"Should" in Japanese


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.?




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.




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.

