Topic and Focus

In Japanese, knowing what is the topic and what is the focus helps understand how the topic-marker wa は particle and the subject-marker ga が particle work.

• Identification
• In Japanese
  
  • Focus to Topic
  • Discourse Topic
• Contrast
  
  • Contrastive Topic
  • Contrastive Focus
• References

Identification

In order to identify what the topic of a sentence is, it's easier to start by identifying the focus.

• Presupposition: what is already known.
• Assertion: what will be known after listening to the sentence.
• Focus: what will be known that wasn't known before.

The simplest way to understand these is with a series of questions. That's because whenever a questioner asks a question, it's because he doesn't know the thing he's asking for. Therefore, it can't be part of the presupposition, it must be part of the focus.

1. Who ate a banana?
   • I ate a banana.
2. You did what to a banana?
   • I ate a banana.
3. Did you eat two bananas?
   • I ate a banana.
4. What did you eat?
   • I ate a banana.
5. You ate a what?
   • I ate a banana.
6. What did you do?
   • I ate a banana.
7. Who did what to a banana?
   • I ate a banana.
8. What happened?!
   • I ATE A BANANA!!!
   • Dear Kamisama! How many times do I have to say it until you presuppose all of it?!

Above, the questioner always knows part of what happened, and always asks about what he doesn't know yet.

If he doesn't know "who did what," the subject is the focus. If he doesn't know to what was something done, the object is the focus. If he doesn't know who, did what, to whom, when, where, how, and why, then the entire sentence is the focus.

The focus is never part of the presupposition, while the topic is always part of the presupposition.

Although the topic and focus are never the same, they aren't exactly the opposite of each other. Instead, they're part of two distinct pairs of terms:

1. Topic-comment: the comment is what we say about the topic.
2. Focus-background: the focus is new information, the background is old.

The topic isn't the focus, so it's part of the background. Similarly, the focus isn't part of the topic, so it's part of the comment.

• Topic + comment (in which is the focus).
• Focus + background (in which is the topic).

Note that, when the entire sentence has focus, there's no background. The topic is part of the background, and if there's no background, there's nowhere for the topic to be, so there's no topic. Topic-less sentences exist.

In Japanese

The topic-marker wa は marks the topic. In other words, whatever it marks must be part of the presupposition, not part of the focus.

• banana wo tabeta no wa dare desu ka?
  バナナを食べたのは誰ですか？
  The one [who] ate the banana is whom?
  Who ate the banana?
• banana wo tabeta no wa watashi desu
  バナナを食べたのは私です
  The one [who] ate the banana is me.
  I ate the banana.

By this logic, if we don't have a wa は particle in a sentence, we don't have a topic, so nothing is part of the presupposition, and everything is part of the focus, so we have sentence-focus.

• nani ga atta?
  何があった？
  What existed?
  What happened?
• watashi ga banana wo tabeta
  私がバナナを食べた
  I ate a banana.

In this case, the ga が particle is said to express a "neutral description," as both parts of the sentence have equal (neutral) informational value.

However, the ga が particle has another function, called "exhaustive listing," in which it marks only the focus of the sentence, implying the rest of the sentence is the presupposition.

• dare ga banana wo tabeta?
  誰がバナナを食べた？
  Who ate a banana?
• watashi ga banana wo tabeta
  私がバナナを食べた
  I ate a banana.

This is the reason why you can only use ga が with interrogative pronouns like "who," "when," "where," and so on. They are all things you don't know about, so they aren't part of the presupposition, and therefore can't be the topic.

• *dare wa banana wo tabeta?
  誰はバナナを食べた
  (if I knew this I wouldn't be asking!)

Focus to Topic

The focus is an information you don't know about yet. That's not part of the discourse. However, once the speaker has brought it up, the listener will become aware of it.

That means the focus of one sentence can be the topic of a following sentence.

• What happened?!
• banaga ga dare-ka ni taberareta!
  バナナが誰かに食べられた！
  The banana was eaten by someone!
• Oh no!
• banana wa watashi ga tabetakatta noni...
  バナナは私が食べたかったのに･･･
  Even though, the banana, I wanted to eat...

Above, information regarding the banana, and what happened to it, were introduced in the first sentence.

In the second sentence, the banana was already part of the presupposition. We wanted to say something about it, so we marked it as the topic. What we said about it is the focus, since you didn't know yet that we "wanted to eat" the banana.

Discourse Topic

In Japanese, a topic introduced in a sentence doesn't need to be reintroduced in subsequent sentences.

• banana wa kieta
  バナナは消えた
  The banana disappeared.
• dare ga tabeta?
  誰が食べた？
  Who ate?
  • This means:
  • banana wa dare ga tabeta?
    バナナは誰が食べた？
    Who ate the banana?

Contrast

The term "contrast" refers to the juxtaposition of differing information. It can happen in two ways:

1. Contrastive Topic: in which a topic contrasts with another topic.
2. Contrastive Focus: in which a focus contrast with another focus.

Surely enough, in Japanese both happen.

Contrastive Topic

The contrastive topic happens when what's said about one topic contrasts with what was said about another topic. This easily happens when you have a "but," "however," and so on joining two clauses.:

• banana wa tabeta kedo
  ringo wa tabete-inai
  バナナは食べたけど
  リンゴは食べていない
  [I] ate the banana, however,
  [I] didn't eat the apple.

Above, what's said about the banana and the apple contrast with each other, so we have a contrastive topic.

The contrastive topic doesn't always show up in pairs. Sometimes you have just one word marked by wa は but it's interpreted with contrast nonetheless.

• neko wa suki
  猫は好き
  Cats are liked.
  [I] like cats.
  • Contrast: I don't like other animals.

This happens when you have two topics in a single sentence. The second wa は is interpreted with contrastive..

• watashi wa neko ga suki
  私は猫が好き
  As for me, cats are liked.
  I like cats.
  • (no contrast.)
• watashi wa neko wa suki
  私は猫は好き
  As for me, cats are liked.
  I, cats, like.
  • Contrast: I don't like other animals.

In Japanese, you usually don't mark yourself as the topic, as most statements can be assumed to be about you. In other words, it's already implied you're the topic of any opinions you utter.

This means watashi wa neko wa suki and just neko wa suki can be interpreted as the same thing.

Contrastive Focus

The contrastive focus happens when the information given by the focus contrasts with the one given by another focus. This easily happens when one person says one thing and another contradicts them.

• ame ga futteiru!
  雨が降っている！
  Rain is raining!
  [It's] raining!
• ame wa futteinai,
  yuki ga futteiru.
  雨は降っていない、
  雪が降っている
  Rain isn't raining, snow is raining.
  [It] isn't raining, [it] is snowing.

Above, we contradict the assertion that "rain is raining" by saying that "snow is raining" instead. Here, "what is raining?" is our focus.

References

• Vermeulen, R., 2011. The syntax of topic, contrast and contrastive topic. MIT Working Papers in Linguistics, 58.