What Mr. Romney and everyone else should know is that the V.H.A. is a huge policy success story, which offers important lessons for future health reform.

Many people still have an image of veterans’ health care based on the terrible state of the system two decades ago. Under the Clinton administration, however, the V.H.A. was overhauled, and achieved a remarkable combination of rising quality and successful cost control. Multiple surveys have found the V.H.A. providing better care than most Americans receive, even as the agency has held cost increases well below those facing Medicare and private insurers. Furthermore, the V.H.A. has led the way in cost-saving innovation, especially the use of electronic medical records.

What’s behind this success? Crucially, the V.H.A. is an integrated system, which provides health care as well as paying for it. So it’s free from the perverse incentives created when doctors and hospitals profit from expensive tests and procedures, whether or not those procedures actually make medical sense. And because V.H.A. patients are in it for the long term, the agency has a stronger incentive to invest in prevention than private insurers, many of whose customers move on after a few years.

And yes, this is “socialized medicine” — although some private systems, like Kaiser Permanente, share many of the V.H.A.’s virtues. But it works — and suggests what it will take to solve the troubles of U.S. health care more broadly.

Yet Mr. Romney believes that giving veterans vouchers to spend on private insurance would somehow yield better results. Why?

Well, Republicans have a thing about vouchers. Earlier this year Representative Paul Ryan famously introduced a plan to convert Medicare into a voucher system; Mr. Romney’s Medicare proposal follows similar lines. The claim, always, is the one Mr. Romney made last week, that “private sector competition” would lower costs.

But we have a lot of evidence about how private-sector competition in health insurance works, and it’s not favorable. The individual insurance market, which comes closest to the conservative ideal of free competition, has huge administrative costs and has no demonstrated ability to reduce other costs. Medicare Advantage, which allows Medicare beneficiaries to buy private insurance instead of having Medicare pay bills directly, has consistently had higher costs than the traditional program.

And the international evidence accords with U.S. experience. The most efficient health care systems are integrated systems like the V.H.A.; next best are single-payer systems like Medicare; the more privatized the system, the worse it performs.

To be fair to Mr. Romney, he takes a somewhat softer line than others in his party, suggesting that the existing V.H.A. system would remain available and that traditional Medicare would remain an option. In practice, however, partial privatization would almost surely undermine the public side of these programs. For example, one problem with the V.H.A. is that its hospitals are spread too thinly across the nation; this problem would become worse if a substantial number of veterans were encouraged to opt out of the system.

So what lies behind the Republican obsession with privatization and voucherization? Ideology, of course. It’s literally a fundamental article of faith in the G.O.P. that the private sector is always better than the government, and no amount of evidence can shake that credo.

edit- (and I would add the profit motive too—or mostly) 

In fact, it’s hard to avoid the sense that Republicans are especially eager to dismantle government programs that act as living demonstrations that their ideology is wrong. Bloated military budgets don’t bother them much — Mr. Romney has pledged to reverse President Obama’s defense cuts, despite the fact that no such cuts have actually taken place. But successful programs like veterans’ health, Social Security and Medicare are in the crosshairs.

Which brings me to a final thought: maybe all this amounts to a case for Rick Perry. Any Republican would, if elected president, set out to undermine precisely those government programs that work best. But Mr. Perry might not remember which programs he was supposed to destroy.