Does てから any retain "subjective reason for action" meaning from から?

Question

My understanding of how から, ので, and て differ from each other when linking clauses:

• から links a subjective reason for someone's action
• ので links an objective reason for someone's action
• て can indicate natural cause and effect relationships (in a sense, it shows causality that's even more "objective" than ので).

But what about てから? Supposedly, てから disambiguates actions which could be performed simultaneously or in sequence in て-sentences:

歯を磨いてテレビを見た。

I brushed my teeth and watched TV. (Ambiguous whether this happened in sequence or at the same time).

歯を磨いてからテレビを見た。

After brushing my teeth, I watched TV. (てから forces the interpretation to be sequential).

But in this last example, does てから retain any of that "subjective reason for action" quality, like から does? For example, is the speaker here implying that finishing brushing his teeth played some subjective motivational role in making him want to watch TV?

If so, does てので exist as a way to show a sequence of actions in which the former acts as an "objective" reason for the latter action?

Answer 1

No, it doesn’t, just like ８時からテレビを見た has no subjective sense.

〜ので is the conjunctive form of 〜んです, which is actually a contracted form of 〜のです. It connects to a plain form, not a て-form. (〜てんで would be an informal contracted form of 〜ているので. It’s a different thing.)

Answer 2

ので connects to a plain form, as an alternative to putting the verb in て form. Alternately analyzed: this で is just the て form of the copula, and the の is nominalizing. Thus, using ので, the verb is used attributively to describe a placeholder pronoun, and then it's made back into a verb by adding the copula, and put in て form again.

Just like ending a sentence with のだ・んだ, this tends to have an "explanatory" function. Wiktionary's example is

今日は日曜日なので、学校に行きません。

(Wiktionary translation) Because it's Sunday, I won't go to school.

(My gloss) Today [topic] Sunday -is -it being, school -towards go-[polite]-[negative].

The "because" sense comes from the fact that we are emphasizing a state of being: 今日は日曜日な is just "Today is Sunday", の gives us "the fact that today is Sunday", and で makes it "it being the case that today is Sunday".

Wiktionary lists ので as a "polite form" of から, which I suppose it effectively is - because it's a grammatical circumlocution that ends up having the same effective meaning. から quite directly means "because" or "since" - or more broadly, "following". This is after all the same から as in これからも "from now [lit. here] on". (から can also follow multiple forms of speech, whereas ので needs to follow a verb so that の can nominalize it.)

I do understand ので (and から, when used connectively) to connote some kind of logical causation or at least sequencing, but it doesn't have to be about reasoning. Connecting simply with て suggests to me that the two actions are logically part of a larger whole - so から is needed after the て form for requests (since the thing you're requesting isn't directly connected to the current action; you're just asking for something to happen after that).