A question about ~はしない

Question

I do understand what it means, but I want to know if it's mostly used from 1st person perspective because in many examples that's how it translated. "I will never/There is no way I..."<-That is how I see lot of times.

Is it used more when I express a strong desire or is it alright to say when talking about others?

For example, I had these lines in a manga (note, this is the speaker's internal thoughts. He is thinking 'what if Yosuke fails? Then what? 'That kid' comes to the speaker's mind who was almost in the same league (in terms of fighting skills) as Yosuke, but now considers that 'the kid' won't be of help, if Yosuke won't prevail). So the speaker is thinking this:

"あんな小僧に何ができる。洋介の予備にもなりはしない。”

Is the speaker saying: "What could that kid do? (or be able to do?) There's no way I can have him as a reserve for Yosuke.

Here, is it stressed that the speaker does not want to have to make "the kid" a spare/reserve? (There's no way I can even have him as a reserve), or is it more like "That kid can't even be(become) a reserve for Yosuke."

I am asking if there is emphasis from the speaker, like "It's out of the question (for me), I will not resort to make 'that kid' a backup plan".

Hope I explained well enough.

Answer 1

「あんな小僧{こぞう}に何{なに}ができる。洋介{ようすけ}の予備{よび}にもなりはしない。」

The unmentioned subject of the second sentence is none other than 「あの小僧」.

The main verb of that sentence is 「なる」 ("to become") in the emphasized negative form 「なりはしない」 ("will never become").　Who could or could not become a reserve for Yosuke here? It would logically be あの小僧.

If the unmentioned subject of that sentence were the speaker, 「なる」 could never be used because it would make no sense as the speaker is not the one who might become the reserve for Yosuke. Instead, the verb part would need to be changed to something like 「～～にもしやしない」 using the verb 「（～～を～～に）する」 (""to make ~~ become ~~).

It seems you are over-analyzing the sentence this time. Perhaps the hidden 「する」 in 「はしない」 got you somehow, but as I said above, the main verb is 「なる」 and that is what should determine who the action-taker is.

Answer 2

Disclaimer: I am still pretty new to Japanese myself, so I may be completely off-base here.. You may want to wait for some other folks to weigh in before deciding whether this answer is good or not.

First of all, はしない literally translates to "(regarding that previously stated thing) (somebody) won't do it". Since しない is the simple negative of する (to do), it conveys the sense of "won't do", as opposed to "can't do", so I think your potential translation of "That kid can't even be a reserve for Yosuke" doesn't actually work (since there's no sense of "can't" conveyed by しない).

Since the subject isn't actually specified, it seems to me it might be more appropriate to translate はしない itself as simply "it won't happen", but it's also (I believe) usually a somewhat emphatic statement, which might make it more like "it's not gonna happen!".

As for who the subject of the action is, I think in some cases it may depend a bit on context (i.e. who would be expected to make that happen if it was going to happen), but if we couple this with the fact that Japanese speakers are usually much more reticent than English speakers to put motivations/feelings into other people's mouths (e.g. instead of saying "Fred is sad", a Japanese speaker would say "Fred appears to be sad" or "I believe that Fred is sad"), in general I suspect that emphatically saying that somebody else definitely will or won't do something would be a bit presumptuous, and probably not something Japanese speakers would be inclined to do. Given this, it seems likely that, unless it's explicitly stated otherwise, such an expression would normally be assumed to be referring to the speaker's intentions (since they're the only person they can claim to know definitively won't do something).

I'm not a native speaker, though, and don't have a whole lot of experience with Japanese interactions in general, so more experienced people, please feel free to tell me if I'm wrong on all of this...