If we keep taxes low on America's high earners, the terrorists win.

Or at least they'll have a point.

The way we've compartmentalized our current tax debate - and kept it hermetically sealed from the fact that we're a nation at war - is evidence of the moral rot from which our enemies say America suffers.

Listen to the back-and-forth in Washington. Nothing would be different in the way this debate sounds if we were not borrowing $150 billion a year to fund more than 100,000 troops in Afghanistan and Iraq.

"Where's the outrage?" is always the last gasp of those losing the debate, but this should shock us all. Never before have Americans made it a national priority to keep taxes low on the best-off at a time of war. This argument is MIA today because, for 99 percent of us, the wars that presidents of both parties have deemed critical for national security don't touch our lives at all.

As Robert Gates has pointed out, "the Iraq and Afghanistan campaigns represent the first protracted large-scale conflicts since our Revolutionary War fought entirely by volunteers. Indeed, no major war has been fought with a smaller percentage of this country's citizens in uniform full-time."

Less than 1 percent of us serve today.

To be fair to Democrats, a majority in the House and Senate wanted to let tax cuts for the top expire. But since we don't have majority rule in the Senate, this didn't suffice. Why couldn't Democrats have hammered this home? Why didn't they say there's something wrong when 41 Republicans can mandate an immoral outcome - immoral not because tax relief for the best-off is inherently wrong (it's obviously not), but because it's wrong at a time of war and surging debt?

"There's something preposterous about a nation that has been 'at war' for almost a decade, yet insists on remaining completely oblivious to the implications," says Andrew Bacevich, the retired army colonel and Vietnam veteran who now writes and teaches at Boston University. Bacevich lost a son in Iraq.

"What's troubling is the moral aspect," he told me. "Are we citizens or are we not?"

When I make this case - most recently in cable news "debates" - conservatives won't engage. They act as if I'm beaming in with arguments from another planet.

"How can we talk about this as if the economic debate is totally segregated from the fact that we're at war?" I say.

"The real war is the class war being waged by Democrats against job creators," runs a typical reply. Can this resort to the same old talking points be serious?

One conservative wrote this week that "the politics of higher taxes now rests almost purely on stoking resentment." But that's absurd. I'm in the top marginal bracket and don't resent myself a bit.

Isn't it obvious that the question is how the burden of war should be shared?

"We're not spending that much on the wars anyway," is a final GOP argument I've heard. Huh? Since when did $150 billion a year - more than a trillion all told on both wars - not count as "a lot"?

All of it borrowed.

During the Civil War, the ability of the well-off to buy their way out of service actually made them fear a backlash and helped spur passage of America's first (temporary) income tax. Today, by contrast, there's no stigma attached to calling for extended tax relief for the top while hiring poor people (or private armies) to do the dirty work of empire.

Why is this an orphan argument? Democrats are either blind to it or don't want to remind folks of unpopular wars. John McCain circa 2000 might have made this case, back when he fought the original Bush tax cuts for their tilt to the rich. And that was before our endless wars began. But no one's seen that John McCain for years.

I never thought I'd say this, but Sarah Palin is my Hail Mary pass.

Suppose Palin said tomorrow that she'd talked it over with her son, the Iraq veteran, and concluded that now is not the time to devote $120 billion over the next two years to ease taxes for comfortable families like her own. The money could be better used on deeper payroll tax cuts that would really boost jobs, or to help pay for our wars. She'd call us to our highest values as nation, saying we're all in this together.

Does anyone doubt that if she tweeted thus the impact would be thunderous?

What about it, Ms. P?

Matt Miller, a senior fellow at the Center for American Progress and co-host of public radio's "Left, Right & Center," writes a weekly column for The Post. He can be reached at mattino2@gmail.com. Follow him on Twitter at @mattmillernow.