translation - よかろう - What does it mean? Where does it come from?

This is another question that's come from a 昔話。

We have the following section:

大きい箱と小さい箱がありますが、どちらがいいですか。
どちらも結構じゃが、どうしてもと言うのなら、小さいほうでよかろう。

I'm having trouble with the second sentence. My translation is:

• どちらも結構じゃが - Either one is fine. - Here, I think じゃ is a contraction of では and has the same effect as using です.



• どうしてもと言うのなら - If you say I must - の seems like the explanation modality to me.


• 小さいほうでよかろう - The little one would be better. - I'm guessing that ほうで is a less emphatic version of ほうが. Just going on context for よかろう meaning good.

What I'm really interested in is where よかろう came from. At first glance, it seemed like some crazy old volitional form (行こう!）, but It seems kind of ridiculous for there to be a volitional form of an adjective. It really seems like it could be the adjectival form of だろう. (I read something that sounded similar to this that was the adjectival form of だろう, but cannot find the link again.)

• What does よかろう mean?


• Is it equivalent to いいだろう?


• Is this just one of those old fashioned feeling Japanese grammatical forms?


• Is there a case where I could actually put this to use (other than reading 昔話)?

Answer

よかろう is not so different from いいだろう. The crucial part is the same. And your concern about having a volitional form for an adjective is right, but is only half way. If you worry about the volitional form, then why do you not worry about the plain ending form, past form, etc. of adjectives? If you decompose the adjectives, you can observe that all these endings are actually verb endings. They merely look like adjective endings because they are contracted.

よかろう < yoku ar-ou
(possibility form ou attached to the verb ar)
'it is probably good'

い/よいだろう < i/yoi de ar-ou
(possibility form ou attached to the verb ar)
'it is probably good'

い/よいでしょう < i/yoi des-you

(possibility form (y)ou attached to the verb des)
'it is probably good' (polite)

よかろう is slightly old fashioned, but is still in use when you either want to be formal or authoritative.

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じゃ in じゃが is not では but is the same as だ, which historically comes from である.