べからず
- 1Expresses a firm prohibition on public signs and notices ("Do not ~").Ex. 1
- 2States a rule or principle forbidding an action in a given situation.Ex. 2
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This is a written, old-fashioned form found mainly on signs, notices, regulations and set sayings such as 働かざる者食うべからず. Compared with modern prohibitions like てはいけない or てはならない, it sounds terse, authoritative and classical. In speech it mostly appears when quoting a rule or proverb, or when used jokingly for a mock-solemn effect.
Do not use べからず in ordinary conversation as a normal way to forbid something, because it sounds archaic and stiff.
Learners should attach it to the dictionary form, not the ます-form or other conjugated forms.
Do not confuse べからず with すべからく, which is an adverb meaning "as a matter of course" or "by all means."
- てはならないN2「てはならない」attaches to the て-form of verbs, and can also attach to adjectives and nouns. Beyond prohibiting things in rules and regulations, it can also express moral admonition or that something must never happen. When used for rule-based prohibitions, it is interchangeable with 「べからず」, with a formal tone but without the classical signboard flavor.
- べきではないN3「べきではない」expresses a judgment that something 'should not' be done based on reason, with a neutral register, used for advice or criticism; it can also be said as 「べきではなかった」 to express regret. 「べからず」, by contrast, is a signboard-style written prohibition that attaches only to verbs, so the two are generally not interchangeable.
- まじきN1「まじき」only modifies nouns attributively and cannot end a sentence; as a predicate you must say 「まじきことだ」, which is similar to the attributive use of 「べからざる」. It carries strong moral condemnation and often appears as 「にあるまじき」 to criticize behavior unbefitting one's position; it is not used for signboard prohibitions.
- てはいけないN5「てはいけない」attaches to the て-form of verbs, and can also attach to adjectives and nouns to mean '... won't do' or '... would be no good'. Its register is neutral, usable in both speech and writing. Only its prohibitive sense is close to 「べからず」; when stopping someone in everyday conversation, use this instead.
- なN5「な」also attaches to the dictionary form of verbs to express strong prohibition, but it is colloquial, mostly used to stop someone face-to-face, with a rough tone. 「べからず」is classical written language, leaning toward signs and regulations, and can also modify nouns as 「べからざる」—something 「な」cannot do.
てはならない and てはいけない are the modern ways to say "must not," and な is a blunt spoken command, whereas べからず is a classical written prohibition typical of signs and rules. べきではない gives advice ("should not") rather than issuing a command, and まじき is an attributive form meaning "unbecoming of" (e.g., 教師にあるまじき行為).
