The conventional wisdom about Mitt Romney’s choice of Paul Ryan as his running mate is that it sets the stage for a debate about the role of government in society, between Romney and Ryan as champions of small government and Obama and Biden as supporters of big government. Indeed, that’s the thrust of the lead story in the Wall Street Journal this morning. And it’s pretty clear why Mitt Romney wants to have this debate.

First, the politics: The choice of Ryan should be slightly encouraging to Democrats for one reason—it confirms what the polls and Nate Silver have been saying for months: President Obama is winning, though not by much. One of Romney’s options was to simply run against the incumbent, pointing to the bad economy and making a bland case for himself as some kind of business guru. Apparently that wasn’t working, so he decided to double down on the Tea Party and the idea of radically reforming government—something that he’s been distinctly bad at throughout the election so far.

In the longer term, Democrats should be worried, because Romney and Ryan have the better debating position. Their position is simple and superficially compelling: Government is bad. (Cf. the DMV—it’s state, not federal, and the one in Massachusetts works very well, but whatever; BATF; EPA; IRS; whatever agency your audience happens to dislike. Compare to Apple as if all private sector businesses were like Apple.) Government infringes on individual liberty. Cut down the government and we will have (a) more liberty, (b) more economic growth, and (c) lower taxes.

What do the Democrats say in response? Government is good at some things and bad at some things, and needs to be leaner and more efficient. Or people need government services to succeed. (Doesn’t that sound offensive as soon as you say it, even if it’s true?) Or there’s a moral obligation to redistribute income through the tax-and-transfer system. Or government isn’t really that big when you compare it to history. So taxes should go down for some people and up for some other people.

It’s all confused, half-hearted, and unconvincing. It reminds me of George Lakoff’s book Moral Politics. Lakoff does a brilliant job identifying the core of the conservative worldview (the Strict Father ethos) and explaining why it’s so compelling. Then he tries to explain how liberals could and should base their positions on a Nurturing Mother worldview. The problem is, I came away from the book thinking that the conservatives had won, because the Nurturing Mother ethos was so unconvincing.

Now, this certainly doesn’t mean that Obama will lose the election. Although commentators like to think we’ll have a real debate about the role of government, more likely this election will be just like every other one: it will turn on a handful of independent voters’ inchoate, irrational perceptions of which candidate better fits their inchoate, irrational notion of what the president should look like. (If you haven’t made up your mind already, you’re unlikely to base your decision on a considered reflection on the proper size of government.) And while Mitt Romney is pretty terrible on this dimension, Ryan adds a long list of other flaws to the ticket.*

But it couldn’t hurt for the Democrats to have a decent response to the small-government attack line, and that starts with having some kind of understanding of what the federal government actually is and does. As David Moss has written and as Simon and I discussed in White House Burning (mainly chapters 4 and 6),  the primary role of today’s federal government is protect ordinary people from risks that are beyond their control, be they poor health in old age or toxic chemicals in children’s toys. I don’t think ordinary people want to face all of life’s risks alone, and the private sector isn’t going to help them. (The insurance markets that work halfway decently, like auto, home, and workers’ comp, are all characterized by near-mandatory participation, one way or another.)

But you can’t make that case by just pointing to one program after another. First, most people don’t see themselves as beneficiaries of most programs (many people think that only the current elderly benefit from Social Security and Medicare, even though we all benefit over a lifetime perspective), so focusing on the program level just makes people think their money is paying for someone else’s benefits. (This is in part because many people think they are paying more in taxes than they actually are.) Second, it isn’t a rhetorical match for the Romney-Ryan small government message. Instead, President Obama needs to come up with a vision of what the government is for—one that he hasn’t already compromised away. Isn’t he supposed to be good at that sort of thing?

* What does it say that the Republicans’ poster boy for free markets likes betting on individual bank stocks in the middle of a financial crisis? Does he really think he’s smarter than the market?

This post was originally published at Baseline Scenario and is reproduced here with permission.