Things that should be a certain way

In this lesson, we'll learn how to express the way things are supposed depending on what we mean by "supposed". While the first two grammar points 「はず」 and 「べき」 come up often and are quite useful, you'll rarely ever encounter 「べく」 or 「べからず」. You can safely skip those lessons unless you are studying for the １級日本語検定.

Using 「はず」 to describe an expectation

The first grammar we will learn is 「はず」, which is used to express something that was or is supposed to be. You can treat 「はず」 just like a regular noun as it is usually attached to the adjective or verb that is supposed to be or supposed to happen.

The only thing to be careful about here is expressing an expectation of something not happening. To do this, you must use the negative existence verb 「ない」 to say that such an expectation does not exist. This might be in the form of 「～はずがない」 or 「～はずはない」 depending on which particle you want to use. The negative conjugation 「はずじゃない」 is really only used when you want to confirm in a positive sense such as 「～はずじゃないか？」.

Examples

1. 彼は漫画マニアだから、これらをもう全部読んだはずだよ。
   He has a mania for comic book(s) so I expect he read all these already.
2. この料理はおいしいはずだったが、焦げちゃって、まずくなった。
   This dish was expected to be tasty but it burned and became distasteful.
3. 色々予定してあるから、今年は楽しいクリスマスのはず。
   Because various things have been planned out, I expect a fun Christmas this year.
4. そう簡単に直せるはずがないよ。
   It's not supposed to be that easy to fix.
5. 打合せは毎週２時から始まるはずじゃないですか？
   This meeting is supposed to start every week at 2 o'clock, isn't it?

Here are more examples from the WWWJDIC.
You may also want to check out the jeKai entry.

Using 「べき」 to describe actions one should do

「べき」 is a verb suffix used to describe something that is supposed to be done. This suffix is commonly defined as "should", however, one must realize that it cannot be used to make suggestions like the sentence, "You should go to the doctor." If you use 「べき」, it sounds more like, "You are supposed to go to the doctor." 「べき」 has a much stronger tone and makes you sound like a know-it-all telling people what to do. For making suggestions, it is customary to use the comparison 「方がいい」 grammar instead. For this reason, this grammar is almost never used to directly tell someone what to do. It is usually used in reference to oneself where you can be as bossy as you want or in a neutral context where circumstances dictate what is proper and what is not. One such example would be a sentence like, "We are supposed to raise our kids properly with a good education."

Unlike the 「はず」 grammar, there is no expectation that something is going to happen. Rather, this grammar describes what one should do in a given circumstance. In Japanese, you might define it as meaning 「絶対ではないが、強く推奨されている」.

There is very little of grammatical interest. 「べき」 works just like a regular noun and so you can conjugated it as 「べきじゃない」、「べきだった」, and so on. The only thing to note here is that when you're using it with 「する」, the verb meaning "to do", you can optionally drop the 「る」 from 「するべき」 to produce 「すべき」. You can do this with this verb only and it does not apply for any other verbs even if the verb is written as 「する」 such as 「擦る」, the verb meaning "to rub".

Examples

1. 何かを買う前に本当に必要かどうかをよく考えるべきだ。
   Before buying something, one should think well on whether it's really necessary or not.
2. 例え国のためであっても、国民を騙すべきではないと思う。
   Even if it is, for example, for the country, I don't think the country's citizens should be deceived.
3. 預金者が大手銀行を相手取って訴訟を起こすケースも出ており、金融庁は被害者の救済を優先させて、金融機関に犯罪防止対策の強化を促すべきだと判断。（朝日新聞）
   With cases coming out of depositors suing large banks, the Financial Services Agency decided it should prioritize relief for victims and urge banks to strengthen measures for crime prevention.

Using 「べく」 to describe what one tries to do

Grammatically, 「べく」 is really a conjunctive form （連用形） of 「べき」, similar to what the te-form does to connect another phrase. However, what needs mentioning here is that by changing it into a conjunctive and adding a predicate, the meaning of 「べく」 changes from the ordinary meaning of 「べき」. While 「べき」 describes a strong suggestion, changing it to 「べく」 allows you to describe what one did in order to carry out that suggestion. Take a look that the following examples to see how the meaning changes.

1. 早く帰るべき。
   Should go home early.
2. 早く帰るべく、準備をし始めた。
   In trying to go home early, started the preparations.

As we can see in this example, adding the 「準備をし始めた」 tells us what the subject did in order to carry out the action he/she was supposed to do.In this way we can define 「べく」 as meaning, "in order to" or "in an effort to". Similarly, 「べく」 might mean the Japanese equivalent of 「しようと思って」 or 「できるように」. This is a very seldom-used old-fashioned expression and is merely presented here to completely cover all aspects of 「べき」.

Examples

1. 試験に合格すべく、皆一生懸命に勉強している。
   Everybody is studying very hard in an effort to pass the exam.
2. 今後もお客様との対話の窓口として、より充実していくべく努力してまいります
   We are working from here in an effort to provide a enriched window for customer interaction.

Using 「べからず」 to describe things one must not do

Moving on to yet another from of 「べき」 is 「べからず」. This is undoubtedly related to the 「ず」 negative ending we learned in a previous section. However, it seems to be a conjugation of an old 未然形 of 「べから」. I have no idea what that means and you don't have to either. The only thing we need to take away from this is that 「べからず」 expresses the opposite meaning of 「べき」 as an action that one must not do. I suppose the short abrupt ending of the 「ず」 form makes this more useful for laying out rules. In fact, searching around on google comes up with a bunch of 「べし･ベからず」 or "do's and don'ts". （べし is an even older form of べき, which I doubt you'll ever need.)

Examples

1. ゴミ捨てるべからず。
   You must not throw away trash.
2. 安全措置を忘れるべからず。
   You must not forget the safety measures.