AMERICANS WHO CHOSE to listen to, or read the transcripts of, three days of oral argument at the Supreme Court this week were treated to a challenging civics lesson on federalism, liberty and the limits and potential of government authority. Three points in particular struck us.

Sadly, even before the sessions on health-care reform had ended, some liberals were preemptively trying to delegitimize a potential defeat at the court. If the justices strike down the individual mandate to purchase health insurance, they said, they will prove themselves partisan, activist and, essentially, intellectually corrupt.

We share in the disappointment that the justices on both sides of their ideological divide are, for the most part, so predictable. That’s not, in the ideal world, how judging is supposed to work. But we also think there’s a kind of cynicism, or at least intellectual laziness, in asserting that this is an easy or obvious call — that no justice could possibly strike down the mandate out of honest, reasoned conviction. Solicitor General Donald B. Verrilli Jr. had his hands full defending the mandate, not because he’s a bad lawyer, but because it’s not an easy question.

If the federal government can force young adults to buy health insurance that they do not want, then what can’t the government do? That was the challenge from the mandate’s opponents. Liberal justices tried to come up with other cases where the government forces citizens to take affirmative action — to have pollution controls installed on their cars, to drive faster than 45 mph on the freeway. But no one has to buy a car, and you can choose to stay off the interstate.

Mr. Verrilli, in fact, had a persuasive response: The health-care market is different from all others because virtually everyone, like it or not, will become entangled in it. You can choose not to buy a car; you can’t necessarily choose not to be hit by one. If you end up in the emergency room, you will be cared for, as federal law demands. The government, already deeply involved in regulating the health-care market, has a legitimate interest in encouraging you to prepare for such an eventuality.

Given the court’s responsibility to err on the side of modesty and deference to elected legislators — who can be turned out of office if voters object to the health-care reform they design — the government’s argument is strong enough to carry the day. But it is not, as we said, a slam-dunk. We wouldn’t assume anyone who disagrees is a hack.

But — and here’s our second point — the idea that no American should go without health care, and that society as a whole should be willing to pitch in toward that end, strikes us as much more of a slam-dunk. There was, in some of the conservative argumentation over three days, a distressing undertone of me-firstism. Congress wanted to “capture” young people, attorney Paul D. Clement argued on behalf of the states objecting to the health-care plan, because they are “the golden geese that pay for the entire lowering of the premium.”

Well, yes, that is how insurance works: Premiums from young, healthy people help pay for the health care of older, sicker people. Some day the young people get old, and they, too, get cared for. You can look at them as geese getting exploited or as members of a community paying their share. It is, as Justice Ruth Bader Ginsburg pointed out, the principle underlying Social Security. Some people might think their 401(k) is big enough, so they’d just as soon not participate in that government program. But the United States decided as a nation that no elderly person should go hungry, and to make sure of that, every American worker must contribute into the system.

There would be other ways (as Mr. Clement agreed) to bring about this result in health care. Congress could have created a system of incentives to draw in young, healthy people. Or it could have enacted a broadly based tax to pay for the health care it wants to subsidize.

It didn’t — and this brings us to the third point — for a couple of reasons. One was that reform advocates didn’t seriously entertain the constitutional vulnerability of the mandate. But the bigger reason is a more familiar one in Washington these days: None of the politicians wanted to acknowledge the costs.

The pols love to bash insurance companies that exclude anyone with preexisting conditions. They demand that the companies charge less for old people than the actuarial tables would dictate. They want to give insurance to poor people who can’t afford it. But they, like their voters, don’t want to pay for the subsidies implied by any of those rules. When President Obama was running in 2008, he insisted he could deliver universal coverage without a mandate. Once in office, he found that wasn’t true. But he still didn’t want to use the word “tax,” and neither did anyone in Congress.

It’s the same wishful thinking embodied in Mr. Obama’s fervent pleas for “investment” in infrastructure, unaccompanied by calls to raise the gasoline tax. It’s the spirit of the budget of Rep. Paul Ryan (R-Wis.), which drastically reduces income tax rates without saying which deductions will be taken away. But you can’t get something for nothing, not even something as noble as universal health-care coverage.