What is the difference between なっている vs なった。

Question

What exactly is the differences between these two? To me, they both describe a change and would translate to "has become" in English.

I haven't been able to find any sources of questions about this so I would appreciate some help.

Answer 1

First of all, you should have a look at this answer which does a very good job explaining, among other things, the ている that you are asking about. As is mentioned in the answer, whether or not ている takes on this meaning representing a resulting state depends on the semantic content of the verb, among other things. The rest of my answer obviously only applies to cases where the resultative interpretation is appropriate. This is usually true of なっている.

The difference between the resultative なっている to the past tense なった is a lot like the difference between the English have become and became. On paper, these both just mean that the some event of becoming happened some time in the past - the difference is that the former places substantial emphasis on the state resulting from that event being relevant right now.

For example:

警察官になったけど、最終的に先生になった

I became a policeman, but ultimately became a teacher

Is fine with the right context; it sounds like these events happened in order in the past.

警察官になっているけど、最終的に先生になった (???)

I have become a policeman, but ultimately became a teacher (???)

This one doesn't sit well with me in either language. Of course someone could be a policeman and a teacher at the same time, but I ultimately became a teacher is weird here because it there's no clear ordering - it doesn't sound like the speaker is done being a policeman.

Edit: You mention in some comments that なった is sometimes used in ways that are most natural translate as have become in English. This is true, but ultimately just boils down to what is acceptable usage of different verb forms in Japanese.

彼は最近かっこよくなったね

Literally just means "you recently became cooler", although pragmatically this clearly means something that we would express in English as "you've gotten cooler recently". Ultimately this just comes down to the fact that there is not going to be a perfect 1:1 correspondence between Japanese verb forms and English verb forms, and that this structure happens to be more acceptable for this usage in Japanese than in English.

The resultative なっている doesn't map 1:1 either - a lot of usages most are most naturally expressed using the present tense copula in English.

窓が開いている (the window is open)

ガラスが割れている (the glass is cracked)

And this distinction isn't perfect in English, either. If I ask about going to a meeting and someone says

The meeting ended an hour ago

They are obviously trying to make a point about the fact that the meeting is currently over, despite this being simple past tense. This point comes across just fine whether or not you say something like has already ended.

Answer 2

なっている is continuous, so it means “has become” whereas なった is in the past tense, so it means “became.” For example, 医者になっている (“I have become a doctor”) versus 医者になった (“I became a doctor”). The nuance of these two is similar in both Japanese and English. The first is continuous, implying that one is still currently a doctor, while the second is more ambiguous; it could be that one became a doctor and quit.

Answer 3

Lets start by breaking down なっている なる(dictionary form) → なって(てform) → なっている(ているform)

The ている is used to describe an action in progress or a past even connected with the present. So basically, なっている is describing something that will become and that thing is either related to the past and is connected with the present or the action of becoming is in progress.

My hair got longer. かみがながくなっています。

On the other hand, なった is the past short form of なる. So it means it became and it is not describing an action that is related to the present or is continuous. It's something that happened in the past.