The example my book gives for an ungrammatical usage is "山田さんがくれば、いっしょに大阪に行きませんか?" I recognize that such things are the standard, but nowhere in any of my research is it indicated why that's the case, nor does it explain why sentences like "高ければ、買わない方がいいですよ。" are considered grammatical. Can anyone clarify this(as well as what falls under an ungrammatical will, wish, order or request, in this context)?

  • You're asking why it's ungrammatical, but isn't your title the exact rule which explains why? Are you asking why that rule exists?
    – dainichi
    Jun 20, 2013 at 3:42
  • Specifically, what makes it ungrammatical? Nothing I've come across explains why it's the case or gives any clear examples illustrating the difference between an ungrammatical and grammatical usage of the two Jun 20, 2013 at 3:46
  • +1 because I have wondered myself why these complex use cases arise for the varying similar ways to say "if." The only explanation I ever got was a declaration that this is how it is with no suggestion as to why.
    – ssb
    Jun 20, 2013 at 6:58
  • This is unsourced and people would eat me alive if I posted it as an answer (hence the comment). My understanding is that ~ば and ~と are for "If" statements where the conclusion follows naturally from the premise. So in the first example, nothing related to Yamada-san coming would suggest that two other people should go to Osaka, but something being expensive could naturally suggest that it shouldn't be bought. 作ると、人が集めます (If you build it, they will come) would be fine, while 作れば、阪神が優勝する probably isn't.
    – jmac
    Jun 20, 2013 at 7:11
  • Related: japanese.stackexchange.com/q/393/78
    – istrasci
    Jun 20, 2013 at 15:30

1 Answer 1


I think it has simply to do with the kind of nuance that is conveyed when a particular "if"-construction is used.

と suggests that whatever follows needs to be a natural, unavoidable consequence and a wish/will/order/request is not a natural consequence.

If Mrs. Yamada can come, then her husband won't be able to come. (Because one of the two has to watch the kids.)

I always think of ~れば and ~たら as a pair with ~れば being the non-past tense version and ~たら being a past tense version.

If it turns out that Mrs. Yamada can come, should we go to Osaka? (...to avoid having to meet her.)

~れば suggests that knowing whether the "if" part will be true is enough to follow through on the "then" part.

~たら suggest that once the "if" part has already occurred, one should do the "then" part.

If/when Mrs. Yamada has been able to make it here, why don't we all go together to Osaka?

So, strictly speaking, I don't think the wish/will/order/request with ~れば is ungrammatical, but the nuance is not the one you expect when you translate it as a simple if-then construction into English.

なら is independent of whether the "if" part has already occurred or hasn't yet occurred, so

If Mrs. Yamada can come, should we go together to Osaka?

is probably open for either interpretation (i.e. go all together or go to avoid her), but going all together is probably the more likely interpretation.

  • Hmm, alright, I can buy that. For clarification, though, what would fall under an ungrammatical will, wish, order or request with the two discussed ways to express a condition? Jun 21, 2013 at 3:04

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