August being America’s silly season, a lot of folks seem to feel compelled to come up with the silliest ideas they can think of and pop them on the rest of us. Some of them are good for a laugh, some are infuriating and some can scare the living kishkes out of you. And some can do all three.

First prize in that “all three” category goes to a certain pernicious theory that’s making the rounds lately, purporting to explain the ugliness of the great Debt Ceiling ballyhoo in Washington. It goes like this: It’s Congress’s fault, and the numbers prove it. Scientifically, no less.

Seriously. The theory is that Congress has gotten polarized because the parties have moved to the extremes and forgotten how to compromise. Democrats have moved way to the left, Republicans have moved to the right and the middle has disappeared. The scientific proof is found in a statistical chestnut unearthed last winter by the well-respected and impeccably centrist National Journal. After examining the voting records of all 535 members of the House and Senate, they discovered that the most conservative Democrats were to the left of the most liberal Republicans. In the middle, where moderates once met, there’s nothing left but a scorched, empty field.

Gone, we learn, are the moderates of yesteryear, the conservative Blue Dog Democrats from the South and the liberal Gypsy Moth Republicans of the Northeast who overlapped in the middle and made compromise possible. Now everyone is either far left or far right, and stuck there. Hence Congress is broken.

Of course, everyone has their favorite whipping boy, and there’s nothing that people love to hate more than Congress. This theory is particularly compelling because it finds fault with both sides, which is the fair, objective way to analyze these things. It also has the soothing effect of letting everyone off the hook. If it’s everybody’s fault, then it’s nobody’s fault.

The problem is that it’s wrong. Not all of it, mind you — just the important part.

It’s true that the two sides don’t overlap much anymore. Yes, the numbers do show an empty space between the most liberal Republicans and the most conservative Democrats. What’s false is the idea that each side has moved toward its extreme wing, Republicans to the right and Democrats to the left. In fact, Democrats have moved substantially to the right in recent years. But Republicans have moved even further to the right.

Identifying the parties’ shifts by examining their positions on the issues is tricky, because you need some historical memory to see what’s changed. Back in the days when Democrats were still the left, they spoke of the poor as people who need our help and poverty as something to be defeated by declaring war. Government was how people united to solve big problems with big solutions: Medicare, student loans, flying to the moon.

Republicans, the party of the right, urged caution, responsibility, protecting individual liberty and free enterprise. Helping the poor was the task of charity, with government as a last resort. Government’s role in tackling big problems was not to fix things but to orchestrate reform through the private sector, like President Nixon’s ill-fated health-care reform. And then there was President Eisenhower’s Interstate Highway System, one of the biggest socialist undertakings of all.

And now? Democrats fight to preserve government’s last-resort aid to the poor while Republicans ask whether the poor are “deserving” of help. Democrats fight to solve problems with Republican-style market solutions, like cap-and-trade carbon reduction and the Romney health-care reform that President Obama brought to Washington, and Republicans attack each new idea as socialist tyranny. The basic dividing line is no longer government’s proper role, but its very legitimacy.

You can see the lopsided shift in the National Journal’s congressional voting statistics. Each lawmaker’s individual votes are labeled left or right and then averaged together to reach a rating on a 0-to-100 scale. Every member gets two scores, one where 100 is liberal and the other where 100 is conservative, so someone who ranks 70 on the liberal scale gets a 30 on the conservative scale. Got it?

Now, if each party had shifted toward its extreme, they should approach each other somewhere around 50. Not so. The meeting point is around 60 on the conservative side.

In the Senate, for example, the most liberal Republican is Susan Collins of Maine, who scores 62 on the conservative scale. The most conservative Democratic senator, Ben Nelson of Nebraska, scores 57.7 — on the conservative scale. Nelson is one of three Democratic senators who rank above 50 on the conservative side. In fact, there are eight Democrats whose liberal score is below 60, putting them near the 50-yard line. No Republicans score below 60 on the conservative scale.

The numbers in the House are pretty much the same. The old Blue Dog Democrats’ Caucus hasn’t disappeared, by the way; it still has 26 members, 15 of them outright conservatives. No Republicans are remotely liberal.

In other words, the center didn’t disappear. It just moved. The Republicans moved rightward from their old space on the right. The Democrats moved toward them and filled the space where the center used to be. What used to be called the right — small government, free-market solutions — is now dead center. What used to be called the middle — tolerance of all views, devotion to compromise — is now the left. You can tell it’s become a partisan position, because the new conservatives, having moved to the right of the right, deride that sort of tolerance as “moral relativism.”

As for the classic Democratic positions — redistribution, robust government intervention — they’re now off on the far left.

And where is the mainstream Republican right today? Well, we just got a taste of that one in the hostage-taking crisis known as the Debt Ceiling. Which is, as noted above, either ridiculous, infuriating, terrifying or all three.

Contact J.J. Goldberg at goldberg@forward.com.