Is 戦う related to 叩く?


Are 戦う{たたかう} and 叩く{たたく} related?

They have a similar pronunciation, and their meanings are close enough (fight
vs. hit) that I think they could stem from the same origin.

My theory is that 戦う started off as たたき合う but then the sound blended into
たたかう, becoming its own word and branching off into its current meanings. But I
have basically no knowledge of etymology at all so I am probably way off the
mark.

Are they related? And if so, how?




### 叩く and 戦う

Etymologically, Shogakukan's 国語【こくご】大辞典【だいじてん】 and
[大辞林【だいじりん】](http://www.weblio.jp/content/%E6%88%A6%E3%81%86) list just the ふ
auxiliary derivation. Meanwhile,
[大辞泉【だいじせん】](https://kotobank.jp/word/%E6%88%A6%E3%81%86-560684) lists both
the ふ auxiliary and the 合う possibility as derivations.

Given the not-uncommon pattern of deriving iterative / repetitive /
continuative verbs by appending ふ to the 未然形【みぜんけい】, and given the appropriate
semantics here (叩く "to hit something" ⇒ 戦う "to be hitting something
(repeatedly)" → i.e., "to fight"), the ふ auxiliary derivation seems more
likely.

### Broader patterns

Other verb pairs with similar derivations include:

  * 病む【やむ】 "to get sick" ⇒ 病まう【やまう】 "to be sick" (obsolete)
  * 語る【かたる】 "to talk, to tell" ⇒ 語らう【かたらう】 "to be talking, to be telling"
  * 住む【すむ】 "to settle (in a place)" ⇒ 住まう【すまう】 "to be settled", i.e. "to be living in a place"

The original ふ often just became う, but in many other cases, this underwent a
further shift into the 已然形【いぜんけい】, changing from ふ to へる to える. This expands
the list of pairs to include examples such as:

  * 押す【おす】 "to push, to press" ⇒ 押える【おさえる】 "to be pushing, to be pressing" → also "to repress, to hold down"
  * 取る【とる】 "to take" ⇒ 捕らえる【とらえる】 "to be taking, to take and hold", i.e. "to capture"
  * 踏む【ふむ】 "to step, to tread" ⇒ 踏まえる【ふまえる】 "to be stepping", i.e. "to be of a position, to have taken a stance"

The key semantic shift is that the bare verb expresses a momentary action or
change of state, while the verb + ふ expresses an ongoing or repeated action or
state.




### 叩く and 戦う

Etymologically, Shogakukan's 国語【こくご】大辞典【だいじてん】 and
[大辞林【だいじりん】](http://www.weblio.jp/content/%E6%88%A6%E3%81%86) list just the ふ
auxiliary derivation. Meanwhile,
[大辞泉【だいじせん】](https://kotobank.jp/word/%E6%88%A6%E3%81%86-560684) lists both
the ふ auxiliary and the 合う possibility as derivations.

Given the not-uncommon pattern of deriving iterative / repetitive /
continuative verbs by appending ふ to the 未然形【みぜんけい】, and given the appropriate
semantics here (叩く "to hit something" ⇒ 戦う "to be hitting something
(repeatedly)" → i.e., "to fight"), the ふ auxiliary derivation seems more
likely.

### Broader patterns

Other verb pairs with similar derivations include:

  * 病む【やむ】 "to get sick" ⇒ 病まう【やまう】 "to be sick" (obsolete)
  * 語る【かたる】 "to talk, to tell" ⇒ 語らう【かたらう】 "to be talking, to be telling"
  * 住む【すむ】 "to settle (in a place)" ⇒ 住まう【すまう】 "to be settled", i.e. "to be living in a place"

The original ふ often just became う, but in many other cases, this underwent a
further shift into the 已然形【いぜんけい】, changing from ふ to へる to える. This expands
the list of pairs to include examples such as:

  * 押す【おす】 "to push, to press" ⇒ 押える【おさえる】 "to be pushing, to be pressing" → also "to repress, to hold down"
  * 取る【とる】 "to take" ⇒ 捕らえる【とらえる】 "to be taking, to take and hold", i.e. "to capture"
  * 踏む【ふむ】 "to step, to tread" ⇒ 踏まえる【ふまえる】 "to be stepping", i.e. "to be of a position, to have taken a stance"

The key semantic shift is that the bare verb expresses a momentary action or
change of state, while the verb + ふ expresses an ongoing or repeated action or
state.

