The lesson of Dave Brat’s victory over Eric Cantor last week is being missed: In all pundits’ talk about immigration, no one has stopped to point out that Brat boldly grabbed the third rail of American politics, ripped it off the tracks, and beat Cantor with it.

George W. Bush, Michele Bachmann, and Rick Perry all rhetorically touched entitlement programs and lived, but I’ve never seen a politician tell the plain, actuarial truth the way Brat did and get rewarded for it. Republicans should be overjoyed that they can finally shout about underfunded social programs. Instead, the only lesson they’re learning is that the candidate who loses is the one who’s amnestiest.

“Add up Social Security, Medicare, Medicaid, and the Bush prescription drug plan,” Brat told his audiences, and you get “$127 trillion in unfunded liabilities. Unfunded — that’s not the cost of the program, that’s just the unfunded part in law. Right? All these programs are insolvent. They’re bankrupt. We can’t pay for them. By 2048, not that far off, those four programs alone take up the entire federal budget, the entire federal budget. So no more military spending, no more judiciary, no more anything.

“Has any leader that you know on the Republican side or on the Democrat side mentioned that number to you, in public?” he asked. “I haven’t heard anyone ever say ‘yes’ at a talk yet.”

In one video of a Brat appearance, the bald and graying heads in the audience that had been nodding along go still when he hits those points. But they voted for him anyway, voted for the man who didn’t tell them what they wanted to hear. That’s impressive, and makes it hard to dismiss Brat by saying that his version of RINO-bashing is just a new take on the old Washington-is-broken, throw-the-bums-out method of campaigning.

Now, I’m as thrilled as anyone to see liberty-minded conservatives hold a double-talking, big government Republican like Eric Cantor accountable. But the message they’re trying to send keeps getting confounded by immigration politics.

Plenty of Tea Party folks tack immigration onto their list of Constitutional and fiscal concerns. But can Brat really do the same without undermining himself? An economist by training, Brat identifies with the Milton Friedman/Chicago School; he preaches free markets, denounces crony capitalists, and promises to “unflinchingly uphold” the Republican creed. Then he makes himself ridiculous by trying to explain his position on immigration in those terms.

The idea that opposition to immigration, legal or otherwise, is somehow the authentic Republican position is arrant, ahistorical nonsense, and it’s especially pharisaical coming from a free marketer. The Republican Party was formed in 1856 as an alternative to the anti-immigrant Know Nothing Party and the pro-slavery politics of Franklin Pierce’s Democratic Party. The call to attend the first Republican National Convention went to out to everyone who favored limiting or abolishing slavery and “restoring the action of the Federal government to the principles of Washington and Jefferson.”

The name of the party was meant to reflect those republican principles of the founders. James Madison — Brat’s a big Madison fan — defined “the republican principle” specifically as a limit on the sort of factionalism that we would now call the tyranny of the majority. In Federalist No. 10, Madison argued that in a democracy “the majority, having such coexistent passion or interest, must be rendered, by their number and local situation, unable to concert and carry into effect schemes of oppression” on their fellow citizens.

The native-born children of illegal immigrants have the exact same claim to citizenship that anyone else does: Section 1 of the Fourteenth Amendment. Redefining the Constitution to eliminate “birthright citizenship” would create out of them an underclass of stateless refugees. You might want to deport them, but what obligation would any other nation have to admit these American strangers? To me, that is plainly a scheme of oppression against a class that has always been recognized as American. It is, in other words, anti-republican.

Brat leveled the always malleable charge of “amnesty” against Cantor for favoring a path to citizenship for the children of illegal immigrants brought here at a young age by their parents. He’s got something of a point here, especially speaking for a party that stands for law and order. Still, amnesty means a pardon for a conviction, and I’m not sure what syphilitic idea of justice could convict children for the sins of their parents.

Brat works his opposition to illegal immigration into his general theme of opposition to crony capitalism. That juxtaposition has drawn a lot of attention for its novelty, but it would be more effective, or coherent at least, if he wasn’t trying to argue that restricting the labor pool was somehow pro-free market. “Big business gets the cheap labor and the rest of us pick up the tab,” Brat says.

Milton Friedman would laugh at Brat’s complaint about immigration’s (brief, barely discernible) depressive effect on wages. A better summary is that big business gets the cheap labor and the rest of us pick up the cheap products and services.

Of course businesses “would prefer to pay lower wages rather than higher wages,” Friedman once told someone making a similar point. “You’d like to pay lower prices for the things you buy rather than higher prices. Of course. That’s the whole system. That’s exactly the system.”

Brat aligns himself with Friedman, but Friedman was in favor of illegal immigration, owing to the massive productivity gains it produces. “Look, for example, at the obvious, immediate, practical example of illegal Mexican immigration,” Friedman once said. “Now, that Mexican immigration, over the border, is a good thing. It’s a good thing for the illegal immigrants. It’s a good thing for the United States. It’s a good thing for the citizens of the country. But, it’s only good so long as it’s illegal.”

Free immigration, as the U.S. had before 1914. “was a good thing,” too, Friedman added. The problem with unrestricted immigration today, as he famously said, is that you can’t have free immigration and a welfare state both.

So here’s an idea, one the Democrats usually reject out of concerns for equality, but one that I think a lot of immigrants would accept. How about a path to permanent legal guest worker status, not citizenship? Workers would pay payroll taxes, and be eligible for no benefits and no citizenship. There’d be some fraud, but the taxes could be set to cover the cost.

Brat ought to tell us if that counts as amnesty.