The uses & etymology of で

Question

In Japanese, the particle で seems to have multiple uses:

1. Instrumental: 車{くるま}で大阪{おおさか}に行{い}った。 "I went to Osaka by car."
2. Locative: 図書館{としょかん}で数学{すうがく}を勉強{べんきょう}している。 "I'm studying math in the library."
3. て-form of copula: 水{みず}はきれいで静{しず}かだ。 "The water is pretty and calm."
4. て-form of copula (sentence conjunction): 彼{かれ}は来{く}るので、大丈夫{だいじょうぶ}だ。 "He's coming, so it'll be fine."
5. 連用形{れんようけい} of copula: そうではない。 "That's not how it is."

(It may be possible to analyze #4 as a 連用形, in the 中止形{ちゅうしけい} sense, but I don't think that's what is in modern usage, since there is an implication of temporal order.)

What is the origin of these uses? Do all these でs historically come from one thing?

(I've heard that "で came from にて", but that doesn't really explain much for me in terms of how all these forms came about and if they are really all from the same original thing.)

Answer 1

What is the origin of these uses?

1. Instrumental: contraction of case particle -ni and particle -te. In many cases (*), you can interpret this as ni + verb + -te. In your example, it could be 車に乗って大阪に行った.
2. Locative: contraction of case particle -ni and particle -te. In many (*) cases, you can interpret this ni + verb + -te. In your example, it would be 図書館「に来て」数学を勉強している.
3. Te-form of copula: contraction of 連用形 of copula -nari (-ni) + the particle -te. More precisely, -nari itself is a contraction case particle -ni + verb ar-, so while not direct, the etymology is essentially the same as #1 and #2.
4. Reason: This is not the te-form of the copula. Rather, it expresses reason. It is a contraction of case particle -ni and particle -te.
5. 連用形 of copula: Same as #3.

Note (*): I have not done a survey of this, nor am I aware of any such studies. So I will refrain from saying 'always'. But it is a tendancy that I have noted numerous times over the years.

Do all these でs historically come from one thing?

You would be safe to split them into two groups: (#1, #2, #4) and (#3 and #5). Though as I wrote, an argument could be made that they are all ultimately of the same etymology.

There is another de that you are missing. As in a conversation a person can say "de? (dou natta? nani ga atta?)" to help continue the topic. This is an abbreviation of "soko de" or "sore de".

There is also de found in various Kansai dialects. "iku de", "koute kita de". This is thought to be a variation of "ze" (~zo).

Both of these would be in their own etymology groups as well.