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Why do the verbs 為る【する】 and 為す【なす】 ("to do") use the same kanji as 為【ため】 ("because of", "for the sake of", etc.)? I'm not seeing any obvious connection between the meanings of する・なす and ため that would explain why they use the same kanji, and they don't appear to be etymologically related either.

(Yes, I'm aware that nobody writes する or なす with those kanji, but that's how it's listed in dictionaries, so I figure it's worth asking anyway.)

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The simple reason is that 為 already had those meanings in Chinese. – Zhen Lin May 15 '14 at 7:34

Conventions: I will use 漢字 to represent Chinese words, and かな or [振り仮名]{ふりがな} to represent Japanese words.

なす/なる and “to make”

為 is related to (and might have been the same as) 偽, “to forge”. Both なす and なる happens to translate to “to make” in Chinese.

When you make “an object” you produce it. Sometimes the active and passive distinction in Chinese is not so clear, e.g.

[書下]{かきくだし}し:氷{こおり}は、水{みず} 之{これ}を為して{なして}、而も{しかも}水{みず}より寒し{さむし}
Also: 氷{こおり}は、水{みず} 之{これ}と為りて{なりて}、而も{しかも}水{みず}より寒し{さむし}
Translation: “water makes ice” or “water turns into ice”

The difference is not clear.

なす/なる and “to do”

When you make “an action” you do it. When you try to do something, you 為す{なす}. When something is done, it 成る{なる}. 為 is the process while 成 is the result. It's similar to the difference between “look” and “see”. This distinction does not exist in Japanese. なす usually implies なる.

Translation: where there is a will, there is a way

“To do” and “purpose/reason”

In Chinese, there is no question word meaning “why”. “Why” is expressed as “what to do” (何為 or 為何). Coincidentally, Japanese sometimes says “what to do” to express “why”, too, e.g. ~なんすれぞ(archaic) なにしに and どうして.


why don't you leave here?
What did you come here for?

ため and “purpose/reason”

I think ため means “benefit”.

~ために、~する means to do something so that it helps something else. The grammar is straightforward, too. When you say “~を~にする” the result is “~が~になる”.


ため, する and 為 share the same meaning “for”. する, なす, なる and 為 share the same meaning “to do”/“to make”

All the four words (ため, する, なす and なる) end up with the same kanji representation 為.

A little more

It's not uncommon to see words meaning “be made” develop into copulas. 為 is also a copula in Chinese. In this case, it's read as たり, which is a contraction of とあり.

Translation: someone who is a servant

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Yang, this part isn't quite right: When you make “an action” you do it. When you try to do something, you 為す{なす}. When something is done, it 成る{なる}. 為 is the process while 成 is the result. It's similar to the difference between “look” and “see”. This distinction does not exist in Japanese. なす usually implies なる. "Look" implies intent, while "see" doesn't. This distinction indeed does not exist in Japanese. However, the passive-intransitive / active-transitive distinction most certainly does exist in Japanese, as evidenced by pairs like なす・なる, 貸す・借る (modern 借りる), 溶かす・溶ける, 増やす・増える, etc. – Eiríkr Útlendi May 15 '14 at 19:06
なる(為る・成る etc) is not necessarily the result of なす(為す・成す etc). Something can "become" all on its own, without any external agent. If something is done, specifically by someone, it's more common in Japanese to use the passive 為される. なる itself does not have the same meaning as "to do". That said, 為 in Chinese does appear to have the same meaning as both "to do" and "to become", depending on context, probably due to the Chinese-specific phenomenon you describe where passive-intransitive and active-transitive are not always distinct. But note that, in Japanese, these are distinct. – Eiríkr Útlendi May 15 '14 at 19:14
Regarding the character derivation, the EN Wiktionary entry agrees with what I recall reading some time back, that 為 was originally a pictograph of an elephant, later used for "to do, to become" for its phonetic value. Meanwhile, 偽 is a clearly a compound, adding the "person" radical to the 為 character. As such, I really don't think that 為 and 偽 were ever the same. Perhaps you mean instead that both characters might once have had the same meaning, "to forge"? – Eiríkr Útlendi May 15 '14 at 19:23

For that, you might have to ask on a Chinese etymology site -- both meanings, "to do" and "because of", can apparently be ascribed to the underlying Chinese term 為: with the reading wéi for "to do", and the reading wèi for "because of". See the entries on MDBG and Mandarin Tools.

In most cases of Chinese characters used in Japanese, the various kun'yomi for the kanji weren't just picked willy nilly. In fact, the "kun" part of "kun'yomi" indicates the meaning of the term in Japanese (i.e., the native Japanese word(s) that matched the meaning of the kanji), while the "on" part of "on'yomi" referred to the sound of the term as read in Chinese (i.e., the sound of the foreign word that the kanji belonged to). If a single kanji had multiple meanings, or a broad meaning that might have matched multiple native Japanese words, you wind up with cases like 為 that have multiple kun'yomi. If a single kanji was imported into Japanese from multiple different Chinese dialects, or at multiple different points in Chinese history, you wind up with cases like 生 that have multiple on'yomi (sei, shō).

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