One thing I agree 100 percent about with Chris Bowers and Atrios is that it would be an excellent thing if the “progressive block” on health care were regarded as a credible threat to derail insufficiently progressive. You can read their posts for longer explanations of why such a threat would be good, I don’t disagree with them about any of it.
On a related note, what should we do if Russia launches a sudden unprovoked nuclear attack aimed at American population centers? I assume Russia won’t do that. And I assume that one reason they won’t do it is that the United States has credibly threatened to respond to such a move by using our second strike capabilities to decimate Russian population centers. That’s a very good thing. The threat, and its credibility, are important and useful. Nevertheless, to actually carry out the threat would be to unleash an enormous and entirely pointless slaughter. Flattening Moscow won’t bring back New York, all it will do is add to the death toll. The threat is good, but carrying the threat out would be wrong. But of course if you acknowledge that, you’re not credible.