It is worth drawing a distinction between two lines of attack that John McCain pursued in last night's debate. The first is the one that will garner more attention from Saturday Night Live tonight and the comedy shows this week, and it consisted of McCain saying that his opponent, Barack Obama, is "naive" and does not "understand" that we live in a dangerous world. By my count, McCain used this line of attack (and the U-word), six different times (tactics vs. strategies, the surge, Pakistan pre-Musharraf, a connection between Iraq and Afghanistan, negotiating with Iran, Russian aggression, the importance of Iraq). The second line of attack consisted of McCain hinting that Obama was an empty suit, a politican who blows with the wind and does things for political gain instead of the right reasons. Two examples of this strategy (or is it a tactic?) would be McCain's claim that Obama only boarded the anti-pork bandwagon once he started running for president, and his (McCain's) comments on the lack of hearings held on Afghanistan by Obama's Senate Foreign Relations subcommittee. This attack, at least to one debate watcher, was much, much more effective.
There are a few problems with McCain's 'Obama-does-not-understand-the-world' assault. For starters, McCain is incapable of saying things like this without coming across as incredibly condescending (especially, one would imagine, to people under the age of 50). And second, these diatribes do not really fit with one's impression of Obama. If nothing else, the Illinois senator comes across as extremely smart and even professorial, and thus it does not make much sense to think that people are really going to question his understanding of whether Russia attacked Georgia first. Which brings us to the third problem, namely that McCain used the "understand" line much, much too often. It is one thing to say that your opponent does not understand the importance of Iraq to the wider Muslim world; it is quite another to call into question his basic knowledge of the political situation in countries that are all over the news.
I would argue that McCain's second line of attack is/was more effective. It plays into what I think is probably Obama's greatest liability, i.e. the question of whether he is just a celebrity politician without gravitas or character. The subcommittee moment was the only time during the entire debate that I winced, and Obama's reply came across as insufficient. The other advantage to McCain's circulation of this meme is that the Arizonan is able to voice it without appearing old and grumpy. This perhaps has less to do with the criticism itself than it does with McCain's particular personality, but that in itself is irrelevant.