I’m baffled by liberals who don’t actually support Obamacare themselves—they want single-payer—but are furious at Republicans for voting against it. (Several comments here illustrate the phenomenon.) Let’s consider the logic. A great many Republicans actually do oppose Obamacare for bona fide reasons. Others are indifferent, and some might opposite it only on partisan grounds while liking the law in principle. Which of these groups of Republicans do liberals think would have had reason to vote for the law?

Those who secretly liked the law were going to see it passed anyway by a Democratic majority—they got the policy they wanted without having to risk blowback in a Republican primary. You’d have to be extremely idealistic to believe that taking a serious political risk to make no policy difference is a prudent move. Indifferent Republicans faced an even starker calculus: risk your career for a policy you don’t care about at all or that you think has as much chance of turning out badly as well. Finally, Republicans who did oppose PPACA out of principle surely can’t be expected to have a reason to vote for the law anyway absent something to change the equation.

This was the ex ante logic, and it proved to be correct: any Republican who had voted for Obamacare would have faced the wrath of the Tea Party, and if he had survived past 2010, he would still have to survive a 2014 midterm in which even Democrats risk losing their seats over their association with the law and its disastrous implementation.

Liberals are so politically inert that I don’t waste much time criticizing them. The Democratic Party, to the extent that it’s liberal, wins nationally because the GOP is a basket case. The hard left, which knows that Democrats are about as neoliberal as the GOP, lives in a nonsense world in which puppet-wielding protesters shape policy, or would if only they built more and bigger puppets. I know some very well meaning, otherwise intelligent antiwar leftists who are nonetheless the most politically infantile people you will ever meet. Politics is just magic to them. (Some of this comes of drawing the wrong lessons from Alinsky and Gramsci—wrong lessons the activist right is now busy committing to memory.)

What drives liberals’ political inanity is the same thing that accounts for why the Tea Party can’t govern: just as the grassroots right is against a lot of things but doesn’t feel much urgency about figuring out what it’s realistically for, liberals go hot with rage over Republican bad behavior and stop there, indulging in outrage rather than thinking about how to change the GOP’s incentives.

The Obamacare saga is the clearest example of the left’s failure to think politically. Lefties defend a law that they don’t even like, and which cost the Democratic Party enormously in 2010 and looks set to do so again in 2014. This would be like conservatives defending Medicare Part D if it had caused Republicans to lose the House in 2004. To their credit, most right-wingers, even the hawks, have the good sense not to attack anyone today for failing to support the Iraq War in 2003.

The only way to get a party or a politician to act against its interest or its principles is to change what those interests or principles are through powerful incentives. Offer X in return for Y, and if X is a higher priority for the other party than not-Y, you will get your way. Such negotiation isn’t always easy or even possible—the alignment of interests (including self-preservation) and principle involved in Republican opposition to Obamacare may have been insurmountable. At that point, a politician or party has a choice: press ahead with the policy knowing that you will bear 100 percent of the blame if things go wrong, or put your wager on something else and bide your time on this issue until the other side is more tractable. Obama, Reid, and Pelosi made their choice—fair enough—and they’re living with the consequences. The Republicans did the only thing that made sense in their position; and now they might reap a reward.

Liberals can comfort themselves in one respect, however: the Republicans have blown opportunities as good as this many times before. That’s why Harry Reid is still majority leader.