る/base verb and た are just a another version of ている in a relative clause?

Question

https://japanese.stackexchange.com/a/3362/65948 https://japanese.stackexchange.com/a/3364/65948 https://japanese.stackexchange.com/a/43875/65948

And many others say that it doesn’t matter what tense is modifying a noun, ている and た mean the same thing if 1)they are modifying a noun and 2)the verb itself expresses a state and not the English -ing.

That’s all fine and well until I saw this post: https://japanese.stackexchange.com/a/73683/65948 I’ve never seen a dictionary form being changeable with the た　form in a relative clause. This wrecked my existing knowledge that only た　and ている can be changed without their meanings changing. I was so confused about it.

That’s when I saw these posts: https://japanese.stackexchange.com/a/14553/65948 https://japanese.stackexchange.com/a/14273/6594 It all makes sense now, る　ている　た　means the exact same thing. It all basically boils down to this:

た=ている=る　they all have the same meaning as ている and た and る　are just a disguised version of it

But the two rules that only this can happen is

1. it has to be in a relative clause but more importantly
2. the verb has too be a stative verb to begin with.

If these two are fulfilled, then it doesn’t matter what you choose cause they all mean the same thing. At the end of the day they only have slight difference that being:

1. base verb is more likely to be seen in formal/polite places like in a story or newspaper etc and thus have a more polite feeling to it and because it’s uses the base form of the verb, it pulls you into the time period that happens, like you’re actually there of when that thing happens, making it more “real time action” https://japanese.stackexchange.com/a/43622/65948 And because of this link, this means that this is the historical present, for so long I’ve been so stumped about it until this came and clears everything for me. Your both using the more polite version of ている (る/base verb) and also you’re using historical present at the same time. A double combo that I didn’t see coming.

2. ている　being used in colloquial/day to day places so that’s why the base verb is preferred in formal scenarios. So you should use it with friends but not in a speech or something like that. It also focuses on more of the state itself than the verb being done

3. た can be used in formal or informal scenarios but it doesn’t have the same kind of pulling that る/base verb has, it just tells you about it and doesn’t give you the “real time action” that it has. And this usually has more of a nuance that the verb has been done instead of saying what the state is like right now.

For a demonstration, I’m going to take this "太ってる猫" vs "太った猫"

太ってる猫=太った猫=太る猫

They all mean the exact same grammatically. Cause at the end of the day, た　and る/base verb are all just a different version of ている with slight nuance. They are all interchangeable.

But that just leaves me with this question, is this answer credible? https://japanese.stackexchange.com/a/11976/65948

By credible I mean his method of determining when a verb can be interchangeable with た　and ている cause there are two explanation that he gave and I’m not quite sure that he knows what he’s talking about. The first one is:

shouldn’t かぶる be in its causative form like one of the comments says

And number two:

Shouldn’t this be 食べられた? 食べたケーキ means “A cake that ate(something)” like literally a sentient cake that ate something? Even if you don’t thing that’s the case then the it still wouldn’t make sense cause the cake still isn’t getting eaten by someone cause 食べた is just ate and not got eaten, 食べられたケーキ　means “a cake that got eaten (by someone)” so I really hope someone actually comes out and clears it up cause I still have no idea how or when a verb can be interchangeable with た　and ている. My guess is that it must have to do with the verb being stative in the first place or not.

And also regarding his explanation on the dictionary form does in a relative clause, he says it usually takes the future reading and habitual reading but doesn’t say anything about it being used in formal scenarios, like this post says, https://japanese.stackexchange.com/a/14553/65948

So I might need someone to fact check on it, or maybe both can be accepted cause at the end of the day context matters the most.

Answer 1

I originally didn't want to answer this because it's a bit long and I don't feel confident to provide a complete answer, but no one else is so I'll provide a partial one to the best of my abilities.

Firstly, the common similarity between “〜ている” and “〜た”　has nothing to do with relative clauses and exists everywhere. The same exists in English too. “I have eaten.” and “I ate.” have fairly interchangeable meaning, but one focuses on the result in the now, and the other on the action in the past that caused said result. “〜ている” at it's core meaning indicates a monotonous span of time rather a point. This is frequently the result of the verb, such as say in “温まっている” but may also be, if the verb be monotonous in it's own right such as “食べる” mark the currently ongoing action such that “食べている” can both mean “has eaten" and “is eating” depending on context because “eating” unlike warming up is a monotonous action without a clear endpoint where something is transformed. Outside of relative clauses “太った” means “I got fat.” and “太っている” means “I have gotten fat.” or “I am fat.”, even in English, these two have nigh-identical meaning.

Now, as for relative clauses. There are two important things to unpack: first is that Japanese relative clauses have relative tense, not absolute tense like in English. Their tense is relative to the main clause they're embedded in, as such, in Japanese we say “食べている人を見た。” to mean “I saw someone who was eating.”, namely, at the time of seeing, that person was currently eating, so the past form is not used. If it were, it meant one saw someone who was already done eating, and had eaten in the past relative to seeing, as in “I saw someone who was eating before I saw him.”, if you will. This also means that past forms in relative clauses can be used for a future event, as in “食べたあと寝るつもりだ。” as in “I plan to go to bed after I have eaten.”, even though the “食べた” lies in the future relative to speaking, it is relative in the past to the planned time of going to bed, so the past tense is used.

The second thing to unpack with regards to relative clauses is that indeed for many verbs, the plain form seems to be interchangeable with the “〜ている” form. I can't give a very confident answer to what subset this exactly is. It seems to be pretty much exactly the subset that uses the “〜ている”　form to mark a resultant state, but I'm not entirely sure of that either. As an example I can use “それを知る人と話していた。” to mean “I was talking to someone who knew that.”. This is essentially interchangeable with “知っている” yes and this applies only to relative clauses. “それを知る” does not mean “I know this.” but “I will learn of this.” and we must outside of a relative clause use “それを知っている。” or “それを知った。” which means “I have learned of this.” As far as I know “パンを食べる人と話していた。” does not mean “I was talking to someone who was eating bread.”, but I might be wrong about this. Again, I'm providing an incomplete answer here simply because no one else is.