A few days ago, I was puzzled by the triple know in one of Gov. Mark Sanford's interviews:
Everybody's got their own value system, but to me, even if it's a place that I could never go, if I wanted to know that I knew that I knew, if that's more important to me than running for president, that's my prerogative as a human being.
I wondered whether he might be exhibiting an unexpected run of multiple-target speech errors (compare "the biggest self of self is self" from his earlier press conference). But a commenter, William Ockham, set me straight:
"To know that you know that you know" is a stock phrase in fundamentalist evangelical speech that's used to make an experiential claim about a supernatural reality. "To know" something is to have learned about it. "To know that you know" is to be certain of something you've learned. "To know that you know that you know" is to be certain of something because you learned it by experiencing it directly.
I think Sanford is saying that he went to Argentina because he believed that he had discovered true love and wanted to be certain of that, even if it went against his own moral code.
Today's news brings another example of the same construction, this time from Sarah Palin.
Kate Snow: Are you happy?
Sarah Palin: I’m extremely happy! I know that I know that I know this is the right thing for Alaska.
The boring and obvious interpretation would be that piling up instances of know that is just a form of emphasis by duplication, something like very very very or big big big. But we don't usually create emphasis by stacking up propositional complements. You can say "I hope hope hope that X" to mean "I really hope that X" – but "I hope that I hope that I hope that X" is just a strange form of emotional detachment, not an emphatic hope.
So William's analysis explains something that seems to need explaining. And the prevalence of religious examples among the web hits for "know that I know that I know" adds plausibility to his account.
But it's strange, if true, that each epistemological layer should add the specific non-compositional meaning he gives: "To know" something is to have learned about it. "To know that you know" is to be certain of something you've learned. "To know that you know that you know" is to be certain of something because you learned it by experiencing it directly.
Most linguistic theories allow for this kind of phrasal semantic suppletion, in principle — there's the special meaning of idioms, for example. But I can't think of any other examples like this one.