Topics and は

To an English-speaking layman, the words “topic” and “subject” seem pretty much identical. They both can mean “what we’re currently discussing”.

Grammarians, though, make a distinction:

• The grammatical subject refers to the “doer” in a clause. The Japanese word for “subject” is 主語(しゅご). It’s the “master” that is doing whatever is indicated by the predicate. (The predicate specifies whether the “master” is performing an action or just “existing” in some state.)

• The word topic (題目(だいもく)) is reserved for “what we’re currently discussing”. It simply provides overall context. A topic might be explicit (actually mentioned within a sentence) or implicit (from prior sentences or based on where a conversation is occurring).

  A sentence might mean different things in different contexts. The topic clarifies what specific meaning was intended.

English doesn’t use explicit topics very often. When we do, it’s usually with a construct like:

As for ◯, …

or

Regarding ◯, …

The topic is whatever was in the circle.

Japanese, however, uses explicit topics (題目(だいもく)) all the time. This leads to much confusion for English-speaking language learners, since even extremely simple and incredibly common sentences contain explicit topics but only implicit subjects.

I am an American

Take this extremely simple, common sentence:

私(わたし)はアメリカ人(じん)です

Most people would translate that into English as “I am an American”.

Semantically, that would be absolutely correct. That’s what the sentence means.

Structurally, though, that’s not what the sentence actually says!

We use a more literal transliteration (vs. translation) in the diagram below:

私(わたし)はアメリカ人(じん)です

Me, [I] am-American-person

The character 私 in this sentence is the 題目 (topic) “me” and not the grammatical subject (that’s why it goes on a dotted line, and not on the “core” clause baseline). A topic is never the “doer” in a sentence, it just provides context. The subject does the doing or being, not the topic.

Think of it this way: the topic is “me”, but the implied logical subject is “I”. The literal, syntactic subject isn’t explicitly provided (so we imagine the zero pronoun standing in for it).

Notes:

• For such a simple sentence, there’s more going on here than you might think:

  • The topic is “me” (not “I”). Topics are indicated by the particle は. We diagram topics with dotted lines connecting to the clauses they affect (implying context, not action/state).

  • The subject (主語) is the zero pronoun, @, standing in for “I”.

  • The predicate (述語) is アメリカ人です.

    • アメリカ人 is a 名詞 (noun) meaning American-person. In English, “American” can also be a noun meaning the same thing, but we use “American-person” to make it explicit that it’s a noun and not the adjective “American”.

    • です is a 助動詞 (auxiliary verb) acting as a copula. It’s the polite form of だ.

      • 助動詞 never work on their own, they are auxiliary words that must always attach to other words.

      • A copula couples the preceding noun to the subject (just like the English words “is” or “am”). In this case, it says that the subject (@) is an American person.

    • The combination of 名詞＋助動詞 forms a 用言. It’s correct to think of アメリカ人です as one grammatical unit, an “is-verb”.

• The “core” clause of the sentence is just アメリカ人です (“is-American-person”). The topic is not part of the core clause.

• If we were to read the transliteration aloud, it would be: “me, am-American-Person”. As always, we skip over the stuff in brackets.

  There really is a logical subject in this sentence, even though it’s merely implied. If we changed it to「私は彼がアメリカ人です」 (“As for me, he is an American person”), it would sound weirdly verbose, but it is grammatically correct and has the identical semantic meaning.

Exposing all this hidden complexity for such a simple sentence probably seems unnecessary and possibly counter-productive, especially for such a simple sentence where the topic and logical subject refer to the same thing. But this is exactly how this sentence actually works.

Exposing this complexity in a diagram this way pays dividends once we start analyzing more complex sentences.

Topics and subjects can differ

In 私はアメリカ人です, the topic and the subject were the same human being (私). That won’t always be the case.

Take, for example, the English sentence “Every Sunday, my father makes sushi”. Here, the topic is “Sunday” but the subject of the primary clause is “my father”.

In Japanese:

毎週日曜日(まいしゅうにちようび)はお父(とう)さんが寿司(すし)を作(つく)る

Every-week-Sunday, father makes sushi

Notes:

• The topic is the long, compound word 毎週日曜日. This is a single compound 名詞 (noun) meaning “every Sunday” in English.

  The first two characters mean “every week”. The final three characters are themselves a 名詞 meaning “Sunday”. All together it expresses the semantic concept “every-week-Sunday” or “every Sunday”.

  When kanji are just jammed together like this, where each part sequentially qualifies the next without any particles in between, think of them as single compound nouns.

  If the sentence had started 毎週の日曜日は〜, we would have shown 毎週の as a modifier hanging below the topic of 日曜日. Since there is no intervening particle, we’ve diagrammed it as a compound-noun instead.

• The core clause is お父さんが作る (“father makes”). The subject is お父さん (father) and the predicate is 作る (make).

• There is an explicit object in this example, 寿司, introduced with the particle を, so we hang it below the predicate. “Father makes sushi”.