~기/게 마련이다

This pattern expresses that the state of affairs in question comes about as a matter of course, according to normal shared common knowledge. The textbook citation form is ~기/게 마련이- (the nominalizer ~기 OR the adverbial ending ~게 + the noun 마련 + the bare copula -이-).

Both ~기 마련이다 and ~게 마련이다 are equivalent. There is no perceptible change in meaning. The ~기 form is more common in modern usage, but the ~게 form is fully grammatical and you’ll see it in older texts and formal writing.

Etymology note: 마련 is an independent noun meaning “preparation” or “arrangement.” With -하-, it forms the verb 마련하다 (“to prepare”). When combined with a nominalizer (~기 or ~게), the noun takes on the extended meaning “is bound to, is doomed to, is expected to, is normal to.” The pattern frames the outcome as part of the natural order of things.

Value-neutral, not pessimistic: Despite a tendency in some learning materials to list mostly negative examples, ~기 마련이다 covers positive, neutral, and negative outcomes equally. The textbook examples span the full range:

• Positive: 부모는 자식에게 관대하기 마련 — parents are lenient with their children
• Neutral observation: 술을 많이 마시다 보면 취하기 마련 — drinking heavily naturally leads to getting drunk
• Melancholy: 사랑은 언젠가 식기 마련 — love grows cold with time
• Proverbial inevitable: 사람은 누구나 죽기 마련 — everyone dies

The unifying frame is “shared common knowledge / part of how the world works,” not pessimism.

How to attach it:

• Verb/adjective stem + ~기 마련이다 (more common)

  • 죽다 → 죽기 마련이다
  • 관대하다 → 관대하기 마련이다
  • 식다 → 식기 마련이다

• Verb/adjective stem + ~게 마련이다 (equivalent, less common in modern usage)

  • 죽다 → 죽게 마련이다
  • 관대하다 → 관대하게 마련이다

• Past tense: the pattern itself stays in present form. The surrounding clause carries any tense information.

• Common collocations: the pattern often follows a conditional or generalizing setup:

  • 술을 많이 마시다 보면 취하기 마련이에요. (If you drink a lot, you naturally get drunk.)
  • 시간이 지나면 잊어버리기 마련이지요. (As time passes, you’re bound to forget.)

Polite form: ~기 마련이에요 / ~기 마련입니다

Compared to ~(으)ㄹ 수밖에 없다: Both express necessity, but ~기/게 마련이다 frames the outcome as a natural law of the world, drawing on shared common knowledge (“this is just how it goes”). ~(으)ㄹ 수밖에 없다 frames it as having no other choice in this specific case. Use ~기 마련이다 for proverbial / generalizing observations; use ~(으)ㄹ 수밖에 없다 for situational compulsion.

Tip: Common in essays, opinion columns, and proverbial-sounding statements. You’ll often see it after a generalization about people, life, or society: 사람은…, 인생은…, 시간이 지나면…, 부모는…, 사랑은…. The pattern thrives wherever the speaker is appealing to “everyone knows that…” common-sense inference.