In every language, there’s a common pattern of the most useful words being the most complicated and confusing. This is a natural consequence from the fact that the word must cover many different types of usages and meanings in order to be so useful. Due to its usefulness, it will also often go through various types of abbreviations and shortcuts to facilitate speaking, further complicating the issue. This post will cover what could arguably be the most useful and hence the most intricate word in Japanese: 「いい」. We’ll see that this word is much more expansive in scope and usage than the English equivalent word “good”. Just learning the definition is barely scratching the surface of this useful word.

Briefly on Conjugation

I’ll assume that most readers are already familiar with many of the discrepancies in the conjugation rules for 「いい」 and so I’ll just briefly mention that the discrepancies are all caused by the change from 「よい」 to 「いい」. This word is so useful and so often used that even the slight pursing of the lips to pronounce 「よ」 seemed to tax Japanese speakers and was eventually changed to 「いい」. The newer version has the added convenience of removing one pronunciation completely and replacing it with a single longer pronunciation of 「い」. The older version is now considered formal and old-fashioned. Unfortunately, many of the conjugated forms such as the negative （よくない） failed to transition over to the new pronunciation hence creating a number of discrepancies which annoy Japanese beginners to this day.

To get the full scoop, check out my page on adjectives on my grammar guide. Now let’s look at the various ways this adjective can be used. You’ll also see how these patterns translate to very different things in English and yet is just a simple adjective with some grammar patterns in Japanese.

Using 「いい」 for permission

The usage of 「いい」 for asking and granting permission is just another example of the fundamental difference between Japanese and English, as well as, a great example of how vital it is to understand how 「いい」 is used in various grammatical patterns.

In English you use words like “can” or “may” to ask for permission, in Japanese the word 「できる」 is reserved only for the ability to do something, not on whether it’s permitted or not. (This is similar to the difference between 能/会 and 行 in Chinese.)

In Japanese, you ask for permission by asking literally, “Is it good even if I…”.　I’m sure many of you in Japanese class learned the phrase: 「トイレに行ってもいいですか？」 This literally means, “Is it good even if I go to the bathroom?” Your teacher may respond by saying either 「いいです」 or 「だめです」 (or the very formal 「いけません」). There’s a logical discrepancy here in that the positive answer is 「いい」 but the negative answer is not simply the negative: 「よくない」. This is because the 「てはいけない／てはならない／てはだめ」 grammar pattern set for saying you can’t do something is separate from the one that says you can do something.

However, while saying “can” versus “can’t” is not as easy in Japanese as saying 「いい」 versus 「よくない」, there is one very useful way to use negatives with the 「V～てもいい」 pattern. You can negate the verb in front to have 「～なくてもいい」. Let’s see how this translates literally for the example: 「行ってもいい」.

1. 行ってもいい。
– It’s good even if [you] go.

2. 行かなくてもいい。
– It’s good even if [you] don’t go.

Can you guess what the examples translates to in English? The first means, “You can go” while the second means “You don’t have to go”. Once again, you have two completely different grammar patterns in one language while the other is just the negative and positive version of the same grammar pattern. Except this time, it’s the other way around. This is another example of why it’s best to work in the target language as opposed to trying to tie everything into English.

Let’s look at the following example short conversation at a training seminar.

Aさん)　トイレに行ってもいいですか？
Bさん)　いいですよ。これは授業じゃないから、聞かなくてもいいですよ。
Aさん)　じゃ、戻らなくてもいいですか？
Bさん）　だめです。

This next dialog shows how slang can hide these grammar patterns but still have the same meaning. In the dialog, Aさん is not asking if the pen is a little good.

Aさん）　そのペン、ちょっといい？
Bさん）　だめ。俺、使っているよ？
Aさん）　いいから早く貸して。

Using 「いい」 for good result

There are many variations to this usage but the basic idea is to show a good result as a result of something. The most basic example of this usage is to make a suggestion.

例）　病院に行った方がいい。
– The side of going to hospital is good. (You should go to the hospital.)

例）　どこに行けばいいですか？
– If [I] go, where is good? (Where should I go?)

Notice the non-literal translation uses the same word “should” but as you can see, the word “should” has many meanings which are expressed differently in Japanese. The first is a general suggestion such as “you should see a doctor” or “you should get some more sleep” while the second is conditional on the situation such as “Which way should I go if I wanted to go to the mall?” or “Where should I write my name?”

You can also use the past tense to talk about what you did (relief) or should have done (wishful thinking).

例）　早く予約してよかった！
– [I] made reservation early and it was good! (Good thing I made the reservation earlier!)

例）　早く予約すればよかった！
– If [I] had made reservation early it would have been good! (I should have made the reservation earlier.)

Again, you really can’t directly translate English phrases like “Good thing I…” or “I should have…”, you have to use a grammar pattern and 「いい」 to express a similar thing.

Here’s another example conversation.

Aさん）　頭が痛い。
Bさん）　コンビにで薬を買った方がいいよ。
Aさん）　どこのコンビニに行けばいいの？
Bさん）　駅の近くにあると思う。
Aさん）　今日仕事休めばよかった。

Conclusion

In writing this article, I surprised even myself on all the various hidden but essential ways 「いい」 is used in the Japanese language. It can be expressed to indicated things you should do, things that are allowed, things you don’t have to do, and much more. I hope this article helped you realize the importance mastering the many uses of 「いい」 and why it’s better to approach it from Japanese instead of from English.

Am I missing any important usages here? Let me know in the comments!