I was doing some reading, and I read that while the volitional form can be
explained as coming from the 未然形 for う-verbs, it cannot be explained for
る-verbs. (I'm sure I should be using better terminology here, like 五段, but the
correct words escape me.) Is this true? Can the usage of よ in the volitional
form not be explained?
CC BY-SA 3.0
2014-09-22T05:21:06.913
18766
2014-09-23T01:05:32.227
question
history volitional-form
Origins of the Volitional Form
>
> 〔一段活用・二段活用の動詞に推量の助動詞「む」を伴ったもの，例えば，「見む」「受けむ」などは，中世末期までに「みう」「うけう」から「みょう」「うきょう」の形に変‌​化していたが，そこから，動詞未然形「み」「うけ」と助動詞「よう」とが分かれて，助動詞「よう」が生ずるに至った。現代語のように，五段活用の動詞には「う」が，その他の‌​活用の動詞には「よう」が付くというように，接続のしかたを補い合うような用法が一般的になるのは近世江戸語以降のことである〕  
>  ― [大辞林 entry for
> よう](http://kotobank.jp/word/%E3%82%88%E3%81%86?dic=daijirin)
>
> Combinations of monograde (一段) and bigrade (二段) verbs with the conjecture
> auxiliary _-mu_ , for example _mi-mu_ and _uke-mu_ , had transformed from
> _mi-u_ and _uke-u_ to _m-you_ and _uk-you_ by the end of the Middle Ages;
> however, at that point, they were reanalyzed as the imperfective forms (未然形)
> _mi-_ and _uke-_ plus the auxiliary _-you_ ― and thus, the auxiliary _-you_
> was born into existence. The notion of complementary auxiliaries, such as in
> modern Japanese, where _-u_ attaches to quintigrade verbs and _-you_
> attaches to other verb classes, did not become predominant until the modern
> Edo dialect. (Translation mine.)

Whether 大辞林 is to be believed or not, I'm not sure, but it sounds quite
plausible to me. _Classical Japanese: A Grammar_ by Haruo Shirane gives a
similar explanation:

> "In the Heian period, _mu_ also appeared as the nasalized sound-change _n_.
> Beginning in the Kamakura period, this _n_ changed to _u_ (う), which is how
> it appears in modern Japanese. Thus, _ika-mu_ (行{い}か **む** , I will go)
> becomes _ika-n_ (行{い}か **ん** ) and then ikō (行{い}か **う** ). This _u_ also
> combined with the preceding verb stem to become _yō_ (よう), as in modern
> Japanese _tabeyō_ (たべよう, let's eat)."  
>  ― Shirane, H. (2005). _Classical Japanese: A Grammar_ (p. 99). New York,
> NY: Columbia University Press.
CC BY-SA 3.0
2014-09-23T01:05:32.227
18772
2014-09-23T01:05:32.227
3097
18766
answer