Since the election, and in fact for some time before, pundits have been demanding that President Obama move to "the center." They don't have a lot of details, usually, about where that center is, and if they do suggest a detail it usually comes from one side of current debates, but they're all convinced that Obama needs to go there. But there's a reason that pundits can't describe this magical "center" better. It doesn't exist.

Obama can't move to the center, at least on the question of the economy, because there is no center. It's been his attempts to stand on that non-existent middle ground that have left him with nowhere firm to stand.

Usually I am all for discussing the middle ground. And I despise the "false dilemma" scam, which pretends that there are only two extreme choices when actually there are dozens of better ones between them. In most debates there is plenty of middle ground and only charlatans or fanatics deny that. But there are questions that actually do come down to only two choices, because the debate isn't just about practical details but about an underlying theory of how things work in the first place. Debates about strategy and tactics have many possible answers; debates about fundamental models often have only two. Our economic arguments are arguments about basic models of the economy.

Here are some questions that have no middle ground:

Does the Earth orbit the Sun or the Sun orbit the Earth?

Is disease caused by germs?

Do childhood measles vaccinations cause autism?

Can witches cause illness and harm livestock?

Does my car have anti-lock brakes or not?

These questions (and there are many like them) don't entertain compromise, and people who tried to offer "reasonable compromises" on the question the Earth orbiting the Sun and the Sun orbiting the Earth really came up with gobbledygook. It's one basic model or it's the other. And the theory we have about the basic way things work locks us into some pretty high-stakes decisions. Most of the time it doesn't matter whether I have anti-lock brakes or not, because I'm keeping a safe distance from the car in front of me and braking gradually. But if I suddenly need to stop in fifteen yards because the car in front of me on the highway just crashed, it matters a lot: either I need to step on the brakes as hard as I can, without fear of locking them, or I need to keep them from locking, even if it slows my braking speed. I really have to choose.

If vaccines really did cause autism, I would need to protect my (hypothetical) infant children from autism; since they don't, I need to protect them from measles, mumps, and rubella. If I believed in witches with magical powers, Rebecca Nurse would be a menace to everyone in Salem; since I don't, I think the real danger is Reverend Parris and his murderous witch hunts. There is no middle ground on the Salem question: either Rebecca Nurse or Rev. Parris is a serious public danger. There's no room for saying "both sides" are to blame. They can't be. And, as in the Salem case, attempts to stake out middle ground only help the wrong the side; if you say, "Witches are a serious public danger, but we should pay more attention to procedure when we try them," then you are supporting the witch trials. (And forget about the more cautious legal procedure. That's off the table.)

You can and should concede practical points to people on the other side of policy debates, when both sides agree on the basic underlying realities. But if you try to "compromise" by conceding that your opponent's basic model of reality is true, you have lost. If you concede that there are witches, people are going to get hanged. If you concede that vaccination "apparently plays some role which deserves further study" in childhood autism, then some kids are going to go unvaccinated and get the mumps, and some of those kids will die. Don't pump and pump your anti-lock brakes just to keep a backseat driver happy, if you're a couple yards from crashing into a pile-up. Just stop the damned car.

Our current political debates are full of basic arguments about underlying models, debates in which there is no middle ground for compromise. Either carbon emissions are causing global warming or they are not; what we should do next depends on the answer. Once one accepts that global warming is real, and caused by carbon emissions, there are all kinds of practical questions about what to do about that, and reasonable compromises, but there's no compromising with the belief that global warming isn't happening. There's no point in trying to find "middle ground" with the birthers, or more seriously with Republicans who want to eliminate the FDA. Either the FDA is necessary to protect public health or it isn't. But the most important either/or question at the moment is this one:

Does cutting government spending help or hurt an economy that's stuck in a bad recession?

It is very clear that the Republicans, especially the ones who were most triumphant the other night, believe that cutting government spending will improve the economy. John Boehner promised to focus on "cutting spending and creating jobs." It sounds like he believes that the first helps accomplish the second. Rand Paul, who is nothing if not firm in his beliefs, wants to balance the budget, right now. This of course, is what Herbert Hoover did the last time we had such a grievous economic setback. Of course, from the other point of view, frequently explained by Paul Krugman, this is the worst possible thing to do. Since recessions are caused by a massive overall cutback in spending (in fact, since everybody cutting back on spending at once is what a recession is), having the federal government suddenly enact massive spending cuts only deepens the problem. There is no middle ground between these theories.

There is no arguing this policy on the details. It is a choice between basic underlying models of how the economy works. John Maynard Keynes was basically right, or basically wrong. Milton Friedman either understood how recessions work, or he profoundly misunderstood them. We should hit the gas or we should hit the brakes. Hitting the gas and hitting the brakes at the same time is not one of the choices.

The economic middle ground that Obama is supposed to move to, the brakes-and-gas-pedal strategy so beloved by dignified, respectable, and fundamentally innumerate opinion columnists, is where he started out. The early 2009 stimulus package, which Krugman rightly decried as too small for the shortfall in national demand, was put together by people who couldn't decide if government spending was good or bad. The result managed to be the worst of both worlds: not enough to turn the economy around, but more than enough to worry people about the expense. And worse, as Krugman points out, Obama has a bad habit of conceding the "spending is bad" model:

I felt a sense of despair during Mr. Obama’s first State of the Union address, in which he declared that “families across the country are tightening their belts and making tough decisions. The federal government should do the same.” Not only was this bad economics — right now the government must spend, because the private sector can’t or won’t — it was almost a verbatim repeat of what John Boehner, the soon-to-be House speaker, said when attacking the original stimulus. If the president won’t speak up for his own economic philosophy, who will?

We have a choice. We can cut government spending, and throw cops and teachers and firefighters out of work, and see how that picks up the economy. Or we can take advantage of the ridiculously low current interest rates on government debt in order to spend on things which we actually need and can use: fixing our roads and bridges, improving our transportation system, funding crucial technological research before competitors like China get ahead of us. We can choose between a model in which government spends in the lean years and pays down debt in the fat years, or a model in which it cuts harder when times are tough. And President Obama can choose between championing one theory about how the world works or another. It can't be both. The Earth orbits the Sun, or it doesn't.

There is no middle ground. It has already collapsed under our feet.