Why is it so hard to put a number on Americans without health insurance?

George Will and Megan McArdle take issue with the Census Bureau's figure from 2008 that 46 million Americans are in need of health insurance. They also disagree with President Obama's statement in his speech to Congress last week that there are "more than 30 million American citizens who cannot get coverage." Will estimates that there are "perhaps 20 million persons who are protractedly uninsured." McArdle suggests that a better statistic would be "more than 15 million" Americans.

Anthony Wright has a good response on TNR. I pretty much agree with him and frankly don't have much to add to what he says.

The debate over these statistics can be a red herring. There's a reason why conservatives and libertarians are taking a different stance on how to interpret the statistics than liberals. You can't interpret the data without expressing your ideology. If you're a liberal, you're likely to view the number of Americans without insurance as a crucial fact, maybe the most important fact in the whole health-care debate. If you're a conservative, you're likely to see that statistic as a smokescreen covering up the reality of the situation.

For instance, Will thinks the statistics are misleading because they gloss over the transitory nature of being insured. He says the 46 million figure is just

a "snapshot" of a nation in which more than 20 million working Americans change jobs every year. Many of them are briefly uninsured between jobs. If all the uninsured were assembled for a group photograph, and six months later the then-uninsured were assembled for another photograph, about half the people in the photos would be different.

But Will bizarrely implies that his observation only mitigates the problem. It's arguably worse than the statistics suggest, since a "snapshot" fails to convey the fact that people who are insured right now need to worry about whether they'll be insured in the future. Wright points out: 

When just looking at a two-year period, far more people--nearly 1 in 3--find themselves uninsured.

It's understandable that opponents of health-care reform want to make the number of uninsured seem as insignificant as possible by quibbling over which ones we should really be counting. (Illegal immigrants? Legal immigrants? Poor people who aren't on Medicaid? Households making $75,000? $50,000?) It might be comforting, as Wright puts it, "to "think of the uninsured as a discrete population, one that can be marginalized." But the real problem is much broader: our health care is contingent on something as unreliable as employment, with only an incomplete safety net for Americans in need. Those of us who feel strongly that this is a grave problem aren't going to have our minds changed by the pseudo-statistical debate over how many uninsured Americans actually matter.