Frequently people use the metaphor of "levels" to describe different modalities of understanding. You have almost certainly hear someone say, "That is wrong on so many levels"? It is a cliché, and it is intended (usually) to be humorous, so I don't bother too much about what it means. But I am curious about the use of the metaphor of levels in general. It was nicely lampooned in one of my favourite scenes from "Friends." Phoebe was preparing to move out of the apartment with Monica, and Ross was telling her that she ought to inform Monica of her plans.
"I think on some level, she already does know it," Phoebe responds.
"How?" asks Ross. "She doesn't know that you've changed your mailing address. She doesn't know that you're sleeping at your grandmother's every night. She doesn't know that you already have a lease on another apartment."
"Well, maybe not on those levels," Phoebe admits.
The obvious question is, what could Phoebe mean by saying Monica already knows it "on some level"? It can't mean she knows part of it; that wouldn't be a level, but a section. Levels cover the same area, but overlap completely. They are often used when dealing with literature, which can be understood literally or metaphorically. The story of Little Red Riding Hood is literally about a girl being attacked by a wolf, but it could be understood metaphorically as a story about sexual predators. (Actually, I don't know what it is a metahpor for, but let's just ignore that for a moment.) It makes sense to describe these as two different "levels" of understanding, because they both encompass the whole story, but they interpret it within an entirely different framework. If one wanted to apply a Marxist interpretation, that would be another level as well.
So it doesn't make sense to say that Monica doesn't understand that Phoebe is moving out "on the level of" she sleeps at her grandmother's apartment. That's not a level; it's an aspect. It isn't the complete story on a different layer, but rather a segment of the story on a very literal layer. Arguably, Phoebe could mean that Monica knows it on an intuitive level -- that she was aware of what was going on, but wasn't conscious of her awareness. That would be "knowing it" on a different level: fully grasping it, but not in a way that she could discuss it.
I'm not sure, but I suspect that most of the time people use levels in this metaphorical way, it doesn't make much sense. I am as guilty of it as anyone. The use of "levels" to describe knowledge has entered the popular idiom and it just sounds right a lot of times even when it isn't really the best word, just as people intuitively use "cool" to describe anything good. (I hope to write a future entry on coolness, which I think is a very interesting concept.) Of course, people understand its meaning in context, so, arguably, "levels" is just as good as, perhaps even better than, other word choices that are more logically consistent. I try to resist using popular idioms like this, and I often find myself struggling to express the concept in other words. Still, I think it's a good habit to get into. Using clichéd words is easy and can make one's meaning clear in the short run, but I think in the long run it tends to become so broad as to be meaningless. People who speak in clichés often end up saying nothing meaningful, the way corporate mission statements repeat business clichés without conveying any content. Besides, I like to give my mind the exercise of trying to think about what I actually what to express, rather than just letting the words fall out. That seems the right thing on so many levels.