funny use of "naru"

[metablue]

I found a pic of a "hover cat" with this caption:
下はこうなっているんです！
shita wa kou natteirundesu.

http://s04inu.blog49.fc2.com/blog-entry-1690.html

My friend translated it as "This is what it looks like underneath." He tried to explain why there's a "naru" in there, but I didn't really get it.

He said:
This is a shortened form of "xxx natte iruno desu", and they mean "is xxx".
"shita wa kou desu" is a bit awkward. They're not quite interchangeable.

Can anyone explain?

[Jason]

He's right. There are a few things I'd like to point out about this. First let's break the grammar down more literally.

なる = to become
〜ている = to be in the state of
なっている = in the state of having become (something/someway)

So, literally the sentence says, "as for the bottom, it's in the state of having become like this."

2nd, a bit about the word こう. こう is an adverb, which means it modifies verbs, adjectives, and other adverbs. While it can be used to modify the copula だ/です, it's usually implied that you're actually referring to some other action. You can't use it as the Y in an X is Y type sentence. For example, here's a natural use of こう modifying です but note that it's actually referring to the previous action:

-にんじんをもっと小さく切って。 - "Cut the carrots smaller"
-こうですか。 - "Like this?"
-あ、いいよ。- "Yeah, that's good."

"Xは[こう/そう/ああ/どう]なる" has a sense of impermanence. It implies that "this is how it is from this particular viewpoint/in this particular situation." It implies that if you looked at from another angle/the circumstances were different, "how this is" would also change. This construct is very commonly used to describe something from a certain viewpoint, or a situation with certain circumstances. So if there was also a picture of the cat from above, the post might look something like this:

下はこうなっているんです！そして、上はこうなります。 - "This is how it looks from below. And this is how it looks from above."

Here's an example of it being used about a situation:

-やばいなぁ。また試験を落ちたの。- "Ah, crap. I failed another test."
-当たり前だろう？勉強しなきゃ、そうなるにきまってるじゃん！- "Well, duh! If you don't study, of course you'll fail (lit, it'll become like that)!"

[metablue]

Thank you! That helps a lot.

なっている = in the state of having become (something/someway)

So, literally the sentence says, "as for the bottom, it's in the state of having become like this."

The present tense was really throwing me off. I thought that "なっている" was "in the state of becoming".

It didn't make sense to me to say:
"as for the bottom, it's in the state of becoming like this."
because the cat's underside isn't changing.

Though taking the impermanence nuance into account, I guess the thing that is changing is your viewpoint, which in turn changes the way the cat looks. The cat's underside itself remains constant.

2nd, a bit about the word こう. こう is an adverb, which means it modifies verbs, adjectives, and other adverbs. While it can be used to modify the copula だ/です, it's usually implied that you're actually referring to some other action.

What is it modifying here? The only verb is the desu.

[Jason]

なっている = in the state of having become (something/someway)

So, literally the sentence says, "as for the bottom, it's in the state of having become like this."

The present tense was really throwing me off. I thought that "なっている" was "in the state of becoming".

Actually, now I'm not quite so sure. 〜ている has 2 slightly different meanings depending on the nature of the verb. If the verb is some action that can be done continuously from start to finish over a span of time, then it has the meaning "is doing X (for a span of time)." Examples of this are 食べている and 読んでいる. But if the verb is some action that the Japanese consider to be one that only takes place in an instant, then it has the meaning of "did X and is in the state of having done X"). Examples of this are 知っている,座っている, and 死んでいる. I'm not sure which category なる falls into though I would guess the 2nd which would mean my explanation of that part is right as is.

What is it modifying here? The only verb is the desu.

It's modifying です. The thing is the phrase is actually referring back to 切る in the frst sentence. It's different than using it directly as the Y part of an X is Y sentnece like, 「猫の下はこうです」. Y has to be either a noun phrase or an adjective (or a string of adjectives). Since こう is an adverb, it can't be Y. So, breaking down the structure of the sentence:

[X:猫の下]は[Y: ???]こうです.