The result was an even deeper schism. Kerry was arguably the worst candidate on earth to put to rest the post-1960s culture war—and his decision to embrace his Vietnam identity at the convention made things worse. Bush, for his part, was unable to do nuance. And so the campaign became a matter of symbolism—pitting those who took the terror threat “seriously” against those who didn’t. Supporters of the Iraq War became more invested in asserting the morality of their cause than in examining the effectiveness of their tactics. Opponents of the war found themselves dispirited. Some were left to hope privately for American failure; others lashed out, as distrust turned to paranoia. It was and is a toxic cycle, in which the interests of the United States are supplanted by domestic agendas born of pride and ruthlessness on the one hand and bitterness and alienation on the other.

This is the critical context for the election of 2008. It is an election that holds the potential not merely to intensify this cycle of division but to bequeath it to a new generation, one marked by a new war that need not be—that should not be—seen as another Vietnam. A Giuliani-Clinton matchup, favored by the media elite, is a classic intragenerational struggle—with two deeply divisive and ruthless personalities ready to go to the brink. Giuliani represents that Nixonian disgust with anyone asking questions about, let alone actively protesting, a war. Clinton will always be, in the minds of so many, the young woman who gave the commencement address at Wellesley, who sat in on the Nixon implosion and who once disdained baking cookies. For some, her husband will always be the draft dodger who smoked pot and wouldn’t admit it. And however hard she tries, there is nothing Hillary Clinton can do about it. She and Giuliani are conscripts in their generation’s war. To their respective sides, they are war heroes.

In normal times, such division is not fatal, and can even be healthy. It’s great copy for journalists. But we are not talking about routine rancor. And we are not talking about normal times. We are talking about a world in which Islamist terror, combined with increasingly available destructive technology, has already murdered thousands of Americans, and tens of thousands of Muslims, and could pose an existential danger to the West. The terrible failures of the Iraq occupation, the resurgence of al-Qaeda in Pakistan, the progress of Iran toward nuclear capability, and the collapse of America’s prestige and moral reputation, especially among those millions of Muslims too young to have known any American president but Bush, heighten the stakes dramatically.

Perhaps the underlying risk is best illustrated by our asking what the popular response would be to another 9/11–style attack. It is hard to imagine a reprise of the sudden unity and solidarity in the days after 9/11, or an outpouring of support from allies and neighbors. It is far easier to imagine an even more bitter fight over who was responsible (apart from the perpetrators) and a profound suspicion of a government forced to impose more restrictions on travel, communications, and civil liberties. The current president would be unable to command the trust, let alone the support, of half the country in such a time. He could even be blamed for provoking any attack that came.