Imagine that genocide were taking place -- thousands of children dying, women raped, men mowed down in groups -- just as the American political parties held their quadrennial conventions. Surely it would be a major subject of conversation and alarm as the nation's political elite debated their agendas for the coming four years.

No? No. Of course not. We all know that genocide is taking place, in the Darfur region of western Sudan, and you did not hear it discussed during eight nights of rousing oratory at two conventions.

Well, but be fair, you say; party conventions are hardly the place or time to talk about such depressing matters. Behind the scenes, the foreign policy mandarins of each party, the masters of "never again" rhetoric, must have been consumed by the issue. Right?

No again. In Boston and New York, the Council on Foreign Relations, the nonprofit membership organization of the foreign policy elite, held panel discussions on the central issues of the next four years. Ambassadors and Cabinet ministers mingled with professors and pundits. They congratulated each other on how foreign policy has moved, after many years on the periphery, to the heart of this presidential campaign. They discussed Iraq, terrorism, trade deficits, China, Korea, the Voice of America, European public opinion, port security . . . but not Darfur. A million people may die, tens of thousands already have, and -- nothing.

How can this be? One explanation would be that Americans (and Europeans, who were decently represented in the audiences of both panel discussions) just don't care all that much. The victims of Darfur are poor, black and far away. The issues are hard to understand. U.S. and European security is not at stake.

This was more or less George W. Bush's attitude when he was running for president in 2000 and said the Clinton administration had been right not to intervene to stop the 1994 Rwanda genocide, in which some 800,000 people died. "That's an important continent," he said of Africa, "but there's got to be priorities. . . . We can't be all things to all people in the world."

A more charitable explanation would be that people care but that stopping genocide is not easy. Villages are being destroyed across an area the size of Texas. Sudan's air force and its proxy gangster militia can induce starvation simply by poisoning wells or covering them with sand. Sudan's government opposes and frustrates outside intervention. U.N. Security Council members such as China oppose anything that affronts Sudan's sovereignty.

But Darfur should be debated precisely because it raises difficult questions -- and because those questions aren't so different from the challenges that were posed by Iraq and Kosovo and that may arise again in Iran, or Burma, or Zimbabwe, or in many other spots. When is it legitimate to infringe on a nation's sovereignty to ensure global security or rescue an imperiled population? Who should perform those jobs? What if the United Nations says no?

France and Germany opposed President Bush's war in Iraq in part because the international community was not unified. Now U.N. Secretary General Kofi Annan is clear: An international rescue force is required. But still they hesitate. Why?

Sen. John F. Kerry criticized Bush for failing to conduct adequate diplomacy before waging war on Iraq. But on Friday, in an admirably tough statement on Darfur, he urged Bush to "insist on the triumph of our common humanity over least common denominator diplomatic compromises." So what are the rules? If the Security Council says no, will a rescue mission -- in violation of international law -- still be the right thing to do?

"Being a witness to genocide is not an option," Bush's ambassador at large for war-crimes issues, Pierre-Richard Prosper, said in April, on the 10th anniversary of the Rwanda genocide. "Saving lives is a moral obligation of all nations and all individuals . . . we should always choose to act rather than hope that with time reason will prevail."

Did he mean it? The Bush administration seems to have learned at least one lesson from Rwanda: Do not let history record that you were indifferent as a genocide unfolded. Secretary of State Colin Powell has visited Darfur; the White House has pressed the Security Council for action. Republicans may have been mostly silent in New York, but if you scour the party platform you will find a condemnation of Sudan's government. The administration has sent a great deal of food. On the 10th anniversary of the Darfur genocide, no one will be able to say that Bush and his people took no notice.

But if there is such an anniversary -- if the genocide proceeds deliberately before us, even as we have all been warned and warned again -- what will it say about the Bush presidency? Well, he was very busy in the summer and fall of 2004, and Darfur is far away.