Grammar · 12 min read

Korean Particles 이/가 vs 은/는: What Linguists Actually Say

The standard rule that 이/가 is subject and 은/는 is topic breaks down fast. Here is what 50 years of linguistics research actually says.

이/가 vs 은/는. If you've studied Korean for more than a week, you've heard the standard explanation: "이/가 marks the subject, 은/는 marks the topic." And then you tried to use this in a real conversation, and it fell apart immediately.

You're not alone. This is widely considered the hardest grammar point in Korean, not just for learners, but for linguists too. Dozens of academic papers have been written trying to pin it down, and they still don't fully agree. In this article, I'll walk you through what the research actually says and give you the mental model that finally makes these particles click.

Why the Standard Explanation Fails

Most textbooks give you this:

• 은/는 = topic marker
• 이/가 = subject marker

But this immediately raises the question: what's the difference between a topic and a subject? In English, they're almost always the same thing. "The dog barked": "the dog" is both the grammatical subject and the topic (what the sentence is about). English doesn't force you to distinguish them.

Korean does. And that's exactly why this is hard for English speakers.

A 1976 Paper That Changed Everything

In 1976, linguists Charles Li and Sandra Thompson published a paper that would become foundational in language typology: "Subject and Topic: A New Typology of Language." Their key insight was that languages organize information differently at a fundamental level.

Some languages (like English) are subject-prominent: the sentence revolves around a grammatical subject. Others (like Korean and Japanese) are topic-prominent: the sentence revolves around a topic, a separate grammatical category that doesn't exist in English.

This is why you can't directly translate 은/는 into English. There's no English equivalent. The closest we get is "As for X…" or "Speaking of X…", which sounds stiff in English, but is completely natural and neutral in Korean.

These sentences are both grammatical. But they're not interchangeable, and the difference isn't stylistic. It's semantic.

The Four Functions You Need to Know

1. 은/는: Marking the Topic (Given Information)

The core function of 은/는 is to mark information that is already established: something both speaker and listener already know, or something being set up as the frame for what follows.

Linguist Wallace Chafe (1976) described this as given information: information the speaker believes is already active in the listener's mind. 은/는 essentially says: "You know what we're talking about. Here's what's true about it."

2. 이/가: Introducing New Information

이/가 typically introduces something new into the conversation: information the listener doesn't yet have, or something being presented for the first time. This is why 이/가 dominates in storytelling and narrative:

The 이/가 on 일 (thing/event) introduces it as new. If you used 은/는 here, it would imply the listener already knew about this strange thing, which defeats the purpose of telling them.

3. 은/는: Contrast and Exclusion

This is the function most textbooks mention but rarely explain deeply. 은/는 carries an inherent contrastive meaning: it implies that the statement is true for the marked noun, but may not be true for others.

Linguist Susumu Kuno (1973), in his landmark analysis of Japanese (which maps almost perfectly onto Korean), called this the contrastive topic. The particle says: "As for X specifically, not necessarily Y or Z."

This contrastive meaning appears even when no second option is stated out loud:

The 는 on 커피 signals that coffee specifically is off the table, while leaving the door open for alternatives. Without it (커피를 안 마셔요), it's a flatter refusal with less nuance. This is also why 은/는 is so common with negation: negation is inherently contrastive.

4. 이/가: Exhaustive Identification (Focus)

This is the function most learners never hear about, and it explains many confusing cases where 이/가 seems to "emphasize" a noun even in sentences about known information.

Korean linguist Nam-Kil Kim (1985) described this as exhaustive identification: when 이/가 answers a question, it identifies the noun as the one and only correct answer. It's equivalent to spoken stress in English: "It was John who called" (not anyone else).

This is why answers to 누가 (who) questions almost always use 이/가. The subject marker here isn't just marking grammar: it's saying "this is the specific answer you asked for, and no one else."

The New Information → Topic Chain

One of the most useful patterns in extended speech is how 이/가 and 은/는 work together across sentences. Linguist Knud Lambrecht (1994) described this pattern as topic continuity, and Korean handles it more explicitly than almost any other language:

1. First mention: use 이/가 (new information)
2. Subsequent mentions: use 은/는 (now established as topic), or drop the noun entirely

This three-step pattern (introduce with 이/가, continue with 은/는, then drop) is the backbone of Korean narrative structure.

Special Environments

Embedded Clauses and Relative Clauses

Inside embedded clauses (after -고, -서, -면, -때, etc.) and relative clauses, 은/는 is generally not used. You'll almost always see 이/가:

The reason: 은/는 is a discourse-level marker: it signals something about the overall topic of the conversation. Embedded clauses are subordinate; they don't set discourse topics. 이/가, as the grammatical subject marker, works naturally in these environments.

Existential Sentences (있다 / 없다)

Questions with 뭐 / 누가 / 어디

When the question word itself is the focus, it takes 이/가:

But when the noun is the topic and something else is being questioned about it, 은/는 is used:

The One Mental Model That Ties It All Together

When in doubt, ask yourself two questions:

1. Is this information new to the conversation, or already established? → New: 이/가 / Established: 은/는
2. Am I implying a contrast, or identifying something specifically? → Contrast: 은/는 / Identification: 이/가

Why Native Speakers "Just Know"

Native speakers don't consciously apply these rules: they feel them. The contrast and focus meanings of 은/는 and 이/가 are baked into Korean's pragmatics from childhood. For learners, the fastest path to this intuition is massive input: reading Korean texts, watching Korean shows and, critically, getting corrected by a native speaker when your choice sounds off.

These rules won't make you perfect overnight. But they'll stop you from being randomly confused, and start making you specifically confused, which is a real improvement.

References

• Li, C. N., & Thompson, S. A. (1976). Subject and topic: A new typology of language. In C. N. Li (Ed.), Subject and Topic (pp. 457–489). Academic Press.
• Kuno, S. (1973). The Structure of the Japanese Language. MIT Press. [Chapter on は vs. が: directly parallel to Korean 은/는 vs 이/가]
• Chafe, W. (1976). Givenness, contrastiveness, definiteness, subjects, topics, and point of view. In C. N. Li (Ed.), Subject and Topic (pp. 25–55). Academic Press.
• Kim, N. K. (1985). The topic marker and the subject marker in Korean. Papers in Linguistics, 18(3).
• Lambrecht, K. (1994). Information Structure and Sentence Form: Topic, Focus, and the Mental Representations of Discourse Referents. Cambridge University Press.
• Sohn, H. M. (1999). The Korean Language. Cambridge University Press.
• Kuroda, S. Y. (1972). The categorical and the thetic judgment: Evidence from Japanese syntax. Foundations of Language, 9(2), 153–185.