Understanding て＋助詞


Frequently, て (te form) is used to indicate simultaneous, sequential, or
causal relationships between the part of the sentence that comes before and
the part of the sentence that comes after.

Ordinarily, what follows て is a clause that could otherwise stand alone. For
example, a full sentence, just a verb or just an adjective. Some standard
patterns are below. Everything after the ＋ in each of these cases could
function as a standalone idea.

～て＋くれる

～て＋ください

～て＋あげる

～て＋もらう

～て＋ある

～て＋いる

～て＋いく

～て＋くる

～て＋みる

～て＋おく

～て＋しまう

～て＋ほしい

In addition to these standard patterns, you of course have the flexibility to
create your own sentence combinations. For example:

> この人は綺麗で、有名だ。
>
> 安くなくて、買わなかった。

Again, what is listed after て・で is a standalone sentence.

However, what seems to break this pattern are constructions like the following
three.

～て＋から

～て＋も

～て＋は＋いけない

What exactly is going on here? Is the て form in these patterns somehow being
used as a way to nominalize the first part of the sentence in the same way as
の or こと might?

For example, could I technically make the following changes without a
difference in meaning, even if not a very natural/standard phrasing? I'm
mostly trying to understand exactly what て form means here, and if my
suspicions about て being a very specific-use clause nominalizer are correct.

  * スパーに行ってから、家に帰った。 → スパーに行ったのから、家に帰った。

  * 一緒に映画を見てもいい？ → 一緒に映画を見るのもいい？

  * 話してはいけない → 話すのはいけない

In all these examples, what comes after て is **not** a standalone sentence.




I am not sure this will be an answer to your question, but I couldn't fit all
my thoughts into a comment.

First, in regard the examples you asked about:

> For example, could I technically make the following changes without a
> difference in meaning, even if not a very natural/standard phrasing?

In short, no.

  * `スパーに行ったのから` is borderline ungrammatical and looks like you were trying to give a reason with `スパーに行ったんだから`. (changing this to `スパーに行った事から` does not make it viable)
  * `一緒に映画を見るのもいい`is weird as a question, and the nuances are different from `見てもいい`. `一緒に映画を見るのもいい` sounds like a suggestion to me, in the vein of "watching a movie together would be fun too".
  * `話すのはいけない` this gets the closest to the original meaning, but is certainly less natural than `話してはいけない`, at least for directly telling people what they can or can't do. A native speaker may have to weigh in on differences in nuance. 

Speaking really broadly, I think that the て form (テ形) is just not as
systematic as you or I might like it to be. The relationship between whatever
comes after the テ形 verb and what came before it _depends on what comes after
it_. I deal with this by thinking of `ておく`, `てほしい`, etc. each as their own
construction.

Edit: please also see a very related answer
[here](https://japanese.stackexchange.com/a/18965/7705).

**If that's all you needed, feel free to stop reading now.** If you remain
unconvinced, I have addressed some of your supporting examples below.

Your wrote:

> Ordinarily, what follows て is a clause that could otherwise stand alone.

but I'm not sure the example words you gave actually agree with this
statement. While they can arguably stand alone from a purely syntactic point
of view, I'm not sure this is a useful definition of "stand alone" because
they end up meaning something completely different. For example, with
[おく](https://jisho.org/search/%E3%81%8A%E3%81%8F), its use as an auxiliary
verb (when it comes attached to a テ形 verb) has a totally different meaning
than its use as a standalone verb. Without getting into a debate about how to
delineate words, I am pretty comfortable calling the auxiliary verb `て＋おく` a
different word from the transitive verb`を＋おく`, and this pattern applies to
some degree to all of your examples.

Even when separate clauses follow the テ形 verb, they are typically either a
result of the preceding clause or sequentially come after it. See
[here](https://japanese.stackexchange.com/questions/61372/differentiate-a-
cause-from-a-succession-of-terms-in-a-sentence-
using-%EF%BD%9E%E3%81%8F%E3%81%A6-%E3%81%A7/61377#61377). In your second
sentence example, the second clause (買わなかった) is clearly causally linked to the
first.

