“We think ‘We’re all in this together’ is a better philosophy than ‘You’re on your own.’” Not surprisingly, former President Bill Clinton best summarized the choice that Americans face this fall. Now that the theatrics of both conventions are behind us, the stark differences between the parties are clear—but so, too, are the limits of the election debate.

On economic policy, Mitt Romney and Paul Ryan have responded to the worst crisis since the Great Depression by peddling the same nostrums Republicans have preached for decades, in good times and in bad: more tax cuts, primarily for the wealthy; continued deregulation for the banksters who almost destroyed the economy; even more shredding of an already tattered social safety net, with the burdens falling most heavily on the weakest and poorest; and a determined assault on Medicare, Medicaid and Social Security, with privatization as the party’s eventual goal.

On foreign policy, the neocons surrounding Romney terrify GOP pragmatists like Brent Scowcroft (and, as Rick Perlstein and JoAnn Wypijewski point out in this issue, they also alienate key sectors of the party’s base). And Romney makes a mockery of his budget-balancing claims by promising to further bloat an already grotesquely swollen Pentagon.

Nowhere is the polarization of the parties clearer than on social issues. The Democrats in Charlotte were unabashed cultural warriors, making abortion rights, marriage equality and immigration reform—including a warm embrace of the DREAM kids—a central part of their convention’s theme. This was in strong contrast to the GOP, whose right wing turned the party platform into a bludgeon with which to attack the rights of women, gays and immigrants.

To repair the economy, President Obama pledges to build from the middle class out, though without offering much detail on what that means other than resisting Republican extremism—blocking proposed deep cuts in education, opposing efforts to roll back financial regulation and healthcare reform, and promising not to savage Social Security, Medicare and Medicaid.

On foreign policy, the Democrats confidently combined muscle flexing—“Osama bin Laden is dead”—with an appeal to Americans tired of endless war. The president sought credit for ending the war in Iraq and for drawing the one in Afghanistan to a close, promising that the money saved could be used for nation-building here at home.

What’s notable about the election debate leading into November, however, is how much it excludes. This election features the most polarized ideological choice since Reagan versus Carter in 1980. Yet the issues that are fundamental to our nation’s future have been excluded from that debate.

Climate change—whose devastating effects are growing more evident with each passing month—received a cursory acknowledgment from Obama, while Romney pandered tastelessly to the GOP’s know-nothing denialism. But as Mark Hertsgaard highlights on page 6, Obama’s approach is better only by comparison; neither party offers a sensible policy on a danger that is becoming increasingly difficult to ignore.

The United States can no longer afford to police the world. And Obama’s eager embrace of extreme presidential powers—even the “right” to target and kill American citizens without a warrant, much less a trial—threatens fundamental rights. Yet neither has been mentioned in this campaign. Nor does either candidate offer a plan to bring military spending down to sensible levels.

Extreme inequality now imperils not just our economy but our democracy itself. Romney, the unabashed champion of the 1 percent, welcomes the flood of corporate money in politics. Obama sensibly argues that billionaires shouldn’t pay lower tax rates than their secretaries, and he’s nodded cautiously in the direction of campaign finance reform. But while he has called for a revocation of top-end tax cuts, and the Democratic platform has good language on labor rights and raising the minimum wage, Obama has not been a forceful advocate for policies that would share more widely—and more wisely—the rewards of growth.

The 2012 election is turning into a very fierce and negative campaign between two candidates representing very different directions (and vastly different Americas). Yet both parties continue to duck the basic challenges facing our nation.