Only natural that, Inevitable that, Bound to
This expression is used to indicate that the occurrence of something is natural or inevitable and is based on people’s beliefs or upon generally known facts. It is also used in the form -게 마련이다.
1. This expression can only be used when the object refers to general things or categories and not when it refers to something specific. When this expression is used in a negative sentence, the form -지 않기 마련이다 is used.
2. This expression cannot be used in interrogative, imperative, or propositive sentences.
3. This expression cannot be used with the form -아/어야 하다 indicating necessity.
4. This expression can only be used in the present or past tense because it indicates a view based on the speaker’s observations of general and universal laws and tendencies as understood from the speaker’s accumulated past experiences up to the present.