Japanese: Conditionals
This is much more complicated than I thought. There are many ways to express conditionals (“if” or “when”) in Japanese. I will leave out some of the more nuanced rules that I don’t really get. Future me can refer to the sources if i see a usage that doesn’t fit with the rules I wrote down.
Sources:
Method 1: と
Structure: Add と to a condition (predicate). The preceding condition follows the usual rules of embedded predicates: verbals in plain / direct style, adjectivals i-form without desu, and nominals + だ.
Use:
1 - Describing a natural / habitual relationship, where result is non-volitional and always happens if the condition is true.
早く行かないと、負けります - “If you don’t go quickly, you will lose”
たくさん食べると太るよ - “If you eat a lot, you will get fat”
ボールを落すと落ちる - “If you drop the ball, it will fall”
2 - Also, can be used to recount a past series of cause and effect events. But in this case, the condition cannot be in past tense.
窓を開けると、風が入ってきた - “When I opened the window, the wind (a breeze) came in”
Method 2: なら
There is also the politer version, ならば, which is used exactly the same.
Structure: Attach directly to plain form verbal, i-form adjectival, or nominal. Note, you don’t need だ for the nominal.
Use:
1 - When assuming the condition is true (based on information learned previously).
スーパーに行くのなら、しょうゆを買ってきて - “If you are going to the supermarket (mentioned earlier), bring back some soy sauce”
乗るなら、飲むな - “If you are going to drive, don’t drink”
Method 3: ば
The “provisional form” of verbals and stuff.
Structure: For verbals, take the dictionary form and change the last kana to the corresponding え sound and add ば. For adjectivals, drop the ending い and add ければ. For nominals add であれば, which is the ば form of the formal expression である.
Use:
1 - When talking about something that hasn’t happened yet, and you want to emphasize the conditional. Can be translated to “if and only if” / “all you need to do”.
果物を食べれば健康になる - “All you need to do to become healthy is to eat fruit”
楽しければ、私も行く - “Only if it is fun, I will go”
彼女はきれいであれば、会います - “I will meet her if and only if she is pretty”
どうすれば、東大に入学できますか - “To get into Tokyo University, what should I do?”
2 - When talking about what would happen if a condition (which is not true) were true.
彼女があればいいね - “If I had a girlfriend, it would be good, huh?”
Note, if the succeeding clause ends with a negative, it sounds unnatural, and you are better off using と or たら.
Method 4: たら
The “conditional form” of verbals and stuff. ならば is the more formal version.
Structure: Take the conditional predicate, turn it into past tense, and add ら.
Use:
1 - Ephasises on the reaction to the condition. Commonly used if the reaction is a intent, desire, or command (that should be emphasized). Sometimes interchangable with ば, like if you are unsure if a future condition will be true. But, unlike ば, you can use たら, it is fact that condition will be true. And, unlike ば, you can also use it for things that happened in the past.
雨が降ったら、どうしますか - “If it rains, what should we do?” - ば interchangable
午後になったら、一緒出かけましょう - “Let’s go out together in the afternoon” / “When it becomes afternoon, let’s go out together” - ば not interchangable
それが手紙だったら、嬉しいです - “If it was a letter, I am happy”
2 - Can use similar to と, for cause and effect relationship.
田中さんにメールを送ったら、すぐ返事が来ました - “When I texted Ms. Tanaka, I got a reply right away”
Side Note: もし
もし is used to suplement a conditional clause. It adds uncertainty to if the condition is true. Similar to “if by any chance” in English.
もしよかったら、一緒映画を見に行きませんか - “If by any chance it’s ok, would you like to go and see a movie together?”
もし時間がないなら、明日もいいよ - “If, for some reason, there isn’t time (you don’t have time) (like you mentioned earlier), tomorrow is also good”
Other Notes
Also I’ve found that these conditionals are often used to represent “when”. Like:
学校が終わったら... - “When school ends” / “If school ends”