Though her fans will probably bridle at the observation, Tuesday’s Democratic presidential debate made it clear that Sen. Elizabeth Warren (D-Mass.) is not really a health-care wonk.

Warren’s appeal to voters is as the thinking man’s Sen. Bernie Sanders (I-Vt.). Among a certain sector of the electorate — highly educated, urbane, prone to reading “explainers” — the pedantic glamour of the Harvard professoriate blurs her radical edges and limns her most pedestrian pronouncements. These are the sort of people who praise Warren over Sanders because she really knows her stuff.

Yet consider her answer on Tuesday night when Marc Lacey, a New York Times editor, asked her about health-care insurance: “You have not specified how you’re going to pay for the most expensive plan, Medicare-for-all. Will you raise taxes on the middle class to pay for it, yes or no?”

The former professor sounded like a freshman who hadn’t done the reading. Warren ambled between heart-tugging anecdote and amiably unobjectionable generalities — “Look, the way I see this, it is hard enough to get a diagnosis … what you shouldn’t have to worry about is how you’re going to pay for your health care after that.” She didn’t attempt to answer the question, except to insist that the only people who will pay for her new plan are the rich and big corporations. As real wonks know, that math doesn’t work.

The top 1 percent garner about 20 percent of national income, which, coincidentally, is close to the share of national income America spends on health care. But according to the nonpartisan Tax Policy Center, that top 1 percent of taxpayers collectively took home about $1.9 trillion in after-tax income, which wouldn’t begin to cover the estimated $32 trillion per decade cost of Medicare-for-all even if every penny were confiscated. You could make the math work by applying equally confiscatory rates to the top 5 percent, except people don’t work just to hand all their money over to the government; a 100 percent tax rate, or even something close, would hardly raise any money at all.

No, paying for Medicare-for-all would entail taxing the dickens out of the middle class. You could argue, as Sanders has, that the middle class would still be getting a good deal, because they’d (eventually) save so much on whatever they or their employers are now spending on insurance premiums. What you can’t argue is that Medicare-for-all is possible without those tax hikes. At least, not while retaining your wonk cred.

At the presidential debate, when Pete Buttigieg, the mayor of South Bend, Ind., called Warren out for her evasions, she scrambled to invoke her professorial credentials, saying, “I’ve been studying this, you know, for the biggest part of my life … why people go bankrupt.” And here Warren is making the same mistake that many of her supporters do: thinking that “wonkiness” is a generalizable characteristic rather than a specific proficiency.

It’s true that Warren’s best-known research suggested that illness causes more than half of all bankruptcies. Her critics, including me, have pointed out that her study has fundamental methodological problems and that the results she found are far higher than in other, more careful work. Nonetheless, Warren unquestionably knows a lot about bankruptcy.

That knowledge may have fooled her, and has definitely fooled many of Warren’s followers, into thinking that she therefore knows a lot about fixing the health-care system. But in a given year, only 0.2 percent of the American population declares bankruptcy for any reason; the percentage who face medical bankruptcy is even lower. So even if you knew everything about bankruptcies due to illness, you still wouldn’t know that much about the problems patients face in the U.S. health-care system. Nor would you know much about the other difficulties that reformers must tackle, such as “How do we pay for it?” and “How do we get our reform past hospitals, doctors, nurses and other mediagenic lobbying groups?” and “How do we cut costs without critically disrupting care?”

The fact that these problems haven’t been solved, despite the Obama administration’s best efforts, tells you they’re very hard. I have my doubts that a viable solution exists, at least in the near term. But I’m quite certain that if the problems are going to be fixed, it will be by someone who starts by carefully digging into the evidence and then works their way forward to the conclusion, rather than the other way around — by a real health-care wonk, in other words, and not just someone who plays one on TV.

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