Josh Marshall at TPM is starting to get worried about John McCain's ability to control his temper.
Here's my answer to Josh. First, as I wrote back in August, McCain is caught on the horns of a dilemma: on the one hand, he considers himself an honorable man. But on the other hand, he considers himself duty-bound to be president, because he honestly believes that he is more qualified than anyone else, and particularly more so than Barack Obama, to protect this country. So he feels a responsibility to be president. Which has come to mean that he will do anything to become president, including lying about Obama, because if he doesn't become president, bad things will happen to the country. This conflicts with his sense of honor, and the contradiction is tearing him up.
But there's another contradiction that may be even more important, and more volatile. McCain has his flaws, like all of us. He's got a temper, he's reckless, he gambles (in many senses of the word), he's intellectually inconsistent. He uses his sense of honor to restrain himself. Nothing unusual there: that's what honor is supposed to do to a guy; keep his vices reined in. It might sound a little old-fashioned, but this is John McCain we're talking about here.
But for McCain, honor is even more important than a technique of self-restraint. It's also what saves him. Literally. His sense of honor is how John McCain grants himself redemption; it's how he forgives himself his failings. So when someone challenges him on a point of ethics, they aren't just challenging his integrity or his honor. They are challenging his salvation. It's enough to send a guy with a quick temper, like McCain, over the edge.