Greg Mankiw has an interesting column on the public plan option; you've already seen related points on his blog and on MR.
Today I'm interested in a slightly different question, namely the potential benefits of monopsony. Imagine a benevolent single buyer of health care services. Forget about whether or not it could be a government; let's just focus on the logic of the model. I can think of a few scenarios:
1. The buyer bargains down price and suppliers in turn lower quantity.
2. The buyer bargains down price and the monopolizing suppliers respond by expanding quantity. The monopsonist moves us to a more competitive solution. Note that under this option the direct institution of more competition could have the same effects.
If #2 is true, you might expect supply restrictions to be an important issue. That is, the people who favor monopsony should also favor greater competitiveness on the supply side. Yet this does not seem like a current priority. I hardly ever see talk of deregulating medical licensing, allowing paramedics and nurses to perform more basic medical functions, or abolishing other entry restrictions. I do recall that an earlier version of Obama's plan, struck down by Congress, would have created a nationwide insurance market. There was no big fight, either in the administration or in the blogosphere.
Those who favor monopsony might have another model in mind. In this model there are many medical suppliers but each supplier still has a fair degree of ex post monopoly power. Search costs, non-transparency, lock-in, and consumer irrationality can generate this kind of result. And in these models allowing for more entry needn't much help the basic problem.
Under #2, which other policies will help set this market right? What are the possible policy substitutes for monopsony?
And in #2, what happens if a monopsonist third party payer bargains prices down? What are the offsetting quality responses? Are monopsonists good at bargaining for higher levels of quality? Or might the all-in-one, bureaucratic nature of the monopsonistic enterprise mean that the monopsonist is very good at bargaining over price (measurable) and very bad at bargaining over quality (harder to measure and verify and we already know there is irrationality, non-transparency, lock-in, etc).
If we put monopsony in place, can a version of the Card-Krueger monopsony model apply to medicine, namely a welfare-improving minimum wage for doctors, albeit at a very high level? That would mean we don't want the monopsony to economize on how much we spend on health care.
For all the recent writings on health care, these questions remain underexplored. Comments are open, but today I'm not interested in the usual bickering about public vs. private sector. I'd like to hear about the logic of monopsony.