussein and others for the notorious Anfal campaign against the Kurds in northern Iraq in the late 1980s, where poison gas was used and the usual number given for deaths is 150,000.

I say "notorious" because Anfal -- and especially the use of poison gas against civilians in a town called Halabja in 1988 -- became crucial parts of the Bush administration's defense of the war after the initial justifications (such as all those weapons of mass destruction) collapsed. But the notoriety is recent.

Two decades ago, we knew all about these events, yet we did nothing and said almost nothing. In 1983, as Iraq was starting to use mustard gas against Iranian soldiers, Donald Rumsfeld went to Baghdad for President Ronald Reagan and apparently made one veiled reference to this amidst a lot of suck-uppery sending the larger message that we were tilting in Iraq's favor in the Iran-Iraq war. After Halabja, the State Department worked actively to convince the world that Saddam Hussein was not responsible.

The theory seems to be that, contrary to Santayana, forgetting the past can be a way to avoid repeating it. Hasn't worked so far.

The writer is editorial and opinion editor of the Los Angeles Times.