As mentioned in our lesson about
ば,
なら is often used by itself to mean ‘if’. This is considered to be an abbreviation of
ならば, the 仮定（かてい） (hypothesis) form of なり, a classical auxiliary verb that is not used much in modern Japanese.
Because なり originally meant ‘to be’, it functions in a similar way to the 助動詞（じょどうし） (auxiliary verb)
だ. This means that it regularly pairs with nouns, or phrases that have been
nominalized (become noun-like), though the use of
の.
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田舎（いなか）に住（す）むのならば、車（くるま）を買（か）ったほうがいい。
If you are going to live in the countryside, it would be better to buy a car.
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寒（さむ）いのならば、ジャケットを着（き）るといいだろう。
If it is cold, you should wear a jacket.
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無理（むり）ならいいよ。
If it is not possible, it's okay.
-
デザートなら何（なん）でも食（た）べられます。
If it is a dessert, I can eat anything. (If it is dessert, I like anything)
However, unlike
だ (or
です),
なら is also regularly used without the extra help of
の for nominalization, and can be attached directly to verbs or
い-Adjectives.
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私（わたし）の車（くるま）を使（つか） うなら、いつ使（つか）うか教（おし）えてください。
If you are going to use my car, please let me know when.
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暑（あつ）いなら、その上着（うわぎ）を脱（ぬ）いでください。
If you are hot, please take off that jacket.
Because
なら is an abbreviation of
ならば, it is strictly used when making guesses about what ‘may’, or what ‘could’ happen in certain situations. This means that it will not be used as ‘if’ in statements about results that are produced through some sort of effort/training.
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練習（れんしゅう）をするなら、漢字（かんじ）を書（か）くのが上手（じょうず）になる。
If you are going to practice, you will get good at writing kanji. (Unnatural Japanese, as becoming ‘good’ is a natural result of practicing)
Although なら comes from the classical auxiliary verb なり, it should not be confused with the particle なり, which often has the meaning of ‘as soon as’, or ‘just after’. Thankfully, the particle なり is also quite uncommon in modern Japanese.