I regret to concede this, but we have to start taking Donald Trump seriously.

And not just because the blowhard and real estate mogul turned GOP presidential candidate appears to be a serious contender, both within the Republican primary and the general election. But because — thanks to Trump's remarkably cavalier disdain for right-wing economic orthodoxy — voices on the liberal-left side of the spectrum are starting to have (highly qualified) nice things to say about him. "Trump happens to be right" on the economic issues, Paul Krugman declared at The New York Times, while Jonathan Chait and Sen. Elizabeth Warren praised Trump's willingness to hike taxes on the wealthy. Even ThinkProgress, my alma mater, has gotten in on the act.

So do Democrats and the left have something to learn from The Donald?

Yes. But there's a philosophic and a practical component to the lesson. And the former in particular needs to be parsed carefully, because it gets us into some dark waters.

Thanks to the rise of inequality, America's public discourse has been beset by a kind of holographic illusion. The cares and concerns of the bulk of American voters have been eclipsed by the particular conflicts that go on within and between the top tiers of the country's socioeconomic order. "Centrism" in U.S. politics is vaguely libertarian: some mix of economic conservatism and social liberalism, because that is the center of gravity for debates between most U.S. elites.

The crucial truth Donald Trump reveals about American politics is that the center of gravity for debates between Americans writ large is virtually the opposite: a mix of economic liberalism and social conservatism — what sometimes gets defined as "populism." The supply-side, no-tax-hikes-on-the-rich-ever orthodoxy of the GOP is actually incredibly unpopular with the American populace at large, and even among self-identified Republican voters. It's a testament to the hologram of elite consensus that an entire national political party can nonetheless adhere to it. Ideas that would actually be quite popular with the voting public are never even given a hearing in our politics, while ideas that are manifestly unpopular nonetheless manage to hang on.

"The influence of big-money donors meant that nobody could make a serious play for the GOP nomination without pledging allegiance to supply-side doctrine, and this allowed the establishment to imagine that ordinary voters shared its anti-populist creed," Krugman wrote. "But Mr. Trump, who is self-financing, didn’t need to genuflect to the big money, and it turns out that the base doesn’t mind his heresies. This is a real revelation, which may have a lasting impact on our politics."

Now, Trump's economic liberalism is pretty tepid, making him a pretty tepid populist. But it's nonetheless been enough to send the GOP establishment into fits of apoplexy, and even the supposedly everyman-friendly reformicons are keeping their distance. None of this has seemed to cost Trump much of anything in rank-and-file support.

The dark part is this: What Trump also reveals is that economic liberalism can sit comfortably alongside some poisonous impulses, including reactionary social conservatism, opposition to gay rights, racism, and ferociously anti-immigrant white nationalism. My colleague Ryan Cooper recently pointed out that this sweet spot in Western politics falls in the vicinity of the role fascism has historically played. While it would be going much too far to compare Trump to Hitler, analogies to wannabe authoritarians like Jean-Marie Le Pen, the former leader of France's main nationalist party, are probably instructive.

Which gets us to the practical question: Is there a way for people who prefer their economic populism to go along with a humane social leftism to capitalize on the split Trump has revealed (presumably through or in concert with the Democratic Party)? Yes, and broadly speaking, it's pretty simple: Give the voting public something they haven't seen in a while, and do Trump one better by going all in for economic leftism.

If The Donald wants to protect Social Security and Medicare, then Democrats and liberals should be for expanding them. Raise the generosity of benefits and lower the retirement age. If he's okay with some tax hikes on the rich, then be in favor of even bigger ones. By all accounts, the average tax rate on the top 1 percent could be doubled without harming economic growth in the slightest — while bringing in $450 billion in revenue annually. If Trump once said nice things about Canadian universal health care, then say them now. Advocate a single-payer health care system, or at least some big moves to bring ObamaCare closer to that model: Jack up the generosity of the subsidies, introduce a public option, and work to expand the exchanges to multi-state affairs or even one national exchange.

Another thing Donald Trump illuminates is that the class antagonisms of the middle and upper-middle class can extend both up and down the income ladder. American policy has focused on a targeted and means-tested welfare state to keep spending down, and because of anxieties about discouraging work. Democrats and liberals shouldn't fall into this trap. Instead, they should push for universal programs that benefit everyone regardless of their income level: a monthly allowance for every family raising a child; same for every adult whose full-time job is caring for another family member; same for anyone in school, etc. Push for paid leave and vacation for every last American, and hike the minimum wage.

And if all that requires a big uptick in deficit spending for a few years, great — the national and global economies need a big injection of demand.

Use economic liberalism to win back the everyday Americans you might lose because of your social liberalism. And use social liberalism — gay rights, more immigration, etc. — to win back as many elites as possible who might bolt because of the economic liberalism. And if you're still worried about holding on to big-money donors, then take a cue from Barack Obama and Bernie Sanders' campaigns and devote every last resource you can to pulling in the small-money donations.

In short, minimize the potential for American policy to be used as a symbol for class antagonism in either direction. Advocate a welfare state and a system of policies that embody, in their very design, the belief that all of us — rich, poor, white, black, brown, gay, straight, native, and immigrant — are in this together.