Hi all! This seems like it shouldn’t even be that confusing, I feel like I may be taking crazy pills.
In Genki 2 page 34-35, なら is introduced like so:
A statement of the form “noun A なら predicate X” says that the predicate X applies only to A and is not more generally valid.
It goes on to give the following examples:
チリなら行ったことがありますが、ブラジルは行ったことがありません。I’ve been to Chile, but never to Brazil.
日本語がわかりますか。ひらがなならわかります。Do you understand Japanese? If it is (written) in hiragana, yes.
Now, these - especially the latter - sound like what I’d use the word “only” for in English (“Do you understand Japanese? Only if it is written in Hiragana”), which prompts the question - what is the difference between 「なら」 and 「だけ」?
Looking it up, other places (e.g. tofugu, japanese ammo) describe なら as something seemingly completely different - a form of “if”, emphasizing that it’s a precondition. The very first example from tofugu is fairly clear-cut:
寒いならこれを着てください。 Please put this on if you are cold.
So, that one I get - and there’s doesn’t appear to be a nuance of “only” (i.e. it doesn’t sound like the person is telling me to only put the thing on if I’m cold, and that I otherwise shouldn’t).
What this means is that, while there are guides explaining 「だけ」vs「しか」, or 「なら」vs「たら」, nothing seems to explain 「なら」vs「だけ」 - because if you’re not going by Genki’s definition, there’s no reason to be confused between those two.
So, my questions are:
How come Genki’s definition is so different from the others?
To the question 「日本語がわかりますか」, what is the difference between 「ひらがなならわかります」 and 「ひらがなだけわかります」？
I agree that it’s somewhat confusing how they introduced it (though I haven’t read Genki 2, so I can’t consider any more potential context than what you wrote). Describing it as a way to express a condition makes more sense to me.
To get back to the examples:
This could be interpreted as “If we’re talking about Chile: I’ve been there, but Brazil isn’t a place I’ve been to before”. Granted, their translation sounds more natural but I’m trying to replicate the なら as a condition in the English sentence. It doesn’t mean that Chile is the only place they have ever been to though.
The first one would be (as the translation says) “If it is written in hiragana, I understand [Japanese]”. The other one would mean “I only understand hiragana” which, to my understanding, doesn’t mean they’d even necessarily be able to understand Japanese but could just be able to read the characters
@Leebo This is the bit that’s causing confusion, I think. (Additional emphasis mine.)
@lutzky As Leebo said, it’s definitely closer to ‘if’ than ‘only’.
The short version: なら is essentially the same thing as だったら (=‘if it’s ~ ([someone] is talking about/discussing/looking for etc)’), but a little more formal. If you’re writing formally, you’ll want to use なら instead of だったら, generally. (Another way I see it is as an emphasised は, but this is a purely personal idea with no historical basis. If it confuses you instead of helping you, then ignore it, because I might just see things differently.) なら highlights a particular case for discussion and limits the discussion to that topic. It doesn’t, however, provide information on things not discussed.
In contrast, だけ is a word that expresses limits and extents, which are really two sides of the same coin (if you define a limit, you make gauging the extent of something possible), and that’s why it’s used to mean ‘only’. If you use だけ, you are saying that something is true for what you mention, but nothing else.
@TheMunichMunch’s explanation is clear and intuitive, so if that has already allowed you to understand, you can stop here. If you want to know possible historical reasons for why the two words are very different, particularly with regard to their origins, read on. (Heads up: I’m going to start using technical language.)
Reasons & explanations for the difference
If we’re talking about word origins, なら comes from the 未然形（みぜんけい）of なり, which is the old copula (i.e. the word that translates as ‘to be’, more or less. Today’s equivalent is です・だ・である). The 未然形 is called the ‘irrealis’ in technical language, and, as the name suggests, is used when discussing things that are not real or which haven’t taken place, like for negation (i.e. ‘not [verb]’, which we still see today – the irrealis is the verb stem ending in ‘-A’ used for godan verb negation) and for purely hypothetical situations (this usage only exists in Classical Japanese).
In modern Japanese, なら has become the ‘hypothetical form’ (仮定形（かていけい）) of the verb だ. In other words, なら is currently the ば-conditional verb stem of だ, which is why ならば exists, just like how できれば exists. (By the way, ならば means more or less the same thing as なら, just that it’s even more formal. For example, the first line of the famous Japanese song Lemon:「夢ならば、どれほどよかったでしょう〜」=‘if it were a dream, how wonderful it would be.’) As such, なら is really just the ‘if’ form/conditional form of だ. As @TheMunichMunch said, it frames something as a condition or, as 大辞林 says, it ‘raises the topic of the sentence’. Notice how the word ‘raise’ (取り上げる（とりあげる）) is used – it’s a step above は, which simply marks the topic. My personal way of translating 〜なら is ‘in the case of ~’. The other translations proposed so far are fine too, but I hope that you can see that if you’re discussing a specific ‘case’, then as Genki says, what follows only applies to that case. We do not know if it is valid for everything else, but we are saying, by using なら, that it is true in one specific case. Does that clear things up?
We now know that なら is basically a form of だ. It’s essentially a verb. On the other hand, だけ behaves like a noun in grammatical constructions, even though it creates adverbial phrases. (For example, when you put a な-adjective in front of だけ, you have to say 〜なだけ.) Why is that? The answer: it comes from a noun – 丈（たけ）. Here are 丈’s first three definitions in 大辞林 translated and shortened:
② The length of an object, especially of parts of clothing
③ A certain limit. The entirety of something.
In other words, だけ comes from a word that refers to the measure of something, or to a certain limit. That’s why it means both ‘only’ and ‘insofar as/to the extent that’ (e.g. できるだけ〜=as ~ as possible/as one can). If you use だけ, you are saying that something is exclusive. Nothing else has that property. You clearly state something about both what’s being discussed and what hasn’t been discussed. なら doesn’t have that kind of impact in and of itself, though it can imply that, perhaps, what’s true for a ‘specific case’ may not be true elsewhere. However, I’d like to emphasise this again: strictly speaking, なら does not provide information about anything that hasn’t been mentioned in a sentence. Any implications are purely a result of context and reader/listener assumptions. だけ, on the other hand, excludes everything else.
All in all, I hope it’s now clear what each word means, and why there’s no reason to confuse the two once you know how they work.
I guess because they used the word “only” there, huh. If you said “predicate X applies if it’s noun A, but not in other cases” maybe that avoids the confusion with the idea that it could be similar to “Only noun A” like だけ.
Yeah, it would probably have been better to use ‘if’ in the explanation. I think なら is usually discussed with other conditional structures anyway. The Tokyo University of Foreign Studies lists it on their page discussing と、たら and ば.
Maybe the Genki authors just wanted to avoid suggesting that なら necessarily excludes other possibilities? At least, it doesn’t in my understanding. (But ok, actually, you could just say ‘predicate X applies if it’s noun A, but not necessarily in other cases’ and be done with it…)