Does 은/는 always imply contrast? How do you know when it doesn’t?

Question

I have looked at many different sources and they seem to be saying similar things. That these particles are used for emphasis on the predicate, contrast, and old information.

What I’m confused about is when are the particles used for contrast and when are the particles used for emphasis on a predicate? For example, does “지안은 철수를 좋아한다” mean that 지안, not someone else, likes 철수? Or does it mean that 지안 likes, not hates, 철수?

If person A asked who broke the cup, (let’s say person C broke it) and person B claims they broke it, would person C say “제가 broke it” (idk what “break” is in Korean, I’m still very much a beginner) or “나는 (or whatever correct 은/는 version of I) broke it”?

I’m sorry if that was confusing I’ll try to rephrase it.

Notes: I’m a beginner, and idk what “break” is in Korean (Google translate is no help), nor do I know what the correct version of “I” should be used

A: “Who broke the cup?” (C broke it)

B: “제가 broke it”

C: “나는/(the correct “I” with 는) broke it” or “제가 broke it”?

Answer 1

does “지안은 철수를 좋아한다” mean that 지안, not someone else, likes 철수?

By itself, no, but in a certain context it could. E.g. 민지는 지민을 좋아하는데 지안은 철수를 좋아한다.

Or does it mean that 지안 likes, not hates, 철수?

No, nothing about that sentence in itself implies this nuance. This kind of implication would be done through intonation when speaking.

If person A asked who broke the cup, (let’s say person C broke it) and person B claims they broke it, would person C say “제가 broke it” (idk what “break” is in Korean, I’m still very much a beginner) or “나는 (or whatever correct 은/는 version of I) broke it”?

C: “나는/(the correct “I” with 는) broke it” or “제가 broke it”?

Both are possible (which is usually the case with the subject) but 이/가 would be more common here (제가/내가).

I strongly believe there is no way to learn the nuances of 는/은 vs 이/가 without hundreds (or honestly, thousands) of hours of exposure, no matter how many grammar books you read. As such I would not recommend spending much time on it at the beginner stage as it could be spent in much more useful ways, no matter how frustrating it might feel at first to have to "let it go".

Answer 2

The fundamental distinction between 은/는 and 이/가 is that

1. 은/는 tends to state something the speaker knows well, feels strongly about, or otherwise invested some thoughts in. For example, when you introduce yourself, you'd start with 나는 (나는 XX 대학교 다니는 영수야); to say you're happy, 나는 행복하다, since you're saying it because you felt that way in your heart.

2. 이/가 is more about facts and necessity. The speaker says it, often about an external thing rather than what they have been thinking, because the circumstance or context demands it. For example, if you just saw a car speeding by, you might say 차가 너무 빨리 달린다, since you're responding to an unexpected external situation which is a speeding car.

지안은 철수를 좋아한다 is thus stating what the speaker knows or thinks (i.e. he/she saw their behavior and history, and drew this conclusion). Whether it is contrasting or not is largely determined by the context. If there was a mention of another person liking someone, it would be taken as contrasting 지안 to that person; otherwise, it would be an independent sentence.

When asked 누가 컵을 꺴어? (Who broke the cup?), the person answers 제가 깼어요 (I broke it) with 이/가, because he/she is just supplying a fact in response to an external need (the question), not what he/she was thinking about on their own.

은/는 often contrasts things, and this might be a natural consequence of its intrinsic function of expressing subjective thought. For example, if you have two kids A and B and say A is very smart, the implication may be that B is less so, making a contrast between them whether you intended or not.

이/가 has little of this effect, because it's about accidental facts, like "A fire broke out in the downtown last night" (어젯밤에 시내에서 화재가 발생했다), for example.

So 은/는 is the natural way to express one's own thoughts. Most textbooks, Wikipedia articles, and anything explaining something will use it. On the other hand, referring to a specific real life occurrence or anecdotal facts will use 이/가.

Another example on how 은/는 is from what one thinks/knows/feels whereas 이/가 is specific to circumstantial/specific facts.

1. 하늘은 푸르다 (The sky is blue). => states what one believes in general.
2. 하늘이 노랗다 (The sky is yellow (right now)). => states what one sees at the specific moment.
   (it's a figurative way of saying one has acute dizziness/nausea that makes one see things yellow, not a literal statement).

And another:

• 내가 부산에 도착했을 때, 거리에는 어둠이 깃들고 있었다 (When I arrived in Busan, darkness was descending on the streets).

You say 내가 because arriving at the place is just supplying a circumstantial fact. It is not something you've been thinking or feeling. 이 in 어둠이 also describes an external occurrence, not your own thought. (는 in 거리에는 is a different kind of 은/는 usage, not marking a subject but attaching to the particle 에. This adds emphasis or contrast in an adverbial phrase.)