Today's observance has its origins in the laudable impulse to memorialize those who died in the nation's wars. Because that impulse is tied to grief, however, the remembering is narrow. Its object is ``honor" and so the past is glorified, as the graves of the fallen are decorated on Decoration Day. Because it is natural to regard those who died in war as heroes, it can seem necessary to affirm the wars themselves as heroic, too. The decoration extends to martial rhetoric. This is a human response, dating at least to Homer, but such remembering results, ironically, in a kind of amnesia. The true condition of war -- what continually leaves battle-scarred survivors opposed to war -- is readily forgotten.

In the 20th century, two occurrences initiated a broad change in consciousness. Industrialized war so devastated the populations of the battle zones that they found it impossible to resume the ancient habit of glorification. The past would be remembered differently.

Germany and Japan, in particular, emerged as pacifist nations -- an extraordinary turn. But, secondly, when nuclear weapons entered the story, the future was transformed, too. Traditional notions of proportionality and civilian immunity were obliterated. For the first time, large numbers of humans began to insist that a world without war was not only possible but mandatory. The most respectful way to memorialize the war dead was to deny that they had to be succeeded.

But during the Cold War this discussion became framed as debate between tough-minded ``realists" and soft-headed idealists. Across a generation, the realists seemed to have the better of the argument, but when that era of jeopardy ended non violently, it was the idealists (the democracy movements in the East, the peace movements in the West) who turned out to have perceived what was truly real. The national security establishments on both sides of the Iron Curtain, presiding jointly over the manufacture of more than 100,000 nukes -- to cite only their most egregious mistake -- had fatally undermined the very notion of security. That the world survived that mad competition had nothing to do with what realists perceived or proposed.

Lately, in Washington, they have been at it again, insisting that new threats (if not communists, terrorists; if not dominoes, oil) justify going to war. But once more, the true face of war has efficiently shown itself. The true meaning of national security is apparent, too. Confronted with challenges from malevolent antagonists, the realists had wildly exaggerated what such enemies were capable of. Saddam Hussein and Osama bin Laden posed real dangers, but not remotely what realists warned of, and not what they then went after. The realists, that is, missed what was real. With their war in Iraq, in the context of their global war on terrorism, they created new conditions of national insecurity that surpass any damage of which Saddam or bin Laden were capable. An Arab world enflamed against America. Muslims seeing in us a mortal enemy. The Israeli-Palestinian conflict escalated. Other nations (not only Iran and North Korea, but perhaps Russia and China) girding for battle against us. On the ground in Iraq, the full meaning of such consequences is blood red -- Iraqi blood, American blood. As always, the first penalty for the failures of such realism is paid by the dead.

This Memorial Day, especially, we yearn to honor the more than 2,700 US soldiers who have died in Iraq and Afghanistan. What is the proper way to remember them? Even in condemning what made it necessary, can we not acknowledge the selflessness of their sacrifice? At Troy, soldiers were roused to battle by the promise that their exploits would be sung of far into the future. Is it a betrayal of our soldiers that we no longer want to sing? Does it mean they died ``in vain" if we insist that no one else should die?

Perhaps on Memorial Day we can also remember alternative hopes. Not soft-headedness, but tough-minded measures required to build a different world.

What if we invested as much in preventing war as in the fighting of it? (What, say, would the Middle East be if the billions spent in Iraq had funded instead a new Palestinian economy?)

Changes in the way we memorialize the past make possible changes in the way we envision the future. But here, too, it is the sacrifice of soldiers that makes possible such change. Indeed, it begins with them. The fallen heroes remind us with their lives that war must stop.

James Carroll's column appears regularly in the Globe.  

©2006 Boston Globe