In an interesting exchange at the Democratic convention, Michael Moore asked Bill O'Reilly whether he would sacrifice his son to capture Fallujah. The question caught my attention because our youngest son had just returned from discussing post-college options with a Marine recruiter.

This type of question is designed to be difficult to answer -- and judging from O'Reilly's response, it was. This is because it is a rhetorical device and not a substantial question at all. This is true in four aspects.

First, it has the high standard of "sacrifice." No normal parent is prepared to sacrifice his child for any reason or objective, including military objectives. The same could be said of any desirable objective. Would you, for example, sacrifice your child to expand health care to the uninsured? Or even, in the customary example, to save the life of another of one's own children? It is hard to imagine any objective for which one would sacrifice one's child.

The question is more akin to a philosophy class exercise than a real-world moral dilemma. Service in the armed forces can be risky, but it is not tantamount to a death sentence. Were service in the armed forces a certain route to the ultimate sacrifice of one's life, the armed forces would be small indeed. Maybe that is Michael Moore's goal.

Second, the question is addressed to the wrong person. Many members of the armed forces have at least one living parent. All, however, are adult men and women in their own right. And it is they, not their parents, who choose to serve in the armed forces. The question that parents face is not whether to sacrifice their children but whether to support their children in the broad and often risky activities they must perform when they enter military service.

Third, the objective of Fallujah's pacification is too narrowly stated. Would anyone enlist for the specific purpose of keeping supply convoys moving into Baghdad? Or to open a road to a dusty town? Or to pacify a town or the occupants of a house? Or to be killed by friendly fire? Many young Americans have lost their lives in just such ways. But these are tasks incidental to the larger purpose of military service: protecting the interests of the United States.

If Saddam Hussein's tyranny is replaced by a decent government; if that new government becomes a working partner in changing the Middle East; and if this helps to prevent another major act of terrorism against the United States, are these not purposes that justify not blind "sacrifice" but at least a measure of personal risk? True, the purposes of U.S. foreign policy can surely be described far too grandly; but one can surely demean them beyond recognition as well.

Finally, the question ignores the issue of consequences. We all know that the full consequences of our decisions are impossible to predict. So are the consequences of our indecisions. If there are risks and sacrifices entailed by action, there are also risks and sacrifices entailed by inaction. Was it not precisely the burden of the Sept. 11 commission to consider why no one asked young Americans to risk their lives in a serious mission to kill Osama bin Laden before Sept. 11, 2001?

Michael Moore suggests as much when he allows that preemptive action to eliminate Adolf Hitler before World War II would have been justified. In retrospect, perhaps this case is easy enough. But would he have thought so in the 1930s? Would he not have joined the chorus of voices on both sides of the Atlantic whose refrain was that Hitler was no threat at all, and definitely not an "imminent" threat?

We live in a world of occasional hard choices. Young adults must decide whether they will serve in the armed forces. Parents must decide to accept and support those choices. And policymakers must make their best, if imperfect, judgments about when to send young men and women into harm's way. In none of these choices does Michael Moore's question offer the slightest guidance.

The writer is a senior fellow at the German Marshall Fund of the United States. He previously served as Republican staff director of the Senate Foreign Relations Committee. He will be live online today at 2 p.m. to answer questions on