TAXING THE RICH Democrats want to increase taxes on the rich to fund the looming fiscal gap, which is driven largely by soaring health costs. Republicans object, saying higher taxes create economic distortions, discourage work and impede growth. Last month, John A. Boehner, the House speaker, said that we should instead consider means-testing Medicare. But what does that mean?

Here is how means-testing might work. We could start by choosing some income threshold — say, $250,000 — and then require people over 65 with higher annual income to pay more in Medicare premiums than they do now. For example, for every $1,000 of income beyond the threshold, they might have to pay an extra $10 in annual premiums.

Sounds good, right? But notice that the economic effects of means-testing are much the same as a tax increase. This particular plan is like increasing the income tax rate by one percentage point for high-income seniors. It is only semantics as to whether the $10 is called a “tax” or a “premium.”

Indeed, means-testing could create more economic distortions than would broad-based tax increases. Seniors have more flexibility in how much they work than do typical Americans. In particular, for many people, the timing of retirement is discretionary. The higher marginal tax rates implicit in means-testing will induce people to leave the labor force earlier than they otherwise would. This would deprive the economy of some of its most experienced and productive workers.

BLINKERED OPTIMISM Democrats and Republicans generally have different approaches to controlling the growth of health care spending. Democrats often favor a top-down approach: a panel of experts set up by the recent health care law will decide which medical procedures are cost-effective and which are wasteful. Republicans tend to prefer a bottom-up approach: empower consumers to make their own choices, they say, and the power of competition among private providers will keep costs down.

One thing that the two parties share, however, is the belief that controlling health care costs is possible. Yet many economists believe that the rise in health spending is largely the result of medical advances, which prolong and enhance life at a high cost. Perhaps health spending will inevitably, and even should, keep rising as a share of national income.

This possibility raises a question: If health care becomes an increasing share of the economy, how will we allocate it, and how will we pay for it? That is, if controlling the cost of health care fails, what is Plan B?

That is a question that candidates from both political parties agree on as well: they all seem determined to avoid it.