I was wondering, what does the よう form of ある even mean? Does あろう act as volition of the object being spoken about? For example... if someone says 雨が降るでしょう(であろう)... is it the same as "It WILL rain" in that volition is being applied to the object being spoken about?

I'm not looking for ties to English, it's just a lucky example.

No matter how many times someone tries to explain でしょう to me it doesn't make sense... I've been trying to think of it as "It is my guess that"... but it doesn't work in some cases...

I still figure that there are two options:

  1. The kinda iffy option based in someone telling me that the よう form is comprised of a "guess particle"... "う":

    The よう form highlights your guess about the future... so saying 行こう means that you are placing your bets so to speak that "going" is what most probably will eventuate.

  2. The way I think makes more sense:

    よう form truly does equate to our "will" and thereby is used in the same sense as "I will go"”行こう" and "it will rain""雨が降るでしょう"

  • 2
    That's an interesting idea, relating it to modal will. Since English doesn't have a future tense, we often end up using modals (literally expressing uncertainty) to talk about the future, and to express volition as well (see Language Log for a summary of will in English). In any case, you might want to read the note at the bottom of 大辞林's definition for だろう (the part starting with 現代語では・・・)
    – user1478
    Nov 17, 2013 at 3:04
  • That's all very interesting to read... but I haven't found ANYTHING to do with this "推量の助動詞「う」" that it's talking about which I feel is the key to the problem.
    – Nathan
    Nov 17, 2013 at 4:33
  • 3
    Here's the entry for 助動詞「う」 in 大辞泉, which comes from the historical 助動詞「む」. That's the bit that だろう has in common with 〜(よ)う etymologically speaking, though I think it's really best to treat だろう/であろう and でしょう as separate words in modern Japanese. They aren't really volitional forms of だ or です, and I would argue they aren't really forms of だ or です at all (you can say 行くだろう but not *行くだ, for example).
    – user1478
    Nov 17, 2013 at 4:42
  • (Sorry for leaving all the comments instead of an answer. I think you can trace the meaning of both だろう and 〜(よ)う back to む and show how it took two different paths and relate it all somehow, but I'm still just learning and I don't feel confident enough to explain all that historical stuff myself.)
    – user1478
    Nov 17, 2013 at 4:45
  • No don't apologise this is fantastic! So basically it is like a mixture of my two above hypothesis perhaps. It shows volition in a roundabout way by showing where you place your guess regarding thefuture I mean when we say "I will go to the shops" it is a strong emphasis of us saying what is going to happen.. however since it has not happened yet... it is still a guess.. however because our desires are involved it is a strong guess. Same with "it will rain" being like saying that the rain's "will" is to fall. The connotation is that regardless of what happens, it's "will" will be fulfilled.
    – Nathan
    Nov 17, 2013 at 4:49

2 Answers 2


As someone who has never studied Japanese as a foreign language, I am often amazed at how often I hear Japanese learners use the word "volitional" because they seem to use it even where volition appears least relevant by Japanese standards. Whether it rains or not has nothing to do with anyone's volition, for it is a natural phenomenon.


で: the 連用形 of the concluding auxiliary verb だ

あろ: the 未然形 of the verb ある

う: the inferring auxiliary verb

でしょう is the polite form of であろう. Both mean the exact same thing in the context 雨が降るでしょう(であろう)= "It is mostly likely to rain.".

Regarding でしょう that you feel does not make sense at times, you may need to give some examples for us to discuss it. It is indeed used in different situations.

  • Is it possible for the 未然形(お) + う form to represent an inference in any other verb than ある in modern Japanese? For instance, 「書こう」や「食べよう」など. Or is this just a だろう・でしょう thing? If it's possible for any verb to represent an inference, can you give some examples?
    – rintaun
    Nov 18, 2013 at 15:35

I think that 雨が降るでしょう means more of a "it kinda probably would rain". Yes, weather forecasts say that, but Japanese people aren't noted for being particularly direct.

Similarly, something like 私が猫だったら、ビデオをたくさん作るでしょう (pardon my possibly bad Japanese) would mean "if I were a cat, I would probably make lots of videos". It doesn't mean "if I were a cat, I would make lots of videos"; the でしょう is only there because you don't want to sound overly direct when making speculations about hypothetical situtations.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .