～べき(だ)

About

べき is an auxiliary verb that means "should" or "ought to", and is used to express what the speaker feels one "ought to do", or how one "ought to act". べき attaches to casual form verbs.

E.g. 学生がくせいはちゃんと勉強べんきょうするべきだ。 "Students ought to study properly."

べき sounds quite strong and tends to be used for moral/societal responsibilities, or sometimes to strengthen a suggestion one feels strongly about.

If べき comes at the end of a sentence, it is almost always followed by だ or です. However, だ・です will sometimes get dropped in spoken language.

To make a negative べき statement, use じゃない or the formal ではない.

E.g. 人ひとを殺ころすべきではない。 "You ought not to kill people."

Summary

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  べき means "should" or "ought to"

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  べき tends to be used to express moral/societal responsibilities

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  べき can be made negative using ではない・じゃない