The word "should" in English has these uses when not used as a question:

  1. To express the expectation of the speaker (Probabilistic reasoning).
    • The train should arrive in 10 minutes.
  2. To express a condition
    • Should it rain, the event will be cancelled.
  3. To express obligation or the duty of ~.
    • I should go home.
    • You should study hard for the exam.
  4. To indicate an ideal state perceived by the speaker.
    • Everyone should have equal rights.

From my understanding, I use ~はず for 1., ~ば(or other conditionals) for 2., and ~べき for 3. .

(Question) What can I use for 4.?

  • 3
    What is the difference between 3 and 4?
    – user458
    Nov 2, 2011 at 3:24
  • @sawa Actually I'm having a hard time differentiating them now that you mention it. I'd say in 3., someone owns the "obligation" or "duty". But in 4. there isn't an owner.
    – Flaw
    Nov 2, 2011 at 3:30
  • 3
    In 3, it is something that is controllable by the subject. In the second example of 3, it seems that it urges the listener to study more than it expresses obligation. On the other hand, "Parents should take care of their children" would express a sense of obligation or duty. Nov 2, 2011 at 3:41

2 Answers 2


2 could also use 場合 to be a little more formal (雨の場合は...). 3 can also use ~もの as another option to ~べき (猛勉強するものだよ!).

4 lacks a little context. While most of the time it will be perceived as subjective (i.e., "(It's my opinion that) Everyone should have equal rights," it could also be objective in a few circumstances. For example, "A new law passed. Therefore, everyone should have equal rights (now)," or something similar. Each case would use something different, and I'm thinking ~べき again if it's subjective and ~はず if it's objective.

I'd also add a #5 to your list: subjective recommendation, for which you could use 〜たほうがいい (and, I believe, also 〜たらいい or 〜ばいい).

お前、風邪【≪かぜ≫】気味【ぎ・み】だね。今日学校を休んだほうがいい。 → You seem sick. You should stay home from school today.

  • Is this true of もの with 3? I could see こと...
    – Hyperworm
    Nov 2, 2011 at 13:13
  • I'm not sure I understand your question. Is what true of もの with 3?
    – istrasci
    Nov 2, 2011 at 15:09
  • I was asking if someone could back up your statement that 3 can use もの instead of べき (it seems to me like the meaning would be entirely different - "people do" or something rather than "you should"). Sorry if I'm mistaken here ^^;
    – Hyperworm
    Nov 2, 2011 at 20:05
  • No, this もの is not "person". It's the "thing" definition of もの.
    – istrasci
    Nov 2, 2011 at 21:50
  • 2
    That's 大辞泉 ;) Actually, 大辞林 does clarify things for me. It has 〔4〕[1](ア)普遍的な 傾向 。 (the definition I know - "It is the natural way of things to" = "People, in general, do") 「どんな人もお世辞には弱い―だ」「人間はとかく過去を美化したがる―らしい」, but it also has 〔4〕[1](イ) なすべきこと。 「そんな時は何も聞かずにいてあげる―だ」. I wasn't aware of this second sense. I may have interpreted it as "In times like that, one tends to say nothing and just be there for them", and would have expected こと rather than もの for the べき meaning. Today I learned :)
    – Hyperworm
    Nov 3, 2011 at 2:15

TL;DR You should be able to use ~はず or ~べき to indicate an ideal state perceived by the speaker, but a phrase that contains 理想 would help to emphasize that fact.

1. To express the expectation of the speaker (Probabilistic reasoning)

You say that you would use はず in this case, but given your sample sentence that sounds a bit too strong (unless you are really trying to emphasize the point). I think that ~だろう/~でしょう or even ~よう would be perfectly acceptable and probably more common.

"The train should arrive in 10 minutes."

電車はあと十分で来るでしょう。 (when you are expressing your belief or opinion)

電車はあと十分で来るようです。 (after looking at a timetable)

2. To express a condition

I agree with you in saying that ~ば (or some other conditional) would be appropriate in this case.

"Should it rain, the event will be cancelled."


3. To express obligation or the duty of ~

You say that you would use ~べき in this case, but the following would also work just as well.

  • ~なければならい
  • ~なければいけない
  • ~ないといけない

In fact, I think that these are used more often than ~べき.

"I should go home."


"You should study hard for the exam."


Note that you can also use こと to express obligations (I often see this in bulleted lists).

"You should study every day."


4. To indicate an ideal state perceived by the speaker

Here I think that you could use either ~はず or ~べき, but to make it clear that you're talking about an ideal state it would probably help to start your sentence with a phrase containing 理想.

"Everyone should have equal rights."


  • 本来なら皆には平等権があるべし is incorrect for many reasons. Nov 4, 2011 at 2:00
  • @TsuyoshiIto Could you kindly elaborate?
    – Flaw
    Nov 4, 2011 at 13:37
  • @Flaw: (1) は in 皆には is wrong in this context. (2) “平等権” means “the right to be equal,” not “equal rights.” (3) In modern Japanese, the auxiliary verb べし is only used in conjugated forms such as べき and べく. Nov 4, 2011 at 21:12

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