[Steven M. Gillon is the resident historian of the History Channel and professor of history at the University of Oklahoma. His book, The Pact: Bill Clinton, Newt Gingrich and the Rivalry that Defined a Generation, will be published this June by Oxford University Press.]

A few years ago, while doing research for my book, The Pact: Bill Clinton, Newt Gingrich, and the Rivalry that Defined a Generation, I asked President Clinton to highlight his differences with Speaker Gingrich. "If you want to understand the differences between me and Newt you have to go back to the 60s," he told me. "If you think the 60s were generally good, chances are you are a liberal. If you think the 60s were bad, chances are you're a conservative."

That perceptive observation not only tells us a great deal about the politics of the 1990s, it provides useful insight into the issues that will shape the fall contest between Barack Obama and John McCain. While Iraq and a struggling economy may dominate the public debate, the real fight will be over the unresolved conflicts of the 1960s.

Just as the military battle between North and South in the 1860s molded American politics for the rest of that century, so the cultural civil war of the 1960s has defined politics in our time. The clashes between protesters and police in the streets of Berkeley, Chicago, and Detroit were far less violent than the bloody battles between Union and Confederate armies that took in place at Bull Run, Antietam, and Gettysburg. Both civil wars, however, produced a generation that was scarred by the memory of the struggle, deeply divided over its meaning, and determined to win a long-term fight for the hearts and minds of the American people.

The deep generational fissures forged during the 1960s never healed. They were obscured during the 1970s by stagflation, and during the 1980s by the elevated fear of Soviet expansionism. The Cold War ended, however, just as some in the 60s generation were ready to assume positions of power in the 1990s. In the 1960s they fought in the streets; now they fight in the Halls of Congress, in blogs, and in joint television appearances as "talking, or more typically, "shouting" heads.

What are they fighting about? The ideological struggle over the meaning of the 1960s boils down to a debate over what I refer to as a "culture of choice." The clashes over Vietnam, racial rioting, and student protesting have faded into memory, but they have left a lasting impression on the nation. Taken together the social movements of the decade expanded the range of individual choices people have about the way they live their lives. The civil rights movement dramatically expanded options for African-Americans. Along the way, it spearheaded other empowerment movements, especially for women and homosexuals. The range of choices expanded beyond political rights into the world of culture, where many young people questioned all forms of authority and loosened the rules of behavior that had guided their parent's generation. That cultural revolution had a ripple effect that touched nearly every institution in society.

The dramatic changes prompted a backlash among traditionalists who complained that "counterculture" values had seeped into every institution of American society, breeding permissiveness and eroding the moral glue that held society together. Neoconservative thinkers focused on the public policy consequences of a culture that valued liberation over responsibility, claiming that the abandonment of older values such as family, hard work, and discipline have produced an epidemic of divorce, poverty, and crime. At the same time, religious fundamentalists probed the moral and religious results, claiming the culture of individualism led to moral decay.

Over time the Democratic Party has embraced, with varying degrees of enthusiasm, the "culture of choice." Despite differences in style and temperament, Hillary Clinton and Barack Obama emphasize the value of diversity and individual expression and stress the positive side of the "rights revolution" in America. Not surprisingly, the groups that have benefited most from the political and legal advances of the decade -- African Americans and women -- form the electoral backbone of the Democratic coalition.

The Republican Party, on the other hand, has become home to conservatives who advocate a "culture of authority." They have turned the decade into a metaphor for a constellation of issues that resonated with millions of Americans who feared the erosion of traditional values and authority in society. For them, mention of the "60s" produces subliminal images of privileged students burning the American flag, radical feminists assaulting the family, militant minorities rioting in the streets, arrogant intellectuals mocking cherished values and blurring the distinction between right and wrong, and faceless government bureaucrats wasting hard-earned tax dollars
while people on welfare did not have to work.

The clash between these two competing views of the 1960s reached a fever pitch during the impeachment debate in the final years of the Clinton administration. "Why do you hate Clinton so much?" an interviewer asked a prominent conservative. The response: Because "he's a womanizing, Elvis-loving, non-inhaling, truth-shading, war-protesting, draft-dodging, abortion-protecting, gay-promoting, gun-hating baby boomer. That's why." Conservative journalist David Frum claimed that Clinton's personal behavior exemplified the pernicious legacy of the 1960s' sexual revolution. "[W]hat's at stake in the Lewinsky scandal," Frum wrote, "[is] the central dogma of the baby boomers: the belief that sex, so long as it's consensual, ought never to be subject to moral scrutiny."

It's possible that the two major candidates this year will be able to move the nation beyond the battle over the 1960s. In many ways, McCain was too old, and Obama too young, to participate in the youthful rebellion that shaped the decade. When President Kennedy was assassinated in November 1963, which marked the symbolic beginning of the troubles of the decade, McCain was already 27 years old. Obama was only two. In addition, polls have shown that many Americans, especially young voters, have responded to Obama's plea for moving beyond the culture wars. At the same time, McCain has been a vote but not a voice for the conservative backlash against the 60s. He also has a proven track record of being willing to reach across the aisle and build coalitions with Democrats, which is rare in the polarized atmosphere in Washington.

Despite their best intentions, however, both men will find it difficult to transcend the cultural divide forged during the 1960s. McCain will realize that the only way to win over voters disaffected with the Bush administration is to make Obama into a threatening figure, and the easiest way to accomplish that goal is to transform him into a child of the 60s. Even when not specifically mentioning the decade, both candidates will be sending subtle signals to their warring armies. Obama will stress the language of choice, praising America's cultural diversity. McCain will talk about responsibility, both at home and abroad, and the importance of traditional values. While Obama praises new rights, McCain will emphasize old rules. As much as the two major candidates will talk about the future, they will find themselves trapped in the past.