It's outrageous that a basic but critical question isn't being asked as a state government shutdown looms in Minnesota and as a standoff over the federal debt ceiling recklessly raises the specter of default.

Republicans and Democrats have drawn lines in the sand over spending cuts and taxes. Politicians are certain their particular mix of both are panaceas for a still-ailing economy.

But where is the evidence -- credible research, not talking points or anecdotal stories -- that these policies will actually work? More important, why isn't anyone demanding to see it?

The dearth of data guiding public policy is a national disgrace.

Americans would never settle for a doctor who prescribed medical care based on ideology rather than clinical data. Nor would they accept new drugs and medical devices going on the market without proof of safety and efficacy.

Yet there's a frightening disconnect when it comes to political decisions affecting the livelihood and well-being of millions. A nation that routinely second-guesses doctors with Internet research doesn't apply the same scrutiny to public policy.

Instead, voters accept at face value shopworn partisan pablum on the economy, taxes, education and welfare.

"It is a bizarre contrast. If your doctor acted like political commentators, he'd be drummed out of business,'' said Paul Gary Wyckoff , an economist and author of an increasingly influential 2009 book " Policy & Evidence in a Partisan Age .'' Wyckoff received his undergraduate degree at Macalester College.

Wyckoff's book performs a huge public service by pointing out the disconnect and a key reason why it happens. Politicians (and to be fair, journalists) don't naturally look to research the way doctors and scientists do. Their education -- often lacking in statistics -- doesn't equip them to do so.

Ideologues also may not like what they find. Wyckoff, who did dive into the data, concludes that the government isn't the powerful remedy for social and economic ills that liberals believe it to be. Nor is it the cause of these same problems, as conservatives believe. Wyckoff's review suggests:

• Economic stimulus programs generally arrive too late to mitigate recessions.

• Increased education spending moves the needle slightly on academic improvement but pales compared with family and socioeconomic influences.

• Overall research does not confirm the oft-cited correlation between small government and growth.

• The effects of tax cuts on economic growth are small, and may depend on public service levels staying the same.

• Cutting taxes and reducing public services at the same time reduces growth.

• The overall costs to states to attract new businesses often outweigh benefits. These policies also tend to benefit new residents, but not current ones.

Voters should always demand the best possible evidence from lawmakers. But the bar should be especially high for those willing to risk a shutdown or other extremes to enact their chosen policies.

"How do you know that?" is a reasonable request -- one that should be easy to answer for those with the right prescription.