Al Gore had so wanted to nab the Capitol. He had planned all along on making Washington, DC a key link in the Live Earth concert chain, starting hours after Sydney, right after London, right before New York. Around the world, 2 billion viewers - including many of those mythical millions who, Billy Crystal or Whoopi Goldberg inform us, dutifully watch every year's Oscars - would watch carbon-conscious rock stars shatter their amps in view of the massive Capitol dome.

And then Oklahoma Sen. James Inhofe, a global warming skeptic, put the brakes on it. Organizers were shocked: not even an Oscar and a clutch of Huffington Post essays could override the power of a duly-elected pain-in-the-ass. The concert was scrapped until Friday, when the Smithsonian offered up the grounds of the Museum of the American Indian. The word went out online, Garth Brooks and Trisha Yearwood booked their plane tickets, and on Saturday the Mall's newest taxpayer-funded field trip destination hosted a pathetically small crowd in front of, well, basically, nothing. Look ahead and you could see the stage. Crane your neck and you could spot some grass and footpaths and some perplexed tourists. Gore, looking far less imposing than the holographic Gore that beamed into in Tokyo, put his sunniest spin on the new location. "It wasn't the cavalry that came to our rescue," he said. "It was the American Indians."

Sure, fine, but everybody knows the truth: Gore really needed that Capitol in the background. He needed a display of power and there is no greater display of power than shaking your fist in front of a giant crowd as the vast legislative house of the world's superpower looms behind you. American troops are in Iraq because of a decision made inside that building. A wall along the U.S.-Mexico border that would immediately become the longest and largest in history has been funded, and may be built, because of a decision made inside of there. A rally in the view of that dome has the imprimatur of the American empire. That's what you want those 2 billion people to see.

Just don't count Cullen Murphy, the longtime Atlantic managing editor, among the billions. In Are We Rome? The Fall of an Empire and the Fate of America he envisions a happy day when Al Gore and Jim Inhofe won't be brawling over concert licenses. "I doubt I'm the only person," he writes, "who has trod, with lofty step, the sculpted gardens of the Capitol and been seized with a vision of how the city might appear as a ruin."

Murphy hardly writes about anything without treading through it. When he was a boy he toured Rome "walk[ing] alone in the early morning with a sketchbook." He's visited every important outpost of the Roman Empire and some of the key sites of Pax Americana, like Bagram Air Base. As an editor he published some of the glummest predictive journalism ever written, some of it (like James Fallows' The Fifty-first State?) depressingly prescient. His brief book has the feel of a life's work, much like Gore's post-politics output. Both men plunder the past to predict the future, Gore with his ancient glacier data and wind patterns, Murphy with the Rome collection at the Boston Aethenaeum.

And Murphy has the easier case to prove. Is America the new Roman Empire? Yes, obviously it is. America dominates the planet militarily, economically, culturally, as much or more than Rome ever did. Americas know their position and their superiority as surely as the Romans did. The Capitol, like every other ruin-to-be in Washington, was modeled in the Roman image, and half of it is named for the Roman Senate. Our confidence leads us to make the same kinds of military blunders as the Romans, and the only argument is whether Iraq is our Teutoburg Forest or our Adrianople - if we've learned our lesson and will stop pushing outside our boundaries, or if we've used up all of our get-out-of-jail cards and are primed for a fall.

Americans started comparing ourselves to the Romans long before we had an empire to worry about - shortly before we were Americans at all. Before the Revolution, as Murphy points out, Americans performed Joseph Addison's Cato: A Tragedy in Five Acts and walked to the wrap parties ready to trade life for liberty. When George Washington declined absolute power and when he walked away from the presidency after two terms, Americans reached back to a Roman hero to pay their tribute: Washington was Cincinattus. The statue of a toga-clad Washington handing back his sword to the masses now sits in the Smithsonian, although Murphy worries that the "reference is probably lost on most visitors: Washington looks like a man in a sauna reaching for a towel."

Our cognizance of Rome and of her downfall is an insurance policy. A culture that tells and re-tells the Roman epic everywhere from the founding to HBO series to the second Star Wars trilogy has obviously paid its attention to history. Not enough, says Murphy: We don't realize that an empire that's going to last has to start acting with an eye on the future. So we need a "hundred-year workout plan" to correct our short-sightedness, and we need to stop privatizing government services. "Yes, it takes some imagination to see how corrosive privatized government will prove to be many decades down the road," Murphy argues. "Start thinking in centuries."

Does that sound like a stretch? Well, it is. The rest of Murphy's problems that threaten to turn the Capitol into a new Coliseum are problems of centralization, power, overconfidence; we can protect our culture with a border wall, we can remake Mesopotamia if we clap a little louder. Privatization leaps almost out of nowhere, out of Murphy's anger at political corruption and out of documents that reveal powerful Romans trading favors for cash. So he argues points like "as in Rome, privatization still includes turning over government departments to incompetent cronies, empowering private individuals at the expense of public intentions." His example? Michael Brown at FEMA.

Mull that one over. If you're looking for an example of the ills of privatization, of shrinking government, does anyone disprove your point like Michael Brown? He was the man at the top of an organization of Laurel-and-Hardy-level screw-ups, which had been folded into the Department of Homeland Security, a font of even greater screw-ups. His pivotal moment, his own Teutoburg Forest, was the evacuation and clean-up of New Orleans before and after Hurricane Katrina. While Brown was blowing it, what organization was shoveling supplies to survivors with epic efficiency? That's right: Wal-Mart.

But that's merely more fuel for Murphy's nightmare. He sees three bleak possible future for Pax Americana. In one, the borders are locked off and the security state peeks into every bedroom. In another, America's megalopolises break off into city-states: Cosimo di Medici, meet Michael Bloomberg. In his grimmest scenario the breakdown of controlling authority and the sense of "in-this-togetherness" that government provides leads to "the rise of corporate feudalism on a global scale."

Sounds bleak, but is that a scenario where the American empire falls and snooty Chinese tourists snap photos standing aside the rubble of old Washington? No; it's a scenario where America has basically won. Commerce has won out. Culture has won out. If you believe that spreading American cultural norms around the world is more important than planting the flag or christening some new military camp, what's there to fear from a future where government controls less and less and business governs the affairs of man more than nationalism?

Again, that's Murphy's worst nightmare. His other predictions of doom are cut down by his optimism about America's ability to adapt, to absorb immigrants, to trade, to tolerate. "America's powerfully absorptive and transformative domestic culture" is "more than a match for any challenge and doesn't need to be ‘run' by bureaucrats or told what to do." This isn't a prediction that American hegemony will go on and on and on like some propaganda poem commissioned by Augustus. It won't, obviously. But it would be folly to try and preserve American power (or American culture) by locking down the demographics and the bureaucracy that we have today and refusing to experiment for fear of wrecking everything. Not only does that flout the very reason Pax America has been so successful, it indulges the habit that so irritates Inhofe about Al Gore: working from pessimism and drawing a straight black line from the present into the infinite, ominous future.

David Weigel is an associate editor of reason.

Discuss this article online.