Dear Chuckles: the point isn't that Sarah Palin wasn't sure which "Bush Doctrine" Charles Gibson meant. It's that she clearly didn't know what it was by any definition. It's not even clear she knew that there was a "Bush Doctrine" until Gibson asked her that question.
As the always excellent James Fallows points out, Palin clearly knows less about foreign affairs than someone who simply follows the news reasonably closely.
And, Chuckles, let's look at those four "Bush Doctrines" you listed. The first, in June 2001, originated from you. But few besides your devoted fans ever heard of it, so can we dispense with that?
The last one you give, "the idea that the fundamental mission of American foreign policy is to spread democracy throughout the world," has long since been laughed out of the public dialogue. Bush has completely abandoned his earlier, exceedingly modest attempts to nudge authoritarian allies towards democracy or even towards less repression of critical speech. They were clearly window dressing at the time, but they gulled those who wanted to be gulled (not naming any names, Chuckles) that Bush's "behave, or I'll ram 'democracy' down your throat" approach to the world was part of a broader push for actual democracy, rather than a transparently flimsy justification for saber-rattling and war.
So nobody takes that one seriously anymore, and the idea that "If I were in any public foreign policy debate today, and my adversary were to raise the Bush doctrine, both I and the audience would assume -- unless my interlocutor annotated the reference otherwise -- that he was speaking about the grandly proclaimed (and widely attacked) freedom agenda of the Bush administration" is total bullshit. Nobody with any connection to the real world would assume such a thing.
You might, Chuckles, but few have accused you of being particularly tethered to the real world.
The second one, the "Either you are with us or you are with the terrorists...[f]rom this day forward any nation that continues to harbor or support terrorism will be regarded by the United States as a hostile regime" doctrine from just after 9/11/01, was (your choice) superseded by the third Bush Doctrine you name, or died a quiet death when Pakistan became Osama bin Laden's safe harbor, which it remains to this day.
The third one, the one used to justify the Iraq war, was of course the one that Gibson was referring to: the notion that we could initiate preventive war against another nation, well before there was any reason to believe they constituted an imminent threat to any other country. That one was not only used to justify the Iraq invasion, but was also alive and well last year when the Bush Administration was saber-rattling at Iran. The threat from Iran wasn't going to be imminent during the remainder of the Bush Administration, but factions within that Administration (can you say Cheney? I knew you could!) wanted to bomb, bomb Iran anyway.
So even if we assumed that Palin actually had any sort of clue about the Bush Doctrine, that's the one she would have had to consider the operative one.
But she obviously had no clue at all. The question implicit in Palin's confused look wasn't "which Bush Doctrine?" but "there's something called a Bush Doctrine?"
Give it up, Chuckles.
And you too, Michael Abramowitz.