Without much notice and even less discussion, "civil war" has become the new abracadabra phrase for American foreign policy.

Sen. Joe Biden leads the magicians who've seemed to convince everybody that it never makes sense to get involved in a civil war. In March, he screamed from the Senate floor: "I'm so tired of hearing on this floor about courage. Have the courage to tell the administration, ŒStop this ridiculous policy you have.' We're taking sides in a civil war."

Biden's not alone. It's become a standard talking point for most major opponents of the Iraq war. The Democrats' Iraq-withdrawal point man in the House, John Murtha, says we're "caught in a civil war" in almost every interview, as if this is the geopolitical equivalent of "I've fallen and can't get up." Senator Majority Leader Harry Reid said last week that, "We stand united ... in our belief that troops are enmeshed in an intractable civil war."

The assumption behind this gambit is obvious: Declaring it a civil war is like blowing a whistle at the end of the game. There's nothing left to do but pack up the equipment and go home.

Al-Qaida in Iraq (and perhaps the Iranians) have clearly figured this out. That's why they consistently try to stoke sectarian passions by, for example, bombing the Golden Mosque in Samarra, Iraq's holiest Shia shrine. That 2006 attack prompted the formation of Shiite militias and death squads, which in turn provided fresh evidence that Iraq was heading toward civil war.

Meanwhile, the Bush administration has been desperate to keep the press from describing the situation in Iraq as a "civil war," for the obvious reason that the administration will lose its remaining support if the American public thinks this is just a civil war.

OK, but here's what I don't get: Why? Why is it obvious that intervening in a civil war is not only wrong but so self-evidently wrong that merely calling the Iraqi conflict a civil war closes off discussion?

Surely it can't be a moral argument. Every liberal foreign policy do-gooder in Christendom wants America to interject itself in the Sudanese civil war unfolding so horrifically in Darfur. The high-water mark in post-Vietnam liberal foreign policy was Bill Clinton's intervention in the Yugoslavian civil war. If we can violate the prime directive of no civil wars for Darfur and Kosovo, why not for Kirkuk and Basra?

If your answer is that those calls for intervention were "humanitarian," that just confuses me more. Advocates of a pullout mostly concede that Iraq will become a genocidal, humanitarian disaster if we leave. Is the prospect of Iraqi genocide more tolerable for some reason?

Then there are those who take the fatalist's cop-out: Civil wars have no good guys and bad guys. They're just dogfights, and we should stay out of them and see who comes out on top. But that's also confusing, because not only is it not true, but liberals have been saying the opposite for generations. They cheered for the Reds against the Whites in the Russian civil war, for the Communists against the Fascists in the Spanish civil war, and for the victims of ethnic cleansing in Yugoslavia and Sudan. Surely liberals believe there was a good side and a bad side in the American Civil War?

Ah, but I'm missing the point, they might say. It's not that there aren't good guys and bad guys, it's that we can't do anything about it and therefore it's not in our interests to try. Then they point to, say, the civil wars in Lebanon or, closer to their hearts, Vietnam.

Let's stipulate Vietnam was a civil war. So what? There were certainly good guys and bad guys, and let the record show the bad guys won, which was not in our interests. This in turn led to many humanitarian calamities. And, recall, another superpower intervened in that civil war, and it worked out pretty well for the Soviets.

More to the point, it's ludicrous to believe America has no interest in who wins or loses various civil wars, including Iraq's. The 20th century would have been a lot more pleasant if the Bolsheviks had lost the Russian civil war, and the 21st will be a lot more ugly if Sunni Salafists or Iranian pawns win in Iraq.

I'm not saying a civil war is a desirable environment for anybody. But nor is it a geopolitical black box absolving all concerned from moral and strategic discrimination. And yet that is exactly what advocates for withdrawal from Iraq want everyone to believe, but only when it comes to Iraq.