Transitivity

Japanese verbs are often categorized into one of two categories — "transitive" or "intransitive".

WHAT IS TRANSITIVITY?

A verb that is transitive involves the transfer of energy from one entity to another, namely from a subject to an object.

ジェニーがドアを開けた。Jenny opened the door.

This is a typical transitive sentence. The subject, Jenny, transfers energy to the door, causing it to open. It involves one entity acting upon another, which explains why the Japanese term for "transitive verb" is 他動詞たどうし — "other verb".

An intransitive verb is the opposite of a transitive one. There is no transfer of energy between a subject and object. Instead, the verb expresses a change in the subject.

ドアが開いた。The door opened.

In this intransitive sentence, we have no idea how or why the door opened, we just know that it happened… creepy 👻 Maybe a ghost opened it, or maybe it was the wind. In any case, the sentence presents "open" as though it happens independently, or by itself. This explains the native Japanese term for intransitive verbs — 自動詞じどうし, or "self verb".

TRANSITIVITY PAIRS

In Japanese, there are a large number of verbs that come in pairs, with each side of the pair having a transitive or intransitive meaning.

Japanese does something different — many verbs are part of a pair that share a root, but have different endings depending on their transitivity. In the examples above, you'll see that 開けるあ　　 is used in the transitive sentence, and 開くあ　 is used in the intransitive sentence. Not all Japanese verbs are part of a pair, but there are at least 300 pairs that exist in modern Japanese. Check out this great resource from Meguro Language Center for examples of pairs with visuals and context sentences.

PARTICLES を AND が

While there are some exceptions, transitive verbs will take an object marked with particle を, and intransitive verbs will only take a subject, marked with particle が.

キャメロンが電気をつけた。Cameron turned on the lights.

In this transitive sentence, 電気 (lights) is the object, and is marked with particle を. We also see a subject, Cameron, marked with particle が.

電気がつきました。The lights came on.

In this intransitive sentence, 電気 is not the object, it's the subject, and so it is marked with particle が.

These particles are a helpful hint when you're trying to determine if a verb is transitive or intransitive, but there are a variety of reasons why you can't rely on them as a rule of thumb. For one, it's common to drop both subjects and objects from sentences when they are known from context. Consider the following conversation for example:

コウイチ:先生、トイレ行っていい？

まみ先生:(授業が) 始まる前に行きなさい。

〜Koichi goes to the bathroom and comes back🚽〜

まみ先生:コウイチくん、お帰り。では、(私が) (授業を) 始めます。

As you can see, both verbs in the transitivity pair 始まるはじ(something begins) and 始めるはじ(to start something) appear in this dialogue, but particle を and が are nowhere to be found!